use IO::Socket;

my $server = IO::Socket::INET->new(
    Listen => 5,
    LocalAddr => 'localhost',
    LocalPort => 5050,
    Proto     => 'tcp'
) or die "Can't create server socket: $!";

my $client = $server->accept;

open FILE, ">out" or die "Can't open: $!";
while (<$client>) {
    print FILE $_;
}
close FILE;

##</code><code>##

use IO::Socket;

my $server = IO::Socket::INET->new(
    PeerAddr => 'localhost',
    PeerPort => 5050,
    Proto    => 'tcp'
) or die "Can't create client socket: $!";

open FILE, "in";
while (<FILE>) {
    print $server $_;
}
close FILE;