Here's one way to easily store and edit the numbers. You could also store them in a separate file, but I like the DATA trick better. Either way, the list can easily be maintained by others who may not know about regexp or perl code:

#!/bin/nsperl

use strict;

my $trojanfile = "trojan.log"; ## At the top makes it easier to find i
+f it is changed

## Read in all the port numbers
my %number;
while(<DATA>) {
  /^#/ and next;             ## Skip lines starting with '#'
  /(\d+)/ and $number{$1}++; ## Hash eliminates doubles gracefully
}
my $findport;
for (sort {$a <=> $b} keys %number) { ## Sort makes it easier to read
  $findport .= "$_|";
}
chop $findport;              ## Yes, this is chop, not chomp!

open (FILEOUT, ">$trojanfile") or die "Can't open $trojanfile: $!\n";
print FILEOUT "Searched for: $findport\n";

## Slow but succinct:
(my $logfile=`date +%d%b%Y` . ".elog") =~ s/\n//;

open (FWLOG, "$logfile") or die "Can't open $logfile: $!\n";
while(<FWLOG>){
  print FILEOUT if (/\b(?:$findport)\b/o); ## nice call ferrency
}
close(FWLOG);
exit;

__DATA__

## This is the list of ports
## Lines with a '#" at the start are comments
## Everything else is a port number to check for
## Even embedded comments are okay, just have the number go first
12345
12346
31337 ## Default back orifice port
 8787 ## Other comments here
                1823 This is a comment too, but without the nice '#'
88776
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