Thanks Brian, Excellent suggestion! This is where I am so far:

#!/usr/bin/perl -w
use strict;
use Net::Pcap;
use NetPacket::Ethernet;
use NetPacket::IP;
use NetPacket::TCP;

my $err;
my $dev = $ARGV[0];
my $object;

$object = Net::Pcap::open_offline($dev, \$err);
unless (defined $object) {
    die 'Unable to create packet capture on device ', $dev, ' - ', $er
+r;
}


Net::Pcap::loop($object, -1, \&callback_function, '');
Net::Pcap::close($object);

sub callback_function {
  my ($user_data,$header,$packet) =@_;
  my $ether_data = NetPacket::Ethernet::strip($packet);
  my $ip = NetPacket::IP->decode($ether_data);
  my $tcp = NetPacket::TCP->decode($ip->{'data'});
  print
    $ip->{'src_ip'}, ":", $tcp->{'src_port'}, " -> ",
    $ip->{'dest_ip'}, ":", $tcp->{'dest_port'}, "\n";
}
[download]

With errors as

Use of uninitialized value in unpack at /usr/lib/perl5/site_perl/5.8.0
+/NetPacket/TCP.pm line 138.
57.24.4.3:260 -> 0.0.100.0:33412
178.163.14.0:29300 -> 0.0.100.0:29295
3.0.0.0:0 -> 8.0.69.0:16401
252.87.141.0:4356 -> 0.0.100.0:12
Use of uninitialized value in unpack at /usr/lib/perl5/site_perl/5.8.0
+/NetPacket/TCP.pm line 138.
157.24.4.3:260 -> 0.0.100.0:33412
253.87.141.0:4356 -> 0.0.100.0:12
Use of uninitialized value in unpack at /usr/lib/perl5/site_perl/5.8.0
+/NetPacket/TCP.pm line 138.
159.24.4.3:260 -> 0.0.100.0:33412
239.36.90.0:0 -> 0.0.100.0:5
240.36.90.0:0 -> 0.0.100.0:5
3.37.90.0:0 -> 0.0.100.0:5
5.37.90.0:0 -> 0.0.100.0:5
3.0.0.0:1 -> 8.6.0.1:2560
[download]

I bet all I need to do now is either find or write an appropriate NetPacket module. Almost there!