iptables rules for p2p gtk-gnutella

slackbat · 04-08-2020, 05:14 AM

Hi all,

I am looking for an iptables rules - input/output tcp/udp - for gtk-gnutella.

No matter what I have tried it has not worked, and looking arong on the web has not come up with a solution.

Code:

# Following 2 rules 4 Gtk-Gnutella
$IPT -A INPUT -m state --state NEW,ESTABLISHED -p tcp --dport 40411 -j ACCEPT
$IPT -A INPUT -m state --state NEW,ESTABLISHED -p udp --dport 40411 -j ACCEPT
$IPT -A OUTPUT -m state --state ESTABLISHED -p tcp --dport 40411 -j ACCEPT
$IPT -A OUTPUT -m state --state ESTABLISHED -p udp --dport 40411 -j ACCEPT

Cant get this right - oh I'm using slackware - if that makes a difference.

TIA

jem777 · 04-23-2020, 07:56 AM

I'm not really familiar with gtk-gnutella, but with the above rules, your client will be able to receive connections, but not able to initiate connections of its own.

Also, please remember that iptables rules by default are for your *system*, not a particular piece of software you run.
A neat trick to apply rules to a particular piece of software only (though this can be done in more than one way), is to run that software under a particular user, and use iptables owner module:

iptables -A OUPUT -m owner --uid-owner <numeric id of the process owner> -j ACCEPT

A good way to debug is changing the rule that drops traffic to a log and drop. The below is from my firewall:

iptables -N LnD
iptables -A LnD -p tcp -m limit --limit 1/s -j LOG \
--log-prefix "[TCP DROP] " --log-level debug
iptables -A LnD -p udp -m limit --limit 1/s -j LOG \
--log-prefix "[UDP DROP] " --log-level debug
iptables -A LnD -p icmp -m limit --limit 1/s -j LOG \
--log-prefix "[ICMP DROP] " --log-level debug
iptables -A LnD -f -m limit --limit 1/s -j LOG \
--log-prefix "[FRAG DROP] " --log-level debug
iptables -A LnD -j DROP

And then just change the target of your rule(s) that drop traffic to -j LnD instead of -j DROP. That way, you can observe what gets dropped in your logfiles.

You can do something similar for accepted connections, though it has to be used cautiously on a system that has many accepted connections.

HTH.

slackbat · 04-24-2020, 02:53 AM

Hi jem777

Thanks for the reply and the valuable info. I will get to it, and report back (cant do it straight away).

Cheers