Hello monks.

I recently started using the TPROXY (transparent proxy) kernel extensions that make it possible to bind to non-local IP address in Linux kernel 2.6.

A recent kernel with TPROXY support is in use and netfilter/iptables has been re-compiled with TPROXY support.
Do I need to recompile Perl as well?

In the following code, setting the IP address literal on line 16 to my local IP address works. But using a non-local address causes the connect on line 22 to die with the error:

connect: Invalid argument at test line 22. 
#!/usr/bin/perl

use strict;
use Socket qw(:all);

use constant SOL_IP => 0;
use constant IP_FREEBIND => 15;

$|++; # no buffering

my $proto = getprotobyname('tcp');
socket(Socket_Handle, PF_INET, SOCK_STREAM, $proto) or die "socket: $!
+";
setsockopt( Socket_Handle, SOL_IP, IP_FREEBIND, 1) or die "setsockopt:
+ $!";

# set local address to a non-local address :)
my $laddr = inet_aton('10.8.31.5');
bind(Socket_Handle, sockaddr_in(0,$laddr)) or die "bind: $!";

# attempt to connect to remote webserver
my $port = getservbyname('http', 'tcp');
my $sin = sockaddr_in($port,inet_aton("www.google.com"));
connect(Socket_Handle,$sin) or die "connect: $!";;

sleep 2;
close (Socket_Handle)            || die "close: $!";
exit;

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In reply to How do I enable TPROXY in Perl? by charlesboyo

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