Linux Noob - Quick Nethwork Question

[bob4432]

on eth0, how can i limit what goes out on what port? is there some where that i can say something like on eth0 no tcp/upd from port x -> x?

thanks 🙂

 

[Crusty]

Unfortunately in a noob when it comes to Linux networking 😉. I know how to get a connection up and running 😛, but that's about it.

I could be wrong..but I think iptables are what you are looking for. I'll poke around on google and see what I can find out.

 

[n0cmonkey]

iptables (netfilter.samba.org?) is definitely what you are looking for. If I had ever set it up, I'd drop a few more hints. 😛

 

[Nothinman]

http://netfilter.org/documentation/HOWTO//packet-filtering-HOWTO-7.html

 

[drag]

Also if you use Fedora you have a iptables firewall setup as default.

To get to the configuration tool you go thru the application menu --> System Settings --> Security Level to mess around with it. It's very simple/limited, open some ports, the rest are closed by default, I have SSH open on my laptop by default, but most of the time I just turn it completely off when I am on my home lan.

There are bunches of tools and howtos to do more sophisticated setups. Port forwarding, routing, setting up DMZ zones, setting up encrypted tunnels (vpn's) and whatever you want. Sky is the limit.

Google helps out a lot in this situation.

 

[bob4432]

Originally posted by: drag
Also if you use Fedora you have a iptables firewall setup as default.

To get to the configuration tool you go thru the application menu --> System Settings --> Security Level to mess around with it. It's very simple/limited, open some ports, the rest are closed by default, I have SSH open on my laptop by default, but most of the time I just turn it completely off when I am on my home lan.

There are bunches of tools and howtos to do more sophisticated setups. Port forwarding, routing, setting up DMZ zones, setting up encrypted tunnels (vpn's) and whatever you want. Sky is the limit.

Google helps out a lot in this situation.

thanks for all the info, very helpfu.

i am using fedora 2 so i will check into that. i didn't have it install the firewall because since i don't really know what i am doing in linux, i didn't want to be dealing with that also. i will look into it.

 

[drag]

you may already have it installed. Check out your runlevel configurations. Application menu --> System settings --> server settings.

From their you can turn on and turn off various services you have aviable. See if you can find one that is labled "iptables", that will also show your firewall configuration if you have one. (also while your there, turn off ones you don't need. And turn on "readahead", "readahead_early". They claim to make your boot up times quicker.)

Runlevels are different system states. You have a runlevel for shutdown, and one for reboot. Runlevel 5 is default, and that is "multiuser with X", and I have it run at runlevel 3 which means "multiuser without X". So that way you can (if for instance your installing nvidia drivers and need to turn off X) go "telinit 3" (at a command line as root or su) to turn X off completeley, and "telinit 5" to get back into a graphical login.

Otherwise you have stuff like "firewall builder" (fwbuilder), Gnome Firestarter configuration tool, or Shorewall (popular) firewall tools to make very custom setups. The default firewall is very basic. Other then that you can just setup iptables by hand and a lot of people do that.