randomize – KutuKupret

Postfix Changing Outgoing IP By Time Interval Using TCP_TABLE And Perl

email, linux, modules, perl, pop3, postfix, programming, sendmail, smtp 14 Responses »

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

Postfix Rotating Outgoing IP Using TCP_TABLE And Perl

email, load balance, modules, postfix, smtp 5 Responses »

May 222011

In The last article “Postfix Randomizing Outgoing IP Using TCP_TABLE And Perl“, i was writing about my experiment randomizing outbound ip. someone asked if the script can be mimicked as in the iptables statistic module. indeed, when using the previous script, the results obtained will really random. although that is what the script was created.

I found this wiki explaining about Weighted Round-Robin Scheduling.

Supposing that there is a server set S = {S0, S1, …, Sn-1};
W(Si) indicates the weight of Si;
i indicates the server selected last time, and i is initialized with -1;
cw is the current weight in scheduling, and cw is initialized with zero;
max(S) is the maximum weight of all the servers in S;
gcd(S) is the greatest common divisor of all server weights in S;

while (true) {
    i = (i + 1) mod n;
    if (i == 0) {
        cw = cw - gcd(S);
        if (cw <= 0) {
            cw = max(S);
            if (cw == 0)
            return NULL;
        }
    }
    if (W(Si) >= cw)
        return Si;
}

anyway, I do not have much time to implement that algorithm into the script, so I use an existing perl module List:: util:: WeightedRoundRobin
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