perl_nc.pl

#!/usr/bin/perl 

use strict;
use IO::Socket;
use IO::Select;
use Getopt::Std; 

my %option;getopts('lp:', %option); 
# listen on local port

if( defined $option{'l'} )
{    
    if( !defined $option{'p'} )    
    {        
        &Usage( );
        exit( -1 );    
    }
    my $port = $option{'p'};
    my $listen = IO::Socket::INET->new(Proto => 'tcp',
    LocalPort => $port,
    Listen => 1,
    Reuse => 1) or die "Listen on port $port error: $!n";

    while( my $client_sock = $listen->accept() )
    {
        &ProcessData( $client_sock );
    }
} 

# if has no -l argument, maybe want to connect to other host
if( @ARGV != 2 )
{
    &Usage( );
    exit( -1 );
}

my $client_sock = IO::Socket::INET->new(Proto => 'tcp',
 PeerHost => $ARGV[0],
 PeerPort => $ARGV[1] ) || die "Connect to $ARGV[0]:$ARGV[1] error:$!n";
 &ProcessData( $client_sock );

 sub ProcessData
 {
    my $client_sock = shift;
    my $select = IO::Select->new( );
    $select->add( *STDIN );
    $select->add( $client_sock );

    my $buffer;
    while( 1 )
    {
        if( ! $select->exists( $client_sock ) )
        {
            print "waiting connection....n";
            last;
        }

        my @ready = $select->can_read;

        for my $tmp_sock(@ready)
        {
            if( $tmp_sock eq *STDIN )
            {
                if( my $recv_len = sysread( *STDIN, $buffer, 1024 )  )
                {
                    if( ! syswrite($client_sock, $buffer) )
                    {
                        $select->remove( $client_sock );
                        $select->remove( *STDIN );
                        close( $client_sock );

                        last;
                    }
                }
                else
                {
                    $select->remove( $client_sock );
                    $select->remove( *STDIN );
                    close( $client_sock );

                    last;
                }
            }

            elsif( $tmp_sock eq $client_sock )
            {
                if( my $recv_len = sysread( $client_sock, $buffer, 1024*5 ) )
                {
                    if( ! syswrite( *STDOUT, $buffer) )
                    {
                        $select->remove( $client_sock );
                        $select->remove( *STDIN );


                        close( $client_sock );

                        last;
                    }
                }
                else
                {
                    print "socket disconnected.n";
                    $select->remove( $client_sock );
                    $select->remove( *STDIN );
                    close( $client_sock );

                    last;
                }
            }
        }
    }
}

 sub Usage
 {
    print "simple nc.pl, code by wustyunshu@hotmail.comn";
    print "this script don't support -e cmd.exe, ^_^n";
    print "Usage:n";
    print "t  -l -p 99n";
    print "t 192.168.0.1 80n";
}