Try this:

use warnings;
use strict;
use Net::IPAddr;

open(file_info,$file) or die "Can't open $file ";
my @records;
while (<file_info>) {
  my ( $src_ip, $src_port ) = /IP\s+(\d+(?:\.\d+){3})\.(\d+)/;
  my ( $dst_ip, $dst_port ) = />\s+(\d+(?:\.\d+){3})\.(\d+)/;
  push @records, [$src_ip , $src_port , $dst_ip , $dst_port];
}
close(file_info);

my %seen;
my @result = 
  map { $_->[5] }  
  sort {           
      $a->[0] != $b->[0] ? $a->[0] <=> $b->[0]
    : $a->[1] != $b->[1] ? $a->[1] <=> $b->[1]
    : $a->[2] != $b->[2] ? $a->[2] <=> $b->[2]
    : $a->[3] <=> $b->[3]
  } 
  map { $seen{$_->[4]}++ ? () : $_ } 
  map { [ip2num($_->[0]), $_->[1], ip2num($_->[2]), $_->[3], join(',',
+@$_), $_ ]  } 
    @records;

print join(' ',@$_)."\n" for @results;
[download]

[4] is the stringified record for efficient existence tests.

[5] is the original record format for better re-use.

-David

Updated: made this node more stand-alone.