Nov 152011
 

Someone asked me if i can make a perl scripts that can change the ip address based on time interval, say he want ip address 1.2.3.4 used within one hour, if done next ip address will be used within next one hour..and so on. when it came to highest number of ip address in array, they will be reset back to the start. first i suggest him to look at the articles i wrote. But then i decide to write Perl script which was made for the purposes mention above.

here we are..

Postfix section:

master.cf
127.0.0.1:2527 inet  n       n       n       -       0      spawn
          user=nobody argv=/etc/postfix/ip_by_time.pl

ip1  unix -       -       n       -       -       smtp
          -o syslog_name=postfix-ip1
          -o smtp_helo_name=smtp1.example.com
          -o smtp_bind_address=1.2.3.1

ip2  unix -       -       n       -       -       smtp
          -o syslog_name=postfix-ip2
          -o smtp_helo_name=smtp2.example.com
          -o smtp_bind_address=1.2.3.2

ip3  unix -       -       n       -       -       smtp
          -o syslog_name=postfix-ip3
          -o smtp_helo_name=smtp3.example.com
          -o smtp_bind_address=1.2.3.3

ip4  unix -       -       n       -       -       smtp
          -o syslog_name=postfix-ip4
          -o smtp_helo_name=smtp4.example.com
          -o smtp_bind_address=1.2.3.4
....
....

main.cf

transport_maps = tcp:[127.0.0.1]:2527
127.0.0.1:2527_time_limit = 3600s


Perl section:

#!/usr/bin/perl
use strict;
use warnings;
use Storable;

## interval between ip switchover, one hour for example
my $ip_interval=3600;

my $hashfile="data.hash";
store {}, $hashfile unless -r $hashfile;

my @smtp_array = (
'ip1:',
'ip2:',
'ip3:',
'ip4:',
'ip5:',
'ip6:',
'ip7:',
'ip8:',
'ip9:',
'ip:'
);
# and more ips

#
# Autoflush standard output.
#
select STDOUT; $|++;

while (<>) {
        chomp;
        my $time_stamp = retrieve($hashfile);
        my $now = time();

        if (!defined $time_stamp->{'time_diff'}) {
                $time_stamp->{'time_diff'} = $now;
                $time_stamp->{'ip_index'} = 0;
                store $time_stamp, $hashfile;
        }

        if (/^get\s(.+)$/i) {
                if ($now > $time_stamp->{'time_diff'} + $ip_interval) {
                        if ($time_stamp->{'ip_index'} < scalar(@smtp_array) - 1) {
                                $time_stamp->{'ip_index'}++;
                        } else {
                                $time_stamp->{'ip_index'} = 0;
                        }
                        print "200 $smtp_array[$time_stamp->{'ip_index'}]\n";
                        $time_stamp->{'time_diff'} = $now;
                        store $time_stamp, $hashfile;
                        next;
                } else {
                        print "200 $smtp_array[$time_stamp->{'ip_index'}]\n";
                        next;
                }
        }

        ## default response 
        print "200 smtp:\n";
}

Good luck.
PS: not tested in real environtment

  19 Responses to “Postfix Changing Outgoing IP By Time Interval Using TCP_TABLE And Perl”

Comments (19)
  1. Thank you.
    But I want to use SMTP with IP 184.172.219.242 (s22.vangxa1.com) & remove the main IP information 173.193.98.197 (s27.vangxa1.com). How to make it show the information 184.172.219.242 (s22.vangxa1.com) only?

  2. Hello

    I configured follow your instruction. Outgoing mail is ok. But incoming mail, I receive error: “mail for example.com loops back to myself”

    If I use “transport_maps = hash:/etc/postfix/transport” there is no error there.

    Can you fix it??

  3. there’s a quick workaround on comment section regarding “mail for example.com loops back to myself” error. example.com has to be in exception.

  4. example.com is just an example of mydomain.com.

    Our server use zpanel as control panel, I tried too many way but it still can’t receive mail.

    Please help me.

  5. as i said, you need to exclude your local/virtual domain in order not to get affected by the script. says, your domain is example.com and your maildir is virtual:

    while (<>) {
            chomp;
            my $time_stamp = retrieve($hashfile);
            my $now = time();
    
            if (!defined $time_stamp->{'time_diff'}) {
                    $time_stamp->{'time_diff'} = $now;
                    $time_stamp->{'ip_index'} = 0;
                    store $time_stamp, $hashfile;
            }
    
            if (/^get\s(.+)$/i) {
               my $local_domain = $1;
               $local_domain =~ s/.*\@//i;
               if ($local_domain eq "example.com") {
                    print "200 virtual:\n";
                    next;
               } else {
                    if ($now > $time_stamp->{'time_diff'} + $ip_interval) {
                            if ($time_stamp->{'ip_index'} < scalar(@smtp_array) - 1) {
                                    $time_stamp->{'ip_index'}++;
                            } else {
                                    $time_stamp->{'ip_index'} = 0;
                            }
                            print "200 $smtp_array[$time_stamp->{'ip_index'}]\n";
                            $time_stamp->{'time_diff'} = $now;
                            store $time_stamp, $hashfile;
                            next;
                    } else {
                            print "200 $smtp_array[$time_stamp->{'ip_index'}]\n";
                            next;
                    }
               }
            }
    
            ## default response 
            print "200 smtp:\n";
    }
    

    it’s not tested, but i hope you can figure it out

    cheer

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