Here you go, shows everything is as it should be :)

#!/usr/bin/perl --

use strict;
use warnings;

use IO::Socket;

my $sock = IO::Socket::INET->new (
    Localhost => 'localhost',
    LocalPort => '18080',
    Proto => 'tcp',
    Listen => 1,
);
die "cant do that: $!\n" unless $sock;

print "Please contact me at: http://localhost:18080\n";

my $CRLF = "\015\012";
while(my $s = $sock->accept()){
    
    while(<$s>){
        print $s "Echo: $_";
        last if /^\s+$/;
    }
    close $s;
}
close $sock;


__END__
$ lwp-request http://localhost:18080

Echo: GET / HTTP/1.1
Echo: TE: deflate,gzip;q=0.3
Echo: Connection: TE, close
Echo: Host: localhost:18080
Echo: User-Agent: lwp-request/2.06
Echo:
[download]