Postfix: smtp-sink
Revision as of 16:52, 8 June 2015 by Onnowpurbo (talk | contribs)
SMTP-SINK(1) SMTP-SINK(1)
NAME
smtp-sink - parallelized SMTP/LMTP test server
SYNOPSIS
smtp-sink [options] [inet:][host]:port backlog
smtp-sink [options] unix:pathname backlog
DESCRIPTION
smtp-sink listens on the named host (or address) and port. It takes
SMTP messages from the network and throws them away. The purpose is to
measure client performance, not protocol compliance.
smtp-sink may also be configured to capture each mail delivery transac-
tion to file. Since disk latencies are large compared to network
delays, this mode of operation can reduce the maximal performance by
several orders of magnitude.
Connections can be accepted on IPv4 or IPv6 endpoints, or on
UNIX-domain sockets. IPv4 and IPv6 are the default. This program is
the complement of the smtp-source(1) program.
Note: this is an unsupported test program. No attempt is made to main-
tain compatibility between successive versions.
Arguments:
-4 Support IPv4 only. This option has no effect when Postfix is
built without IPv6 support.
-6 Support IPv6 only. This option is not available when Postfix is
built without IPv6 support.
-8 Do not announce 8BITMIME support.
-a Do not announce SASL authentication support.
-A delay
Wait delay seconds after responding to DATA, then abort prema-
turely with a 550 reply status. Do not read further input from
the client; this is an attempt to block the client before it
sends ".". Specify a zero delay value to abort immediately.
-b soft-bounce-reply
Use soft-bounce-reply for soft reject responses. The default
reply is "450 4.3.0 Error: command failed".
-B hard-bounce-reply
Use hard-bounce-reply for hard reject responses. The default
reply is "500 5.3.0 Error: command failed".
-c Display running counters that are updated whenever an SMTP ses-
sion ends, a QUIT command is executed, or when "." is received.
-C Disable XCLIENT support.
-d dump-template
Dump each mail transaction to a single-message file whose name
is created by expanding the dump-template via strftime(3) and
appending a pseudo-random hexadecimal number (example:
"%Y%m%d%H/%M." expands into "2006081203/05.809a62e3"). If the
template contains "/" characters, missing directories are cre-
ated automatically. The message dump format is described below.
Note: this option keeps one capture file open for every mail
transaction in progress.
-D dump-template
Append mail transactions to a multi-message dump file whose name
is created by expanding the dump-template via strftime(3). If
the template contains "/" characters, missing directories are
created automatically. The message dump format is described
below.
Note: this option keeps one capture file open for every mail
transaction in progress.
-e Do not announce ESMTP support.
-E Do not announce ENHANCEDSTATUSCODES support.
-f command,command,...
Reject the specified commands with a hard (5xx) error code.
This option implies -p.
Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT,
VRFY, DATA, ., RSET, NOOP, and QUIT. Separate command names by
white space or commas, and use quotes to protect white space
from the shell. Command names are case-insensitive.
-F Disable XFORWARD support.
-h hostname
Use hostname in the SMTP greeting, in the HELO response, and in
the EHLO response. The default hostname is "smtp-sink".
-H delay
Delay the first read operation after receiving DATA (time in
seconds). Combine with a large test message and a small TCP win-
dow size (see the -T option) to test the Postfix client
write_wait() implementation.
-L Enable LMTP instead of SMTP.
-m count (default: 256)
An upper bound on the maximal number of simultaneous connections
that smtp-sink will handle. This prevents the process from run-
ning out of file descriptors. Excess connections will stay
queued in the TCP/IP stack.
-M count
Terminate after receiving count messages.
-n count
Terminate after count sessions.
-N Do not announce support for DSN.
-p Do not announce support for ESMTP command pipelining.
-P Change the server greeting so that it appears to come through a
CISCO PIX system. Implies -e.
-q command,command,...
Disconnect (without replying) after receiving one of the speci-
fied commands.
Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT,
VRFY, DATA, ., RSET, NOOP, and QUIT. Separate command names by
white space or commas, and use quotes to protect white space
from the shell. Command names are case-insensitive.
-Q command,command,...
Send a 421 reply and disconnect after receiving one of the spec-
ified commands.
Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT,
VRFY, DATA, ., RSET, NOOP, and QUIT. Separate command names by
white space or commas, and use quotes to protect white space
from the shell. Command names are case-insensitive.
-r command,command,...
Reject the specified commands with a soft (4xx) error code.
This option implies -p.
Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT,
VRFY, DATA, ., RSET, NOOP, and QUIT. Separate command names by
white space or commas, and use quotes to protect white space
from the shell. Command names are case-insensitive.
-R root-directory
Change the process root directory to the specified location.
This option requires super-user privileges. See also the -u
option.
-s command,command,...
Log the named commands to syslogd.
Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT,
VRFY, DATA, ., RSET, NOOP, and QUIT. Separate command names by
white space or commas, and use quotes to protect white space
from the shell. Command names are case-insensitive.
-S start-string
An optional string that is prepended to each message that is
written to a dump file (see the dump file format description
below). The following C escape sequences are supported: \a
(bell), \b (backspace), \f (formfeed), \n (newline), \r (car-
riage return), \t (horizontal tab), \v (vertical tab), \ddd (up
to three octal digits) and \\ (the backslash character).
-t timeout (default: 100)
Limit the time for receiving a command or sending a response.
The time limit is specified in seconds.
-T windowsize
Override the default TCP window size. To work around broken TCP
window scaling implementations, specify a value > 0 and < 65536.
-u username
Switch to the specified user privileges after opening the net-
work socket and optionally changing the process root directory.
This option is required when the process runs with super-user
privileges. See also the -R option.
-v Show the SMTP conversations.
-w delay
Wait delay seconds before responding to a DATA command.
-W command:delay[:odds]
Wait delay seconds before responding to command. If odds is
also specified (a number between 1-99 inclusive), wait for a
random multiple of delay. The random multiplier is equal to the
number of times the program needs to roll a dice with a range of
0..99 inclusive, before the dice produces a result greater than
or equal to odds.
[inet:][host]:port
Listen on network interface host (default: any interface) TCP
port port. Both host and port may be specified in numeric or
symbolic form.
unix:pathname
Listen on the UNIX-domain socket at pathname.
backlog
The maximum length the queue of pending connections, as defined
by the listen(2) system call.
DUMP FILE FORMAT
Each dumped message contains a sequence of text lines, terminated with
the newline character. The sequence of information is as follows:
o The optional string specified with the -S option.
o The smtp-sink generated headers as documented below.
o The message header and body as received from the SMTP client.
o An empty line.
The format of the smtp-sink generated headers is as follows:
X-Client-Addr: text
The client IP address without enclosing []. An IPv6 address is
prefixed with "ipv6:". This record is always present.
X-Client-Proto: text
The client protocol: SMTP, ESMTP or LMTP. This record is always
present.
X-Helo-Args: text
The arguments of the last HELO or EHLO command before this mail
delivery transaction. This record is present only if the client
sent a recognizable HELO or EHLO command before the DATA com-
mand.
X-Mail-Args: text
The arguments of the MAIL command that started this mail deliv-
ery transaction. This record is present exactly once.
X-Rcpt-Args: text
The arguments of an RCPT command within this mail delivery
transaction. There is one record for each RCPT command, and they
are in the order as sent by the client.
Received: text
A message header for compatibility with mail processing soft-
ware. This three-line header marks the end of the headers pro-
vided by smtp-sink, and is formatted as follows:
from helo ([addr])
The HELO or EHLO command argument and client IP address.
If the client did not send HELO or EHLO, the client IP
address is used instead.
by host (smtp-sink) with proto id random;
The hostname specified with the -h option, the client
protocol (see X-Client-Proto above), and the pseudo-ran-
dom portion of the per-message capture file name.
time-stamp
A time stamp as defined in RFC 2822.
SEE ALSO
smtp-source(1), SMTP/LMTP message generator
LICENSE
The Secure Mailer license must be distributed with this software.
AUTHOR(S)
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
Menjalankan
Now let's turn our attention to smtp-sink to find out how many messages per second your server can handle from your horrible mass mailing sofware. Postfix has to process each outgoing message even if the server on the other side throws it away (therefore, you can't use this to test the raw performance of your mass mailer unless you connect your mailer directly to smtp-sink).
The following example sets up an SMTP listener on port 25 of localhost:
$ ./smtp-sink -c localhost:25 1000
Now you can run your client tests.
If you want to get an idea for how much overhead the network imposes and also get a control experiment to see what the theoretical maximum throughput for a mail server, you can make smtp-source and smtp-sink talk to each other. Open two windows. In the first, start up the dummy server like this:
- ./smtp-sink -c localhost:25 1000
100
With this in place, start throwing messages at this server with smtp-source in the other window:
$ time ./smtp-source -s 20 -l 5120 -m 100 -c \
-f sender@example.com -t recipient@example.com localhost:25
100
real 0m0.239s user 0m0.000s sys 0m0.040s
This output shows that smtp-sink is much faster at accepting messages than Postfix. It took only 0.239 seconds to accept the messages, which is 18 times faster than the Postfix injection process. Now, wouldn't it be nice if you could throw away all incoming email like this?