Free smtp port software for linux

ClamSMTP project is an SMTP filter that allows you to check for viruses using the ClamAV anti-virus software.
It accepts SMTP connections and forwards the SMTP commands and responses to another SMTP server. The DATA email body is intercepted and scanned before forwarding.
ClamSMTP aims to be lightweight, reliable, and simple rather than have a myriad of options. Its written in C without major dependencies. If you need more options then you could use something big like AMaViS which is written in PERL and can do almost anything.
I wrote this with the Postfix mail server in mind. Heres how to configure it as a Postfix Content Filter.
ClamSMTP can also be used as a transparent proxy to filter an entire networks SMTP traffic at the router.
Enhancements:
- Support has been removed for listening on ports under 1024.
- Support has been added for embedded NULLs in email data.
- Problems with not listening properly when in daemon mode have been fixed, as well as warnings when compiled with gcc 4.0.
- Empty addresses are handled properly in logs.
- This release will not let Exchange send its strange binary data through the proxy.
- More Solaris fixes.
- Email messages are not rejected when the server is overloaded or encounters errors, or when starting the filter command fails.

TCP port scanner is a network scanner for Linux.

Installation:

1. Install - become root and gunzip/tar tcpscan-X-Y-Z.tar.gz.
2. Type ./confugure , make
3. Type install
4. Enjoy and try type tcpscan localhost
5. To get help - run tcpscan without parametres.

Usage:

tcpscan [-f] [hostname || IP_address]
tcpscan [-f] [first_IP_address] [last_IP_address]

DGS SMTP is a PHP class which acts as an email client, able to send an email without using PHPs built in mail() function.

This is most often useful for sites that are unable to get PHPs build in mail() function to work. (Usually because they dont have access to sites php.ini file).

SMTarPit is a chrooted SMTP honeypot and tarpit.

I wrote this program because I looked around the Internet for an SMTP Tarpit/Honeypot that was: written in Perl; and, was only an SMTP tarpit/honeypot - I couldnt find one.

SMTarPit is a combined SMTP honey 7187 7187pot and tarpit released under the GPL. It is writen in Perl so it should work on virtually any platform that supports Perl (except Windows). It uses xinetd which looks at port 25 (instructions in the tarball) and when someone calls it, smtarpit is launched and then it chroots itself. It then decides whether there is a man or a machine on the other end and sets about wasting their time.

There are plenty of instructions as to how to configure the program - if Perl is not your first language, you should still be able to see what to do. You will certainly need to put a valid domain name in there but it is all well laid out so that you can install it and run it as a part of xinetd.

If you are an ISP with a tarpitted connection, you can tell which one it is from the fact that the tarpitted connection has a paritcular profile of inactivity and persistancy that no normal SMTP connection has. With this in mind, you can look at your RADIUS logs and take action on the spammer - the one thing that you know from monitoring the connection is that there will be many mails to the same domain from the same source address and that none of them will be solicited as there is in reality nobody to solicit them.

Unsolicited bulk email equals spam and with the RADIUS logs, you can notify the authorities and have the spammer arrested and procecuted - or do nothing more than throw them off and let them spam another day. All spam connections are logged by the tarpit.

How does it work?

Every time an incoming call to port 25 happens, xinetd starts a copy of this server. It only has a small memory footprint and doesnt really consume much processor time.
When the server is started, it responds with the usual welcome message and then waits for the client to respond. When the client does respond, it looks at how long it took and tries to work out whether it is a man or machine at the other end (you can adjust this time in the program if you want).

If the server thinks that it is a machine at the other end, it goes into tarpit mode where everything takes a long time. In SMTP, the server response codes have a three figure number and if that is followed by a dash (-), the client has to wait until it receives one with a space after it. This can take an hour or so.

There are time-outs but you can make the response times all different to avoid profiling/finger-printing of the server - SMTarPit can do this automatically. While all of this is going on, the server is just sitting there, asleep. It doesnt take any significant processor time (arguably any at all) and only a few kB in memory. You can limit the number of concurrent servers with xinetd (explanation and example in the program file at the beginning) and impose any other limitations you want.

In other words, this server allows you to tarpit (stall) several spamming processes (up to the limit you define in the program and your xinetd configuration files) for hours at a time with only minor resource consumption on your part. You certainly wont see any bandwidth eaten away by it (50 Bytes per minute on average is typical).

smtptools is a collection of tools to send or receive mails with the simple mail transfer protocol.
maildirblast
may be used to send some or all messages from a maildir to a preconfigured relay host or the official mail exchanger hosts of the recipient addresses. maildirblasts functions partially overlap with those of maildirsmtp from Daniel Bernsteins serialmail package.
smtpblast
sends a single message with SMTP to a configured relay host or to a MX host. It uses the qmail return codes and may be used to bypass a broken mail system or, with for example ssh port forwarding, even some firewalls.
tomaildir
is a simple tool to write a message into a maildir. It uses the qmail return codes (see the dot-qmail manual page for more information). (yes, this has nothing todo with SMTP. But i find it useful anyway)
Main features:
- logging (qmail-smtpd basically has no logging)
- more finegrained relay control, its possibly to allow relaying for *.domain.example, but not for bad.domain.example. Its possible to deny delivery to certain addresses.
- built in RBL support
- check for existence of envelope sender domain.

smtp_wrapper is a daemon program that acts as an SMTP proxy for Unix-like systems. smtp_wrapper project supports SMTP filtering of spam.
Usage:
smtp_wrapper [-mh hostname] [-mp port] [-q backlog]
[-sh smtpserver_hostname] [-sp smtpserver_port]
[-t timeout_sec] [-d delay_sec] [-if ip_filter]
[-f contents_filter] [-cm child_max] [-i minimum_interval_sec]
[-F]
-mh hostname : my hostname [ANY]
-mp port : my port [25]
-q backlog : socket queue number [5]
-sh smtpserver_hostname : real smtp hostname [localhost]
-sp smtpserver_port : real smtp port [8025]
-t timeout_sec : timeout second [no timeout]
-d delay_sec : delay second for initial connection [0]
-if ip_filter : filter program for IP check [/usr/local/smtp_wrapper/smtp_ip_filter]
-f contents_filter : filter program for contents check [/usr/local/smtp_wrapper/smtp_contents_filter]
-cm child_max : max number of connection to real smtp daemon [10]
-i minimum_interval_sec : minimum interval second of connection from same ip address [0]
-F : run in foreground
Enhancements:
- This release adds -nsc (no sequence check).
- It adds a sample filter script.
- There are minor bugfixes and some enhancements.

Postfix SMTP Monitoring Solution is a set of three Perl CGI scripts used to monitor the SMTP queue, allowing the deletion of messages that for one reason or another become "stuck" in the queue.

I needed a web-based solution to monitor my Postfix SMTP relay, which enabled me to remove messages that become "stuck" in the queue. I wrote three simple Perl scripts, and used Sudo to give me the desired functionality.

I am uploading these scripts in case they are useful to others. Assuming you have Apache configured correctly on your Postfix server, it should be as easy as placing the three .cgi files into your webservers cgi-bin directory, and making the appropriate modifications to your /etc/sudoers file (see the README contained in the tarball).

smtp-vilter is a high-performance content filter for sendmail, which detects email viruses and spam.

smtp-vilter can pass, discard, or simply mark an email based on the results of a content scan. It relies on third-party products for the actual content scan. It uses the milter API to communicate with sendmail, and backends to communicate with the actual scanning engines.

The backends can be chained to perform a series of checks on each message in one run.