Packages and Binaries:
swaks
swaks (Swiss Army Knife SMTP) is a command-line tool written in Perl for testing SMTP setups; it supports STARTTLS and SMTP AUTH (PLAIN, LOGIN, CRAM-MD5, SPA, and DIGEST-MD5). swaks allows one to stop the SMTP dialog at any stage, e.g to check RCPT TO: without actually sending a mail.
If you are spending too much time iterating “telnet foo.example 25” swaks is for you.
Installed size: 313 KB
How to install: sudo apt install swaks
Dependencies:
- perl
swaks
Swiss Army Knife SMTP, the all-purpose SMTP transaction tester
root@kali:~# swaks --help
SWAKS(1) SWAKS SWAKS(1)
NAME
Swaks - Swiss Army Knife SMTP, the all-purpose SMTP transaction tester
DESCRIPTION
Swaks' primary design goal is to be a flexible, scriptable, transaction-
oriented SMTP test tool. It handles SMTP features and extensions such
as TLS, authentication, and pipelining; multiple version of the SMTP
protocol including SMTP, ESMTP, and LMTP; and multiple transport methods
including UNIX-domain sockets, internet-domain sockets, and pipes to
spawned processes. Options can be specified in environment variables,
configuration files, and the command line allowing maximum
configurability and ease of use for operators and scripters.
QUICK START
Deliver a standard test email to [email protected] on port 25 of
test-server.example.net:
swaks --to [email protected] --server test-server.example.net
Deliver a standard test email, requiring CRAM-MD5 authentication as user
[email protected]. An "X-Test" header will be added to the email body.
The authentication password will be prompted for if it cannot be
obtained from your .netrc file.
swaks --to [email protected] --from [email protected] --auth CRAM-MD5 --auth-user [email protected] --header-X-Test "test email"
Test a virus scanner using EICAR in an attachment. Don't show the
message DATA part.:
swaks -t [email protected] --attach - --server test-server.example.com --suppress-data </path/to/eicar.txt
Test a spam scanner using GTUBE in the body of an email, routed via the
MX records for example.com:
swaks --to [email protected] --body @/path/to/gtube/file
Deliver a standard test email to [email protected] using the LMTP
protocol via a UNIX domain socket file
swaks --to [email protected] --socket /var/lda.sock --protocol LMTP
Report all the recipients in a text file that are non-verifiable on a
test server:
for E in `cat /path/to/email/file`
do
swaks --to $E --server test-server.example.com --quit-after RCPT --hide-all
[ $? -ne 0 ] && echo $E
done
TERMS AND CONVENTIONS
This document tries to be consistent and specific in its use of the
following terms to reduce confusion.
Target
The target of a transaction is the thing that Swaks connects to.
This generic term is used throughout the documentation because most
other terms improperly imply something about the transport being
used.
Transport
The transport is the underlying method used to connect to the
target.
Transaction
A transaction is the opening of a connection over a transport to a
target and using a messaging protocol to attempt to deliver a
message.
Protocol
The protocol is the application language used to communicate with
the target. This document uses SMTP to speak generically of all
three supported protocols unless it states that it is speaking of
the specific 'SMTP' protocol and excluding the others.
Message
SMTP protocols exist to transfer messages, a set of bytes in an
agreed-upon format that has a sender and a recipient.
Envelope
A message's envelope contains the "true" sender and receiver of a
message. It can also be referred to as its components, envelope-
sender and envelope-recipients. It is important to note that a
messages envelope does not have to match its "To:" and "From:"
headers.
DATA
The DATA portion of an SMTP transaction is the actual message that
is being transported. It consists of both the message's headers and
its body. DATA and body are sometimes used synonymously, but they
are always two distinct things in this document.
Headers
A message's headers are defined as all the lines in the message's
DATA section before the first blank line. They contain information
about the email that will be displayed to the recipient such as
"To:", "From:", "Subject:", etc. In this document headers will
always be written with a capitalized first letter and a trailing
colon.
Body
A message's body is the portion of its DATA section following the
first blank line.
Option
An option is a flag which changes Swaks' behavior. Always called an
option regardless of how it is provided. For instance,
"--no-data-fixup" is an option.
Argument
When an option takes addition data beside the option itself, that
additional data is called an argument. In "--quit-after
<stop-point>'", "<stop-point>" is the argument to the "--quit-after"
option.
<literal-string>
When used in the definition of an option, text that is inside of
angle brackets ("<>") indicates a descriptive label for a value that
the user should provide. For instance, "--quit-after <stop-point>"
indicates that "<stop-point>" should be replaced with a valid stop-
point value.
[<optional-value>]
When used in the definition of an option, text inside of square
brackets ([]) indicates that the value is optional and can be
omitted. For instance, "--to [<recipient>]" indicates that the
"--to" option can be used with or without a specified "<recipient>".
OPTION PROCESSING
To prevent potential confusion in this document a flag to Swaks is
always referred to as an "option". If the option takes additional data,
that additional data is referred to as an argument to the option. For
example, "--from [email protected]" might be provided to Swaks on the
command line, with "--from" being the option and "[email protected]"
being "--from"'s argument.
Options and arguments are the only way to provide information to Swaks.
If Swaks finds data during option processing that is neither an option
nor an option's argument, it will error and exit. For instance, if
"--no-data-fixup 1" were found on the command line, this would result in
an error because "--no-data-fixup" does not take an argument and
therefore Swaks would not know what to do with 1.
Options can be given to Swaks in three ways. They can be specified in a
configuration file, in environment variables, and on the command line.
Depending on the specific option and whether an argument is given to it,
Swaks may prompt the user for the argument.
When Swaks evaluates its options, it first looks for a configuration
file (either in a default location or specified with "--config"). Then
it evaluates any options in environment variables. Finally, it
evaluates command line options. At each round of processing, any
options set earlier will be overridden. Additionally, any option can be
prefixed with "no-" to cause Swaks to forget that the variable had
previously been set (either in an earlier round, or earlier in the same
round). This capability is necessary because many options treat
defined-but-no-argument differently than not-defined.
As a general rule, if the same option is given multiple time, the last
time it is given is the one that will be used. This applies to both
intra-method (if "--from [email protected] --from [email protected]" is
given, "[email protected]" will be used) and inter-method (if "from
[email protected]" is given in a config file and "--from
[email protected]" is given on the command line, "[email protected]"
will be used)
Each option definition ends with a parenthetical synopsis of how the
option behaves. The following codes can be used
Arg-None, Arg-Optional, Arg-Required
These three codes are mutually exclusive and describe whether or not
the option takes an argument. Note that this does not necessarily
describe whether the argument is required to be specified directly,
but rather whether an argument is required eventually. For
instance, "--to" is labeled as Arg-Required, but it is legal to
specify "--to" on the command line without an argument. This is
because Swaks can prompt for the required argument if it is not
directly provided.
From-Prompt
An option labeled with From-Prompt will prompt the user
interactively for the argument if none is provided.
From-File
An option labeled with From-File will handle arguments as files in
certain situations.
If the initial argument is "-", the final argument is the contents
of "STDIN". Multiple options can all specify "STDIN", but the same
content will be used for each of them.
If the initial argument is prefixed with "@", the argument will be
treated as a path to a file. The file will be opened and the
contents will be used as the final argument. If the contents of the
file can't be read, Swaks will exit. To specify a literal string
value starting with an "@", use two "@" symbols. The first will be
stripped. It is not possible to include an unqualified file which
starts with an "@" sign (like "--attach @file.txt" or "--attach
@@file.txt"), but if you include a path to the file which splits up
the two "@" signs, that will work (eg "--attach @./@file.txt" will
include the contents of the file @file.txt).
Sensitive
If an option marked Sensitive attempts to prompt the user for an
argument and the "--protect-prompt" option is set, Swaks will
attempt to mask the user input from being echoed on the terminal.
Swaks tries to mask the input in several ways, but if none of them
work program flow will continue with unmasked input.
Deprecated
An option labeled Deprecated has been officially deprecated and will
be removed in a future release. See the "DEPRECATIONS" section of
this documentation for details about the deprecations.
The exact mechanism and format for using each of the types is listed
below.
CONFIGURATION FILES
A configuration file can be used to set commonly-used or abnormally
verbose options. By default, Swaks looks in order for
$SWAKS_HOME/.swaksrc, $HOME/.swaksrc, and $LOGDIR/.swaksrc. If one
of those is found to exist (and "--config" has not been used) that
file is used as the configuration file.
Additionally, a configuration file in a non-default location can be
specified using "--config". If this is set and not given an
argument Swaks will not use any configuration file, including any
default file. If "--config" points to a readable file, it is used
as the configuration file, overriding any default that may exist.
If it points to a non-readable file an error will be shown and Swaks
will exit.
A set of "portable" defaults can also be created by adding options
to the end of the Swaks program file. As distributed, the last line
of Swaks should be "__END__". Any lines added after "__END__" will
be treated as the contents of a configuration file. This allows a
set of user preferences to be automatically copied from server to
server in a single file.
If configuration files have not been explicitly turned off, the
"__END__" config is always read. Only one other configuration file
will ever be used per single invocation of Swaks, even if multiple
configuration files are specified. If the "__END__" config and
another config are to be read, the "__END__" config will be
processed first. Specifying the "--config" option with no argument
turns off the processing of both the "__END__" config and any actual
config files.
In a configuration file lines beginning with a hash ("#") are
ignored. All other lines are assumed to be an option to Swaks, with
the leading dash or dashes optional. Everything after an option
line's first space is assumed to be the option's argument and is not
shell processed. Therefore, quoting is usually unneeded and will be
included literally in the argument.
There is a subtle difference between providing an option with no
argument and providing an option with an empty argument. If an
option line does not have a space, the entire line is treated as an
option and there is no argument. If the line ends in a single
space, it will be processed as an option with an empty argument.
So, "apt" will be treated as "--apt", but "apt " will be treated as
"--apt ''".
Here is an example of the contents of a configuration file:
# always use this sender, no matter server or logged in user
--from [email protected]
# I prefer my test emails have a pretty from header. Note
# the lack of dashes on option and lack of quotes around
# entire argument.
h-From: "Fred Example" <[email protected]>
Options specific to configuration file:
--config [<config-file>]
This option provides a path to a specific configuration file to
be used. If specified with no argument, no automatically-found
configuration file (via $HOME, etc, or "__END__") will be
processed. If the argument is a valid file, that file will be
used as the configuration file (after "__END__" config). If
argument is not a valid, readable file, Swaks will error and
exit. This option can be specified multiple times, but only the
first time it is specified (in environment variable and the
command line search order) will be used. (Arg-Optional)
CONFIGURATION ENVIRONMENT VARIABLES
Options can be supplied via environment variables. The variables
are in the form $SWAKS_OPT_name, where "name" is the name of the
option that would be specified on the command line. Because dashes
aren't allowed in environment variable names in most UNIX-ish
shells, no leading dashes should be used and any dashes inside the
option's name should be replaced with underscores. The following
would create the same options shown in the configuration file
example:
$ SWAKS_OPT_from='[email protected]'
$ SWAKS_OPT_h_From='"Fred Example" <[email protected]>'
Setting a variable to an empty value is the same as specifying it on
the command line with no argument. For instance, setting
<SWAKS_OPT_server=""> would cause Swaks to prompt the user for the
server to which to connect at each invocation. On Windows, it is
not possible to set empty environment variables. The behavior can
be simulated by setting the environment variable to "<>" instead.
Additionally, embedding the header name in the header option via
environment variable is not allowed on Windows (eg
"SWAKS_OPT_header_Foo=bar" will result in an error, but
"SWAKS_OPT_header="Foo: bar"" will work.)
Because there is no inherent order in options provided by setting
environment variables, the options are sorted before being
processed. This is not a great solution, but it at least defines
the behavior, which would be otherwise undefined. As an example, if
both $SWAKS_OPT_from and $SWAKS_OPT_f were set, the value from
$SWAKS_OPT_from would be used, because it sorts after $SWAKS_OPT_f.
Also as a result of not having an inherent order in environment
processing, unsetting options with the "no-" prefix is unreliable.
It works if the option being turned off sorts before "no-", but
fails if it sorts after. Because "no-" is primarily meant to operate
between config types (for instance, unsetting from the command line
an option that was set in a config file), this is not likely to be a
problem.
In addition to setting the equivalent of command line options,
$SWAKS_HOME can be set to a directory containing the default
.swaksrc to be used.
COMMAND LINE OPTIONS
The final method of supplying options to Swaks is via the command
line. The options behave in a manner consistent with most UNIX-ish
command line programs. Many options have both a short and long form
(for instance "-s" and "--server"). By convention short options are
specified with a single dash and long options are specified with a
double-dash. This is only a convention and either prefix will work
with either type.
The following demonstrates the example shown in the configuration
file and environment variable sections:
$ swaks --from [email protected] --h-From: '"Fred Example" <[email protected]>'
TRANSPORTS
Swaks can connect to a target via UNIX pipes ("pipes"), UNIX domain
sockets ("UNIX sockets"), or internet domain sockets ("network
sockets"). Connecting via network sockets is the default behavior.
Because of the singular nature of the transport used, each set of
options in the following section is mutually exclusive. Specifying more
than one of "--server", "--pipe", or "--socket" will result in an error.
Mixing other options between transport types will only result in the
irrelevant options being ignored. Below is a brief description of each
type of transport and the options that are specific to that transport
type.
NETWORK SOCKETS
This transport attempts to deliver a message via TCP/IP, the
standard method for delivering SMTP. This is the default transport
for Swaks. If none of "--server", "--pipe", or "--socket" are given
then this transport is used and the target server is determined from
the recipient's domain (see "--server" below for more details).
This transport requires the IO::Socket::IP module for both IPv4 and
IPv6 sockets. If this module is not loadable, Swaks will attempt to
use the IO::Socket library for IPv4 and IO::Socket::INET6 for IPv6
support. Attempting to use this transport with none of those
libraries available will result in an error and program termination.
The fall back to IO::Socket and IO::Socket::INET6 is deprecated and
will be removed in a future release. See DEPRECATIONS below
-s, --server [<target-server>[:<port>]]
Explicitly tell Swaks to use network sockets and specify the
hostname or IP address to which to connect, or prompt if no
argument is given. If this option is not given and no other
transport option is given, the target mail server is determined
from the appropriate DNS records for the domain of the recipient
email address using the Net::DNS module. If Net::DNS is not
available Swaks will attempt to connect to localhost to deliver.
The target port can optionally be set here. Supported formats
for this include SERVER:PORT (supporting names and IPv4
addresses); [SERVER]:PORT and SERVER/PORT (supporting names,
IPv4 and IPv6 addresses). A port set via this option will only
be used if the "--port" option is not used. See also
"--copy-routing". (Arg-Required, From-Prompt)
-p, --port [<port>]
Specify which TCP port on the target is to be used, or prompt if
no argument is listed. The argument can be a service name (as
retrieved by getservbyname(3)) or a port number. The default
port is smtp/25 unless influenced by the "--protocol" or
"--tls-on-connect" options. (Arg-Required, From-Prompt)
-li, --local-interface [<local-interface>[:<port>]]
Use argument as the local interface for the outgoing SMTP
connection, or prompt user if no argument given. Argument can
be an IP address or a hostname. Default action is to let the
operating system choose the local interface. See "--server" for
additional comments on :<port> format. A port set via this
option will only be used if the "--port" option is not used.
(Arg-Required, From-Prompt)
-lp, --local-port, --lport [<port>]
Specify the outgoing port from which to originate the
transaction. The argument can be a service name (as retrieved
by getservbyname(3)) or a port number. If this option is not
specified the system will pick an ephemeral port. Note that
regular users cannot specify some ports. (Arg-Required, From-
Prompt)
--copy-routing <domain>
The argument is interpreted as the domain part of an email
address and it is used to find the target server using the same
logic that would be used to look up the target server for a
recipient email address. See "--to" option for more details on
how the target is determined from the email domain. (Arg-
Required)
-4, -6
Force IPv4 or IPv6. (Arg-None)
UNIX SOCKETS
This transport method attempts to deliver messages via a UNIX-domain
socket file. This is useful for testing MTA/MDAs that listen on
socket files (for instance, testing LMTP delivery to Cyrus). This
transport requires the IO::Socket::UNIX module which is part of the
standard Perl distribution. If this module is not loadable,
attempting to use this transport will result in an error and program
termination.
--socket [<socket-file>]
This option takes as its argument a UNIX-domain socket file. If
Swaks is unable to open this socket it will display an error and
exit. (Arg-Required, From-Prompt)
PIPES
This transport attempts to spawn a process and communicate with it
via pipes. The spawned program must be prepared to behave as a mail
server over "STDIN"/"STDOUT". Any MTA designed to operate from
inet/xinet should support this. In addition, some MTAs provide
testing modes that can be communicated with via "STDIN"/"STDOUT".
This transport can be used to automate that testing. For example,
if you implemented DNSBL checking with Exim and you wanted to make
sure it was working, you could run "swaks --pipe "exim -bh
127.0.0.2"". Ideally, the process you are talking to should behave
exactly like an SMTP server on "STDIN" and "STDOUT". Any debugging
should be sent to "STDERR", which will be directed to your terminal.
In practice, Swaks can generally handle some debug on the child's
"STDOUT", but there are no guarantees on how much it can handle.
This transport requires the IPC::Open2 module which is part of the
standard Perl distribution. If this module is not loadable,
attempting to use this transport will result in an error and program
termination.
--pipe [<command-and-arguments>]
Provide a process name and arguments to the process. Swaks will
attempt to spawn the process and communicate with it via pipes.
If the argument is not an executable Swaks will display an error
and exit. (Arg-Required, From-Prompt)
PROTOCOL OPTIONS
These options are related to the protocol layer.
-t, --to [<email-address>[,<email-address>[,...]]]
--cc [<email-address>[,<email-address>[,...]]]
--bcc [<email-address>[,<email-address>[,...]]]
These options all tell Swaks to use the argument(s) as the envelope-
recipient for the email. There are subtle differences between these
three options, detailed below. If any option is specified but with
no arguments, Swaks will prompt the user for an argument.
"--to" is special in that it is the only option required by Swaks.
There is no default value for this option. If no recipients are
provided via any means, user will be prompted to provide one
interactively. The only exception to this is if a "--quit-after"
value is provided which will cause the SMTP transaction to be
terminated before the recipient is needed. If multiple recipients
are provided and the recipient domain is needed to determine
routing, the domain of the last recipient in the "--to" argument
list is used.
The primary distinction between these options is how their arguments
are treated when generating the DATA portion of the email. They
each have their own replacement tokens ("%TO_ADDRESS%",
"%CC_ADDRESS%", and "%BCC_ADDRESS%" respectively) which can be used
by anyone crafting a custom DATA. In Swaks' default message,
"%TO_ADDRESS%" will be used for the To: header and, if it is
populated, "%CC_HEADER%" will be used for a Cc: header.
"%BCC_ADDRESS%" is not used in the default DATA. (Arg-Required,
From-Prompt)
-f, --from [<email-address>]
Use argument as envelope-sender for email, or prompt user if no
argument specified. The string "<>" can be supplied to mean the
null sender. If user does not specify a sender address a default
value is used. The domain-part of the default sender is a best
guess at the fully-qualified domain name of the local host. The
method of determining the local-part varies. If the $LOGNAME
environment variable is set, it will be used as the local-part.
Otherwise the value from "Win32::LoginName()" will be used on
Windows and getpwuid(3) on UNIX-ish platforms. See also
"--force-getpwuid". If Swaks cannot determine a local hostname and
the sender address is needed for the transaction, Swaks will error
and exit. In this case, a valid string must be provided via this
option. (Arg-Required, From-Prompt)
--ehlo, --lhlo, -h, --helo [<helo-string>]
String to use as argument to HELO/EHLO/LHLO command, or prompt user
if no argument is specified. If this option is not used a best
guess at the fully-qualified domain name of the local host is used.
If Swaks cannot determine a local hostname and the helo string is
needed for the transaction, Swaks will error and exit. In this
case, a valid string must be provided via this option. (Arg-
Required, From-Prompt)
-q, --quit, --quit-after <stop-point>
Point at which the transaction should be stopped. When the
requested stopping point is reached in the transaction, and provided
that Swaks has not errored out prior to reaching it, Swaks will send
"QUIT" and attempt to close the connection cleanly. These are the
valid arguments and notes about their meaning. (Arg-Required)
PROXY
Quit after the server sends a response to a PROXY request. Note
that if there is not an error negotiating proxy, this will be
synonymous with CONNECT.
CONNECT, BANNER
Terminate the session after receiving the greeting banner from
the target.
FIRST-HELO, FIRST-EHLO, FIRST-LHLO
In a STARTTLS (but not tls-on-connect) session, terminate the
transaction after the first of two HELOs. In a non-STARTTLS
transaction, behaves the same as HELO (see below).
XCLIENT
Quit after XCLIENT is negotiation. This always quits after the
point where XCLIENT would have been negotiated, regardless of
whether it was attempted.
XCLIENT-HELO
Quit after the HELO that XCLIENT negotiation triggers. This
differs from HELO and FIRST-HELO because XCLIENT negotiation can
happen at multiple points in the SMTP transaction and it is
impossible to specifically refer to the XCLIENT-triggered HELO
using the HELO or FIRST-HELO stop-points. This always quits
after the point where the XCLIENT-triggered HELO would have
occurred, regardless of whether it was attempted.
STARTTLS, TLS
Quit the transaction immediately following TLS negotiation.
Note that this happens in different places depending on whether
STARTTLS or tls-on-connect are used. This always quits after
the point where TLS would have been negotiated, regardless of
whether it was attempted.
HELO, EHLO, LHLO
In a STARTTLS or XCLIENT session, quit after the second HELO.
Otherwise quit after the first and only HELO.
AUTH
Quit after authentication. This always quits after the point
where authentication would have been negotiated, regardless of
whether it was attempted.
MAIL, FROM
Quit after MAIL FROM: is sent.
RCPT, TO
Quit after RCPT TO: is sent.
--da, --drop-after <stop-point>
The option is similar to "--quit-after", but instead of trying to
cleanly shut down the session it simply terminates the session.
This option accepts the same stop-points as "--quit-after" and
additionally accepts DATA and DOT, detailed below. (Arg-Required)
DATA
Drop the connection after DATA is sent by server.
DOT Drop the connection after the final '.' of the message is sent
by server.
--das, --drop-after-send <stop-point>
This option is similar to "--drop-after", but instead of dropping
the connection after reading a response to the stop-point, it drops
the connection immediately after sending stop-point. It accepts the
same stop-points as "--drop-after". If the stop-point is for an
optional part of the transaction which is not actually sent (for
instance STARTTLS or AUTH), this option will behave identically to
"--drop-after". See below for specific details. (Arg-Required)
CONNECT
Connect to the server and then drops the connection before
receiving the server's banner.
STARTTLS, TLS
Behaves identically to "--drop-after".
HELO, EHLO, LHLO
Doesn't necessarily work as expected. If it appears to read the
HELO response incorrectly, use FIRST-HELO instead.
--timeout [<time>]
Use argument as the SMTP transaction timeout, or prompt user if no
argument given. Argument can either be a pure digit, which will be
interpreted as seconds, or can have a specifier s, m, or h (5s = 5
seconds, 3m = 180 seconds, 1h = 3600 seconds). As a special case, 0
means don't timeout the transactions. Default value is 30s. (Arg-
Required, From-Prompt)
--protocol <protocol>
Specify which protocol to use in the transaction. Valid options are
shown in the table below. Currently the 'core' protocols are SMTP,
ESMTP, and LMTP. By using variations of these protocol types one
can tersely specify default ports, whether authentication should be
attempted, and the type of TLS connection that should be attempted.
The default protocol is ESMTP. The following table demonstrates the
available arguments to "--protocol" and the options each sets as a
side effect. (Arg-Required)
SMTP
HELO, "-p 25"
SSMTP
EHLO->HELO, "-tlsc -p 465"
SSMTPA
EHLO->HELO, "-a -tlsc -p 465"
SMTPS
HELO, "-tlsc -p 465"
ESMTP
EHLO->HELO, "-p 25"
ESMTPA
EHLO->HELO, "-a -p 25"
ESMTPS
EHLO->HELO, "-tls -p 25"
ESMTPSA
EHLO->HELO, "-a -tls -p 25"
LMTP
LHLO, "-p 24"
LMTPA
LHLO, "-a -p 24"
LMTPS
LHLO, "-tls -p 24"
LMTPSA
LHLO, "-a -tls -p 24"
--pipeline
If the remote server supports it, attempt SMTP PIPELINING (RFC
2920). (Arg-None)
--prdr
If the server supports it, attempt Per-Recipient Data Response
(PRDR) (<https://tools.ietf.org/html/draft-hall-prdr-00.txt>). PRDR
is not yet standardized, but MTAs have begun implementing the
proposal. (Arg-None)
--force-getpwuid
Tell Swaks to use the system-default method of determining the
current user's username for the default sender local-part instead of
trying $LOGNAME first. Despite the UNIX-ish-specific option name,
this option also works on Windows. (Arg-None)
TLS / ENCRYPTION
These are options related to encrypting the transaction. These have
been tested and confirmed to work with all three transport methods. The
Net::SSLeay module is used to perform encryption when it is requested.
If this module is not loadable Swaks will either ignore the TLS request
or error out, depending on whether the request was optional. STARTTLS
is defined as an extension in the ESMTP protocol and will be unavailable
if "--protocol" is set to a variation of plain SMTP. Because it is not
defined in the protocol itself, "--tls-on-connect" is available for any
protocol type if the target supports it.
A local certificate is not required for a TLS connection to be
negotiated. However, some servers use client certificate checking to
verify that the client is allowed to connect. Swaks can be told to use
a specific local certificate using the "--tls-cert" and "--tls-key"
options, and optionally to use a certificate chain using the
"--tls-chain" option.
-tls
Require connection to use STARTTLS. Exit if TLS not available for
any reason (not advertised, negotiations failed, etc). (Arg-None)
-tlso, --tls-optional
Attempt to use STARTTLS if available, continue with normal
transaction if TLS was unable to be negotiated for any reason. Note
that this is a semi-useless option as currently implemented because
after a negotiation failure the state of the connection is unknown.
In some cases, like a version mismatch, the connection should be
left as plaintext. In others, like a verification failure, the
server-side may think that it should continue speaking TLS while the
client thinks it is plaintext. There may be an attempt to add more
granular state detection in the future, but for now just be aware
that odd things may happen with this option if the TLS negotiation
is attempted and fails. (Arg-None)
-tlsos, --tls-optional-strict
Attempt to use STARTTLS if available. Proceed with transaction if
TLS is negotiated successfully or STARTTLS not advertised. If
STARTTLS is advertised but TLS negotiations fail, treat as an error
and abort transaction. Due to the caveat noted above, this is a
much saner option than "--tls-optional". (Arg-None)
-tlsc, --tls-on-connect
Initiate a TLS connection immediately on connection. Following
common convention, if this option is specified the default port
changes from 25 to 465, though this can still be overridden with the
--port option. (Arg-None)
-tlsp, --tls-protocol <tls-version-specification>
Specify which protocols to use (or not use) when negotiating TLS.
At the time of this writing, the available protocols are sslv2,
sslv3, tlsv1, tlsv1_1, tlsv1_2, and tlsv1_3. The availability of
these protocols is dependent on your underlying OpenSSL library, so
not all of these may be available. The list of available protocols
is shown in the output of "--dump" (assuming TLS is available at
all).
The specification string is a comma-delimited list of protocols that
can be used or not used. For instance 'tlsv1,tlsv1_1' will only
succeed if one of those two protocols is available on both the
client and the server. Conversely, 'no_sslv2,no_sslv3' will attempt
to negotiate any protocol except sslv2 and sslv3. The two forms of
specification cannot be mixed. (Arg-Required)
--tls-cipher <cipher-string>
The argument to this option is passed to the underlying OpenSSL
library to set the list of acceptable ciphers to the be used for the
connection. The format of this string is opaque to Swaks and is
defined in
<https://www.openssl.org/docs/manmaster/man1/openssl-ciphers.html#CIPHER-LIST-FORMAT>.
A brief example would be "--tls-cipher '3DES:+RSA'". (Arg-Required)
--tls-verify
Tell Swaks to attempt to verify the server's certificate. This
option is identical to specifying both the "--tls-verify-ca" and
"--tls-verify-host" options. See those options for detailed
descriptions of how to fine-tune each type of verification.
By default, TLS verification is not required. If TLS verification
is required by "--tls-verify", "--tls-verify-ca", or
"--tls-verify-host" and the requested type of verification fails,
TLS negotiation will not succeed. (Arg-None)
--tls-verify-ca
Require that the server's certificate be signed by a known
certificate authority and not be expired. By default the list of
known CAs will be whatever is available via the client Swaks is
running on. To provide a custom CA, see "--tls-ca-path". (Arg-None)
--tls-verify-host
Require that the target of the current connection be listed in the
server certificate's Subject Alternative Name (SAN) or Subject
CommonName (CN).
The target that Swaks uses for verification will vary. It can be a
hostname, either provided directly via the "--server" option or
looked up via MX records. In this case, verification performs as
expected. If the target is an IP, the IP will be looked up in the
certificate, which is possible but unusual. If the transport is
"--pipe" or "--socket", there will not be a meaningful target to
verify in the certificate and verification will fail. In this
situation it's better to use only "--tls-verify-ca" or to override
the target used for verification with the "--tls-verify-target"
option. (Arg-None)
--tls-verify-target <verification-string>
When set, the argument to this option will be used as the host to be
verified for "--tls-verify-host". This is necessary when using
"--tls-verify-host" with either the "--pipe" or "--socket"
transports, which do not have a verifiable target by default. It
can also be used to override the default target lookup when using
the "--server" transport. For instance, it can be used to verify
that the certificate of a server explicitly connect to via IP
contains a specific certificate. (Arg-Required)
--tls-ca-path <ca-location>
Specify an alternate location for CA information for verifying
server certificates. The argument can point to a file or directory.
The default behavior is to use the underlying OpenSSL library's
default information. (Arg-Required)
--tls-cert <cert-file>
Provide a path to a file containing the local certificate Swaks
should use if TLS is negotiated. If a certificate chain needs to be
provided, it can be provided via this file or via a separate file
with "--tls-chain". The file path argument is required. As
currently implemented the certificate in the file must be in PEM
format. Contact the author if there's a compelling need for ASN1.
If this option is set, "--tls-key" is also required. (Arg-Required)
--tls-key <key-file>
Provide a path to a file containing the local private key Swaks
should use if TLS is negotiated. The file path argument is
required. As currently implemented the certificate in the file must
be in PEM format. Contact the author if there's a compelling need
for ASN1. If this option is set, "--tls-cert" is also required.
(Arg-Required)
--tls-chain <chain-file>
Provide a path to a file containing the local certificate chain
Swaks should use if TLS is negotiated. The file path argument is
required. As currently implemented the certificate in the file must
be in PEM format. Contact the author if there's a compelling need
for ASN1. If this option is set, "--tls-cert" and "--tls-key" are
also required. (Arg-Required)
--tls-get-peer-cert [<output-file>]
Get a copy of the TLS peer's certificate. If no argument is given,
it will be displayed to "STDOUT". If an argument is given it is
assumed to be a filesystem path specifying where the certificate
should be written. The saved certificate can then be examined using
standard tools such as the openssl command. If a file is specified
its contents will be overwritten. This option will only ever return
one certificate. In order to get every certificate sent by the
server, see "--tls-get-peer-chain". (Arg-Optional)
--tls-get-peer-chain [<output-file>]
Get a copy of the TLS certificate chain sent by the server. If no
argument is given, it will be displayed to "STDOUT". If an argument
is given it is assumed to be a filesystem path specifying where the
certificate should be written. The saved chain can then be examined
using standard tools such as the openssl command. If a file is
specified its contents will be overwritten. See also
"--tls-get-peer-cert". (Arg-Optional)
--tls-sni <sni-string>
Specify the Server Name Indication field to send when the TLS
connection is initiated. (Arg-Required)
AUTHENTICATION
Swaks will attempt to authenticate to the target mail server if
instructed to do so. This section details available authentication
types, requirements, options and their interactions, and other fine
points in authentication usage. Because authentication is defined as an
extension in the ESMTP protocol it will be unavailable if "--protocol"
is set to a variation of SMTP.
All authentication methods require base64 encoding. If the MIME::Base64
Perl module is loadable Swaks attempts to use it to perform these
encodings. If MIME::Base64 is not available Swaks will use its own
onboard base64 routines. These are slower than the MIME::Base64
routines and less reviewed, though they have been tested thoroughly.
Using the MIME::Base64 module is encouraged.
If authentication is required (see options below for when it is and
isn't required) and the requirements aren't met for the authentication
type available, Swaks displays an error and exits. Two ways this can
happen include forcing Swaks to use a specific authentication type that
Swaks can't use due to missing requirements, or allowing Swaks to use
any authentication type, but the server only advertises types Swaks
can't support. In the former case Swaks errors out at option processing
time since it knows up front it won't be able to authenticate. In the
latter case Swaks will error out at the authentication stage of the SMTP
transaction since Swaks will not be aware that it will not be able to
authenticate until that point.
Following are the supported authentication types including any
individual notes and requirements.
The following options affect Swaks' use of authentication. These
options are all inter-related. For instance, specifying "--auth-user"
implies "--auth" and "--auth-password". Specifying "--auth-optional"
implies "--auth-user" and "--auth-password", etc.
-a, --auth [<auth-type>[,<auth-type>[,...]]]
Require Swaks to authenticate. If no argument is given, any
supported auth-types advertised by the server are tried until one
succeeds or all fail. If one or more auth-types are specified as an
argument, each that the server also supports is tried in order until
one succeeds or all fail. This option requires Swaks to
authenticate, so if no common auth-types are found or no credentials
succeed, Swaks displays an error and exits. (Arg-Optional)
The following tables lists the valid auth-types
LOGIN, PLAIN
These basic authentication types are fully supported and tested
and have no additional requirements
CRAM-MD5
The CRAM-MD5 authenticator requires the Digest::MD5 module. It
is fully tested and believed to work against any server that
implements it.
DIGEST-MD5
The DIGEST-MD5 authenticator (RFC2831) requires the Authen::SASL
module. Version 20100211.0 and earlier used Authen::DigestMD5
which had some protocol level errors which prevented it from
working with some servers. Authen::SASL's DIGEST-MD5 handling
is much more robust.
The DIGEST-MD5 implementation in Swaks is fairly immature. It
currently supports only the "auth" qop type, for instance. If
you have DIGEST-MD5 experience and would like to help Swaks
support DIGEST-MD5 better, please get in touch with me.
The DIGEST-MD5 protocol's "realm" value can be set using the
"--auth-extra" "realm" keyword. If no realm is given, a
reasonable default will be used.
The DIGEST-MD5 protocol's "digest-uri" values can be set using
the "--auth-extra" option. For instance, you could create the
digest-uri-value of "lmtp/mail.example.com/example.com" with the
option "--auth-extra
dmd5-serv-type=lmtp,dmd5-host=mail.example.com,dmd5-serv-name=example.com".
The "digest-uri-value" string and its components is defined in
RFC2831. If none of these values are given, reasonable defaults
will be used.
CRAM-SHA1
The CRAM-SHA1 authenticator requires the Digest::SHA module.
This type has only been tested against a non-standard
implementation on an Exim server and may therefore have some
implementation deficiencies.
NTLM/SPA/MSN
These authenticators require the Authen::NTLM module. This type
has been tested against Exim, Communigate, and Exchange 2007.
In addition to the standard username and password, this
authentication type can also recognize a "domain". The domain
can be set using the "--auth-extra" "domain" keyword. Note that
this has never been tested with a mail server that doesn't
ignore DOMAIN so this may be implemented incorrectly.
-ao, --auth-optional [<auth-type>[,<auth-type>[,...]]]
This option behaves identically to "--auth" except that it requests
authentication rather than requiring it. If no common auth-types
are found or no credentials succeed, Swaks proceeds as if
authentication had not been requested. (Arg-Optional)
-aos, --auth-optional-strict [<auth-type>[,<auth-type>[,...]]]
This option is a compromise between "--auth" and "--auth-optional".
If authentication is never attempted (server doesn't advertise
authentication or no common authentication types are found), it
behaves like "--auth-optional" and the smtp transaction continues.
If authentication is attempted but fails, it behaves like "--auth"
and exits with an error. (Arg-Optional)
-au, --auth-user [<username>]
Provide the username to be used for authentication. If no username
is provided, indicate that Swaks should attempt to find the username
via .netrc (requires the Net::Netrc module). If no username is
provided and cannot be found via .netrc, the user will be prompted
to provide one. The string "<>" can be supplied to mean an empty
username. (Arg-Required, From-Prompt)
-ap, --auth-password [<password>]
Provide the password to be used for authentication. If no password
is provided, indicate that Swaks should attempt to find the password
via .netrc (requires the Net::Netrc module). If no password is
provided and cannot be found via .netrc, the user will be prompted
to provide one. The string "<>" can be supplied to mean an empty
password. (Arg-Required, From-Prompt, Sensitive)
-ae, --auth-extra <key-value-pair>[,<key-value-pair>[,...]]
Some of the authentication types allow extra information to be
included in the authentication process. Rather than add a new
option for every nook and cranny of each authenticator, the
"--auth-extra" option allows this information to be supplied. The
format for <key-value-pair> is KEYWORD=VALUE. (Arg-Required)
The following table lists the currently recognized keywords and the
authenticators that use them
realm, domain
The realm and domain keywords are synonymous. Using either will
set the "domain" option in NTLM/MSN/SPA and the "realm" option
in DIGEST-MD5
dmd5-serv-type
The dmd5-serv-type keyword is used by the DIGEST-MD5
authenticator and is used, in part, to build the digest-uri-
value string (see RFC2831)
dmd5-host
The dmd5-host keyword is used by the DIGEST-MD5 authenticator
and is used, in part, to build the digest-uri-value string (see
RFC2831)
dmd5-serv-name
The dmd5-serv-name keyword is used by the DIGEST-MD5
authenticator and is used, in part, to build the digest-uri-
value string (see RFC2831)
-am, --auth-map <key-value-pair>[,<key-value-pair>[,...]]
Provides a way to map alternate names onto base authentication
types. Useful for any sites that use alternate names for common
types. The format for <key-value-pair> is AUTH-ALIAS=AUTH-TYPE.
This functionality is actually used internally to map types SPA and
MSN onto the base type NTLM. The command line argument to simulate
this would be "--auth-map SPA=NTLM,MSN=NTLM". All of the auth-types
listed above are valid targets for mapping except SPA and MSN. (Arg-
Required)
-apt, --auth-plaintext
Instead of showing AUTH strings base64 encoded as they are
transmitted, translate them to plaintext before printing on screen.
(Arg-None)
-ahp, --auth-hide-password [<replacement-string>]
If this option is specified, any time a readable password would be
printed to the terminal (specifically AUTH PLAIN and AUTH LOGIN) the
password is replaced with the string 'PROVIDED_BUT_REMOVED' (or the
contents of <replacement-string> if provided). The dummy string may
or may not be base64 encoded, contingent on the "--auth-plaintext"
option.
Note that "--auth-hide-password" is similar, but not identical, to
the "--protect-prompt" option. The former protects passwords from
being displayed in the SMTP transaction regardless of how they are
entered. The latter protects sensitive strings when the user types
them at the terminal, regardless of how the string would be used.
(Arg-Optional)
XCLIENT OPTIONS
XCLIENT is an SMTP extension introduced by the Postfix project. XCLIENT
allows a (properly-authorized) client to tell a server to use alternate
information, such as IP address or hostname, for the client. This
allows much easier paths for testing mail server configurations. Full
details on the protocol are available at
<http://www.postfix.org/XCLIENT_README.html>.
The XCLIENT verb can be passed to the server multiple times per SMTP
session with different attributes. For instance, HELO and PROTO might
be passed in one call and NAME and ADDR passed in a second. Because it
can be useful for testing, Swaks exposes some control over how the
attributes are grouped and in what order they are passed to the server.
The different options attempt to expose simplicity for those using Swaks
as a client, and complexity for those using Swaks to test installs.
--xclient-addr [<string>]
--xclient-name [<string>]
--xclient-port [<string>]
--xclient-proto [<string>]
--xclient-destaddr [<string>]
--xclient-destport [<string>]
--xclient-helo [<string>]
--xclient-login [<string>]
--xclient-reverse-name [<string>]
These options specify XCLIENT attributes that should be sent to the
target server. If <string> is not provided, Swaks will prompt and
read the value on "STDIN". See
<http://www.postfix.org/XCLIENT_README.html> for official
documentation for what the attributes mean and their possible
values, including the special "[UNAVAILABLE]" and "[TEMPUNAVAIL]"
values.
By way of simple example, setting "--xclient-name foo.example.com
--xclient-addr 192.168.1.1" will cause Swaks to send the SMTP
command "XCLIENT NAME=foo.example.com ADDR=192.168.1.1".
Note that the "REVERSE_NAME" attribute doesn't seem to appear in the
official documentation. There is a mailing list thread that
documents it, viewable at
<http://comments.gmane.org/gmane.mail.postfix.user/192623>.
These options can all be mixed with each other, and can be mixed
with the "--xclient" option (see below). By default all attributes
will be combined into one XCLIENT call, but see "--xclient-delim".
(Arg-Required, From-Prompt)
--xclient-delim
When this option is specified, it indicates a break in XCLIENT
attributes to be sent. For instance, setting "--xclient-helo 'helo
string' --xclient-delim --xclient-name foo.example.com
--xclient-addr 192.168.1.1" will cause Swaks to send two XCLIENT
calls, "XCLIENT HELO=helo+20string" and "XCLIENT
NAME=foo.example.com ADDR=192.168.1.1". This option is ignored
where it doesn't make sense (at the start or end of XCLIENT options,
by itself, consecutively, etc). (Arg-None)
--xclient [<string>]
This is the "free form" XCLIENT option. Whatever value is provided
for <string> will be sent verbatim as the argument to the XCLIENT
SMTP command. For example, if "--xclient 'NAME= ADDR=192.168.1.1
FOO=bar'" is used, Swaks will send the SMTP command "XCLIENT NAME=
ADDR=192.168.1.1 FOO=bar". If no argument is passed on command
line, Swaks will prompt and read the value on STDIN.
The primary advantage to this over the more specific options above
is that there is no XCLIENT syntax validation here. This allows you
to send invalid XCLIENT to the target server for testing.
Additionally, at least one MTA (Message Systems' Momentum, formerly
ecelerity) implements XCLIENT without advertising supported
attributes. The "--xclient" option allows you to skip the
"supported attributes" check when communicating with this type of
MTA (though see also "--xclient-no-verify").
The "--xclient" option can be mixed freely with the "--xclient-*"
options above. The argument to "--xclient" will be sent in its own
command group. For instance, if "--xclient-addr 192.168.0.1
--xclient-port 26 --xclient 'FOO=bar NAME=wind'" is given to Swaks,
"XCLIENT ADDR=192.168.0.1 PORT=26" and "XCLIENT FOO=bar NAME=wind"
will both be sent to the target server. (Arg-Required, From-Prompt)
--xclient-no-verify
Do not enforce the requirement that an XCLIENT attribute must be
advertised by the server in order for Swaks to send it in an XCLIENT
command. This is to support servers which don't advertise the
attributes but still support them. (Arg-None)
--xclient-before-starttls
If Swaks is configured to attempt both XCLIENT and STARTTLS, it will
do STARTTLS first. If this option is specified it will attempt
XCLIENT first. (Arg-None)
--xclient-optional
--xclient-optional-strict
In normal operation, setting one of the "--xclient*" options will
require a successful XCLIENT transaction to take place in order to
proceed (that is, XCLIENT needs to be advertised, all the user-
requested attributes need to have been advertised, and the server
needs to have accepted Swaks' XCLIENT request). These options
change that behavior. "--xclient-optional" tells Swaks to proceed
unconditionally past the XCLIENT stage of the SMTP transaction,
regardless of whether it was successful.
"--xclient-optional-strict" is similar but more granular. The
strict version will continue to XCLIENT was not advertised, but will
fail if XCLIENT was attempted but did not succeed. (Arg-None)
PROXY OPTIONS
Swaks implements the Proxy protocol as defined in
<http://www.haproxy.org/download/1.5/doc/proxy-protocol.txt>. Proxy
allows an application load balancer, such as HAProxy, to be used in
front of an MTA while still allowing the MTA access to the originating
host information. Proxy support in Swaks allows direct testing of an
MTA configured to expect requests from a proxy, bypassing the proxy
itself during testing.
Swaks makes no effort to ensure that the Proxy options used are
internally consistent. For instance, "--proxy-family" (in version 1) is
expected to be one of "TCP4" or "TCP6". While it will likely not make
sense to the target server, Swaks makes no attempt to ensure that
"--proxy-source" and "--proxy-dest" are in the same protocol family as
"--proxy-family" or each other.
The "--proxy" option is mutually exclusive with all other "--proxy-*"
options except "--proxy-version".
When "--proxy" is not used, all of "--proxy-family", "--proxy-source",
"--proxy-source-port", "--proxy-dest", and "--proxy-dest-port" are
required. Additionally, when "--proxy-version" is 2, "--proxy-protocol"
and "--proxy-command" are optional.
--proxy-version [ 1 | 2 ]
Whether to use version 1 (human readable) or version 2 (binary) of
the Proxy protocol. Version 1 is the default. Version 2 is only
implemented through the "address block", and is roughly on par with
the information provided in version 1. (Arg-Required, From-Prompt)
--proxy [<string>]
This option provides the raw proxy string which will be sent to the
server. The protocol prefix ("PROXY " for version 1, the 12-byte
protocol header for version 2) can be present or not in the
argument. This option allows sending incomplete or malformed Proxy
strings to a target server for testing. This option is mutually
exclusive with all other "--proxy-*" options which provide granular
proxy information.
Because version 2 of the Proxy protocol is a binary protocol, there
are multiple ways to provide the argument to this option. If the
argument starts with "base64:", that prefix is stripped and the rest
of the string is base64 decoded before use. If the argument starts
with "@" it will be treated as a filename and the proxy value will
be read from the file. Any other value is assumed to be the literal
value for the proxy string. (Arg-Required, From-Prompt, From-File)
--proxy-family [<string>]
For version 1, specifies both the address family and transport
protocol. The protocol defines TCP4 and TCP6.
For version 2, specifies only the address family. The protocol
defines AF_UNSPEC, AF_INET, AF_INET6, and AF_UNIX. (Arg-Required,
From-Prompt)
--proxy-protocol [<string>]
For version 2, specifies the transport protocol. The protocol
defines UNSPEC, STREAM, and DGRAM. The default is STREAM. This
option is unused in version 1. (Arg-Required, From-Prompt)
--proxy-command [<string>]
For version 2, specifies the transport protocol. The protocol
defines LOCAL and PROXY. The default is PROXY. This option is
unused in version 1. (Arg-Required, From-Prompt)
--proxy-source [<string>]
Specify the source address of the proxied connection. (Arg-Required,
From-Prompt)
--proxy-source-port [<string>]
Specify the source port of the proxied connection. (Arg-Required,
From-Prompt)
--proxy-dest [<string>]
Specify the destination address of the proxied connection. (Arg-
Required, From-Prompt)
--proxy-dest-port [<string>]
Specify the destination port of the proxied connection. (Arg-
Required, From-Prompt)
DATA OPTIONS
These options pertain to the contents for the DATA portion of the SMTP
transaction. By default a very simple message is sent. If the
"--attach" or "--attach-body" options are used, Swaks attempts to
upgrade to a MIME message.
-d, --data [<data-portion>]
Use argument as the entire contents of DATA.
If no argument is provided, user will be prompted to supply value.
If the argument "-" is provided the data will be read from "STDIN"
with no prompt.
If the argument starts with "@" it will be treated as a filename.
If you would like to pass in an argument that starts with "@" and
isn't a filename, prefix the argument with an additional "@". For
example, "@file.txt" will force processing of file.txt. @@data will
use the string '@data'.
If the argument does not contain any literal (0x0a) or
representative (0x5c, 0x6e or %NEWLINE%) newline characters, it will
be treated as a filename. If the file is open-able, the contents of
the file will be used as the data portion. If the file cannot be
opened, Swaks will error and exit. The entire behavior described in
this paragraph is deprecated and will be removed in a future
release. Instead use a leading "@" to explicitly set that the
argument is a filename.
Any other argument will be used as the DATA contents.
The value can be on one single line, with "\n" (ASCII 0x5c, 0x6e)
representing where line breaks should be placed. Leading dots will
be quoted. Closing dot is not required but is allowed. The default
%FROM_ADDRESS%\nSubject: test %DATE%\nMessage-Id:
<%MESSAGEID%>\nX-Mailer: swaks v%SWAKS_VERSION%
jetmore.org/john/code/swaks/\n%NEW_HEADERS%\n%BODY%\n".
Very basic token parsing is performed on the DATA portion. The
following table shows the recognized tokens and their replacement
values. (Arg-Required, From-Prompt, From-File)
%FROM_ADDRESS%, ..FROM_ADDRESS..
Replaced with the envelope-sender.
%TO_ADDRESS%, ..TO_ADDRESS..
Replaced with the envelope-recipient(s) set by the "--to"
option.
%CC_ADDRESS%, ..CC_ADDRESS..
Replaced with the envelope-recipient(s) set by the "--cc"
option.
%BCC_ADDRESS%, ..BCC_ADDRESS..
Replaced with the envelope-recipient(s) set by the "--bcc"
option.
%DATE%, ..DATE..
Replaced with the current time in a format suitable for
standard module POSIX for timezone calculations. If this module
is unavailable or the current environment doesn't support the %z
strftime format token (as on Windows) the date string will be in
GMT.
%MESSAGEID%, ..MESSAGEID..
Replaced with a message ID string suitable for use in a Message-
Id header. The value for this token will remain consistent for
the life of the process.
%SWAKS_VERSION%, ..SWAKS_VERSION..
Replaced with the version of the currently-running Swaks
process.
%NEW_HEADERS%, ..NEW_HEADERS..
Replaced with the contents of the "--add-header" option. If
"--add-header" is not specified this token is simply removed.
%BODY%, ..BODY..
Replaced with the value specified by the "--body" option. See
"--body" for default.
%NEWLINE%, ..BODY..
Replaced with carriage return, newline (0x0d, 0x0a). This is
identical to using "\n" (0x5c, 0x6e), but doesn't have the
escaping concerns that the backslash can cause on the newline.
-dab, --dump-as-body [<section>[,<section>[,...]]]
If "--dump-as-body" is used and no other option is used to change
the default body of the message, the body is replaced with output
similar to the output of what is provided by "--dump". "--dump"'s
initial program capability stanza is not displayed, and the "data"
section is not included. Additionally, "--dump" always includes
passwords. By default "--dump-as-body" does not include passwords,
though this can be changed with "--dump-as-body-shows-password".
"--dump-as-body" takes the same arguments as "--dump" except the
SUPPORT and DATA arguments are not supported. (Arg-Optional)
-dabsp, --dump-as-body-shows-password
Cause "--dump-as-body" to include plaintext passwords. This option
is not recommended. This option implies "--dump-as-body". (Arg-
None)
--body [<body-specification>]
Specify the body of the email. The default is "This is a test
mailing". If no argument to "--body" is given, prompt to supply one
interactively. If "-" is supplied, the body will be read from
standard input. Arguments beginning with "@" will be treated as
filenames containing the body data to use (see "--data" for more
detail).
If, after the above processing, the argument represents an open-able
file, the content of that file is used as the body. This is
deprecated behavior and will be removed in a future release.
Instead use a leading "@" to explicitly set that the argument is a
filename.
If the message is forced to MIME format (see "--attach") "--body
'body text'" is the same as "--attach-type text/plain --attach-body
'body text'". See "--attach-body" for details on creating a
multipart/alternative body. (Arg-Required, From-Prompt, From-File)
--attach [<attachment-specification>]
When one or more "--attach" option is supplied, the message is
changed into a multipart/mixed MIME message. The arguments to
"--attach" are processed the same as "--body" with respect to
"STDIN", file contents, etc. "--attach" can be supplied multiple
times to create multiple attachments. By default, each attachment
is attached as an application/octet-stream file. See
"--attach-type" for changing this behavior.
If the contents of the attachment are provided via a file name, the
MIME encoding will include that file name. See "--attach-name" for
more detail on file naming.
It is legal for "-" ("STDIN") to be specified as an argument
multiple times (once for "--body" and multiple times for
"--attach"). In this case, the same content will be attached each
time it is specified. This is useful for attaching the same content
with multiple MIME types. (Arg-Required, From-File)
--attach-body [<body-specification>]
This is a variation on "--attach" that is specifically for the body
part of the email. It behaves identically to "--attach" in that it
takes the same arguments and forces the creation of a MIME message.
However, it is different in that the argument will always be the
first MIME part in the message, no matter where in option processing
order it is encountered. Additionally, "--attach-body" options
stack to allow creation of multipart/alternative bodies. For
example, "--attach-type text/plain --attach-body 'plain text body'
--attach-type text/html --attach-body 'html body'" would create a
multipart/alternative message body. (Arg-Required, From-File)
--attach-type <mime-type>
By default, content that gets MIME attached to a message with the
"--attach" option is encoded as application/octet-stream (except for
the body, which is text/plain by default). "--attach-type" changes
the mime type for every "--attach" option which follows it. It can
be specified multiple times. The current MIME type gets reset to
application/octet-stream between processing body parts and other
parts. (Arg-Required)
--attach-name [<name>]
This option sets the filename that will be included in the MIME part
created for the next "--attach" option. If no argument is set for
this option, it causes no filename information to be included for
the next MIME part, even if Swaks could generate it from the local
file name. (Arg-Optional)
-ah, --add-header <header>
This option allows headers to be added to the DATA. If
"%NEW_HEADERS%" is present in the DATA it is replaced with the
argument to this option. If "%NEW_HEADERS%" is not present, the
argument is inserted between the first two consecutive newlines in
the DATA (that is, it is inserted at the end of the existing
headers).
The option can either be specified multiple times or a single time
with multiple headers separated by a literal "\n" string. So,
"--add-header 'Foo: bar' --add-header 'Baz: foo'" and "--add-header
'Foo: bar\nBaz: foo'" end up adding the same two headers. (Arg-
Required)
--header <header-and-data>, --h-<header> <data>
These options allow a way to change headers that already exist in
the DATA. "--header 'Subject: foo'" and "--h-Subject foo" are
equivalent. If the header does not already exist in the data then
this argument behaves identically to "--add-header". However, if
the header already exists it is replaced with the one specified.
Negating the version of this option with the header name in the
option (eg "--no-header-Subject") will remove all previously
processed "--header" options, not just the ones used for 'Subject'.
Embedding the header name in the option via environment variable is
not supported on Windows and will result in an error. (Arg-Required)
-g This option is a direct alias to "--data -" (read DATA from
"STDIN"). It is totally secondary to "--data". Any occurrence of
"--data" will cause "-g" to be ignored. This option cannot be
negated with the "no-" prefix. This option is deprecated and will
be removed in a future version of Swaks. (Arg-None, Deprecated)
--no-data-fixup, -ndf
This option forces Swaks to do no massaging of the DATA portion of
the email. This includes token replacement, From_ stripping,
trailing-dot addition, "--body"/attachment inclusion, and any header
additions. This option is only useful when used with "--data",
since the internal default DATA portion uses tokens. (Arg-None)
--no-strip-from, -nsf
Don't strip the From_ line from the DATA portion, if present. (Arg-
None)
OUTPUT OPTIONS
Swaks provides a transcript of its transactions to its caller
("STDOUT"/"STDERR") by default. This transcript aims to be as faithful
a representation as possible of the transaction though it does modify
this output by adding informational prefixes to lines and by providing
plaintext versions of TLS transactions
The "informational prefixes" are referred to as transaction hints.
These hints are initially composed of those marking lines that are
output of Swaks itself, either informational or error messages, and
those that indicate a line of data actually sent or received in a
transaction. This table indicates the hints and their meanings:
"==="
Indicates an informational line generated by Swaks.
"***"
Indicates an error generated within Swaks.
" ->"
Indicates an expected line sent by Swaks to target server.
" ~>"
Indicates a TLS-encrypted, expected line sent by Swaks to target
server.
"**>"
Indicates an unexpected line sent by Swaks to the target server.
"*~>"
Indicates a TLS-encrypted, unexpected line sent by Swaks to target
server.
" >"
Indicates a raw chunk of text sent by Swaks to a target server (see
"--show-raw-text"). There is no concept of "expected" or
"unexpected" at this level.
"<- "
Indicates an expected line sent by target server to Swaks.
"<~ "
Indicates a TLS-encrypted, expected line sent by target server to
Swaks.
"<**"
Indicates an unexpected line sent by target server to Swaks.
"<~*"
Indicates a TLS-encrypted, unexpected line sent by target server to
Swaks.
"< "
Indicates a raw chunk of text received by Swaks from a target server
(see "--show-raw-text"). There is no concept of "expected" or
"unexpected" at this level.
The following options control what and how output is displayed to the
caller.
-n, --suppress-data
Summarizes the DATA portion of the SMTP transaction instead of
printing every line. This option is very helpful, bordering on
required, when using Swaks to send certain test emails. Emails with
attachments, for instance, will quickly overwhelm a terminal if the
DATA is not suppressed. (Arg-None)
-stl, --show-time-lapse [i]
Display time lapse between send/receive pairs. This option is most
useful when Time::HiRes is available, in which case the time lapse
will be displayed in thousandths of a second. If Time::HiRes is
unavailable or "i" is given as an argument the lapse will be
displayed in integer seconds only. (Arg-Optional)
Don't display the transaction hint for informational transactions.
This is most useful when needing to copy some portion of the
informational lines, for instance the certificate output from
"--tls-get-peer-cert". (Arg-None)
-nih, --no-info-hints
-nsh, --no-send-hints
-nrh, --no-receive-hints
-nth, --no-hints
"--no-info-hints", "--no-send-hints", and "--no-receive-hints"
suppress the transaction hints from info, send, and receive lines,
respectively. This is often useful when copying some portion of the
transaction for use elsewhere (for instance, "--no-send-hints
--hide-receive --hide-informational" is a useful way to get only the
client-side commands for a given transaction and "--no-info-hints
--tls-get-peer-cert" for copying the peer certificate).
"--no-hints" is identical to specifying "--no-info-hints
--no-send-hints --no-receive-hints". (Arg-None)
-raw, --show-raw-text
This option will print a hex dump of raw data sent and received by
Swaks. Each hex dump is the contents of a single read or write on
the network. This should be identical to what is already being
displayed (with the exception of the "\r" characters being removed).
This option is useful in seeing details when servers are sending
lots of data in single packets, or breaking up individual lines into
multiple packets. If you really need to go in depth in that area
you're probably better with a packet sniffer, but this option is a
good first step to seeing odd connection issues. (Arg-None)
--output, --output-file <file-path>
--output-file-stdout <file-path>
--output-file-stderr <file-path>
These options allow the user to send output to files instead of
"STDOUT"/"STDERR". The first option sends both to the same file.
The arguments of &STDOUT and &STDERR are treated specially,
referring to the "normal" file handles, so "--output-file-stderr
'&STDOUT'" would redirect "STDERR" to "STDOUT". These options are
honored for all output except "--help" and "--version". (Arg-
Required)
-pp, --protect-prompt
Don't echo user input on prompts that are potentially sensitive
(right now only authentication password). Very specifically, any
option which is marked 'Sensitive' and eventually prompts for an
argument will do its best to mask that argument from being echoed.
See also "--auth-hide-password". (Arg-None)
-hr, --hide-receive
Don't display lines sent from the remote server being received by
Swaks. (Arg-None)
-hs, --hide-send
Don't display lines being sent by Swaks to the remote server. (Arg-
None)
-hi, --hide-informational
Don't display non-error informational lines from Swaks itself. (Arg-
None)
-ha, --hide-all
Do not display any content to the terminal. (Arg-None)
-S, --silent [ 1 | 2 | 3 ]
Cause Swaks to be silent. If no argument is given or if an argument
of "1" is given, print no output unless/until an error occurs, after
which all output is shown. If an argument of "2" is given, only
print errors. If "3" is given, show no output ever. "--silent"
affects most output but not all. For instance, "--help",
"--version", "--dump", and "--dump-mail" are not affected. For
historical reasons, -S is not settable via environment variable on
Windows, use SWAKS_OPT_silent instead. (Arg-Optional)
--support
Print capabilities and exit. Certain features require non-standard
Perl modules. This option evaluates whether these modules are
present and displays which functionality is available and which
isn't, and which modules would need to be added to gain the missing
functionality. (Arg-None)
--dump-mail
Cause Swaks to process all options to generate the message it would
send, then print that message to "STDOUT" instead of sending it.
This output is identical to the "data" section of "--dump", except
without the trailing dot. (Arg-None)
--dump [<section>[,<section>[,...]]]
This option causes Swaks to print the results of option processing,
immediately before mail would have been sent. No mail will be sent
when "--dump" is used. Note that "--dump" is a pure self-diagnosis
tool and no effort is made or will ever be made to mask passwords in
the "--dump" output. If a section is provided as an argument to this
option, only the requested section will be shown. Currently
supported arguments are SUPPORT, APP, OUTPUT, TRANSPORT, PROTOCOL,
XCLIENT, PROXY, TLS, AUTH, DATA, and ALL. If no argument is
provided, all sections are displayed (Arg-Optional)
--help
Display this help information and exit. (Arg-None)
--version
Display version information and exit. (Arg-None)
DEPRECATIONS
The following features are deprecated and will be removed in a future
version of Swaks
use of IO::Socket and IO::Socket::INET6 modules
Will be removed no sooner than (February 1, 2025).
The primary method of sending over IPv4 and IPv6 sockets is
implemented with the IO::Socket::IP module. For the time being
there is still legacy support of the IO::Socket and
IO::Socket::INET6 modules which were previously used. Please ensure
IO::Socket::IP is installed to ensure future functionality.
PORTABILITY
OPERATING SYSTEMS
This program was primarily intended for use on UNIX-like operating
systems, and it should work on any reasonable version thereof. It
has been developed and tested on Solaris, Linux, and Mac OS X and is
feature complete on all of these.
This program is known to demonstrate basic functionality on Windows
using Strawberry Perl. In all documentation, unless otherwise
noted, "Windows" refers to running Swaks via CMD.exe, not WSL or
cygwin. It has not been fully tested, but known to work are basic
SMTP functionality and the LOGIN, PLAIN, and CRAM-MD5 auth types.
Unknown is any TLS functionality and the NTLM/SPA and DIGEST-MD5
auth types. Some functionality is known to be limited on Windows,
including inability to embed header name in environment variables
(see "CONFIGURATION ENVIRONMENT VARIABLES" and "--header"),
inability to generate a local-timezone date string (see "%DATE%"
token under "--data"), inability to use "-S" option as an
environment variable (see "--silent"), and inability to have a "set
but empty" value in an environment variable (see "CONFIGURATION
ENVIRONMENT VARIABLES" for workaround).
Because this program should work anywhere Perl works, I would
appreciate knowing about any new operating systems you've thoroughly
used Swaks on as well as any problems encountered on a new OS.
MAIL SERVERS
This program was almost exclusively developed against Exim mail
servers. It has been used casually by the author, though not
thoroughly tested, with Sendmail, Smail, Exchange, Oracle
Collaboration Suite, qpsmtpd, and Communigate. Because all
functionality in Swaks is based on known standards it should work
with any fairly modern mail server. If a problem is found, please
alert the author at the address below.
ENVIRONMENT VARIABLES
LOGNAME
If Swaks must create a sender address, $LOGNAME is used as the
message local-part if it is set, and unless "--force-getpwuid" is
used.
SWAKS_HOME
Used when searching for a .swaksrc configuration file. See OPTION
PROCESSING -> "CONFIGURATION FILES" above.
SWAKS_OPT_*
Environment variable prefix used to specify Swaks options from
environment variables. See OPTION PROCESSING -> "CONFIGURATION
ENVIRONMENT VARIABLES" above.
EXIT CODES
0 no errors occurred
1 error parsing command line options
2 error connecting to remote server
3 unknown connection type
4 while running with connection type of "pipe", fatal problem writing
to or reading from the child process
5 while running with connection type of "pipe", child process died
unexpectedly. This can mean that the program specified with
"--pipe" doesn't exist.
6 Connection closed unexpectedly. If the close is detected in
response to the 'QUIT' Swaks sends following an unexpected response,
the error code for that unexpected response is used instead. For
instance, if a mail server returns a 550 response to a MAIL FROM:
and then immediately closes the connection, Swaks detects that the
connection is closed, but uses the more specific exit code 23 to
detail the nature of the failure. If instead the server return a
250 code and then immediately closes the connection, Swaks will use
the exit code 6 because there is not a more specific exit code.
10 error in prerequisites (needed module not available)
21 error reading initial banner from server
22 error in HELO transaction
23 error in MAIL transaction
24 no RCPTs accepted
25 server returned error to DATA request
26 server did not accept mail following data
27 server returned error after normal-session quit request
28 error in AUTH transaction
29 error in TLS transaction
30 PRDR requested/required but not advertised
32 error in EHLO following TLS negotiation
33 error in XCLIENT transaction
34 error in EHLO following XCLIENT
35 error in PROXY option processing
36 error sending PROXY banner
ABOUT THE NAME
The name "Swaks" is a (sort-of) acronym for "SWiss Army Knife SMTP". It
was chosen to be fairly distinct and pronounceable. While "Swaks" is
unique as the name of a software package, it has some other, non-
software meanings. Please send in other uses of "swak" or "swaks" for
inclusion.
"Sealed With A Kiss"
SWAK/SWAKs turns up occasionally on the internet with the meaning
"with love".
bad / poor / ill (Afrikaans)
Seen in the headline "SA se bes en swaks gekledes in 2011", which
was translated as "best and worst dressed" by native speakers.
Google Translate doesn't like "swaks gekledes", but it will
translate "swak" as "poor" and "swak geklede" as "ill-dressed".
LICENSE
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
CONTACT INFORMATION
General contact, questions, patches, requests, etc to
[email protected].
Change logs, this help, and the latest version are found at
<http://www.jetmore.org/john/code/swaks/>.
Swaks is crafted with love by John Jetmore from the cornfields of
Indiana, United States of America.
NOTIFICATIONS
Email
[email protected]
If you would like to be put on a list to receive notifications when
a new version of Swaks is released, please send an email to this
address. There will not be a response to your email.
Website
<http://www.jetmore.org/john/blog/c/swaks/>
RSS Feed
<http://www.jetmore.org/john/blog/c/swaks/feed/>
Twitter
<http://twitter.com/SwaksSMTP>
perl v5.36.0 2024-01-05 SWAKS(1)
Updated on: 2024-May-23