I'll try to use Tie::File

use Tie::File;
#.......your code
#at this point you have
#@ports with port numbers
#and file address.txt which you need to append

tie @addresses, 'Tie::File', "address.txt" or die $!;
for my $position (0..$#ports) {
    $addresses[$position] .= $ports[$position];
}
untie @addresses;
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But you may combine reading of the ports file and updating addresses file (with $. magick).