iptables two network interfaces

[kiko]

I'm new in iptables so I need a little help.

I have the machine with next network card configuration:

eth0 - internal network, 10.x.x.x
eth1 - wan, static IP address

I executed the next iptable commands:

iptables -F
iptables -A INPUT -i eth1 -j REJECT

Everything is fine: the machine can not be "ping" by its static ip address over Internet and is fully reachable from the internal net.

but when I do ping from the machine: ping [some address on the internet] the address can not be reached.

but

iptables -F
ping [some address on the internet]

the address can be reached.

What did I do wrong?

 

[scorpio2k2]

hello kiko.

when you enter the iptables -A INPUT -i eth1 -j REJECT command you will reject all incoming packets on eth1 (here is included also the response from ping )


After you enter iptables -F, ping work because you are deleting all iptables rules.

--flush -F [chain] Delete all rules in chain or all chains

I hope this helps you

 

[kiko]

Scorpio2k2, Thanks for your answer.

How can I make the rule that will allow me to outgoing traffic but all incoming traffic from Internet to be rejected? That's really confusing me.

 

[Maverick1]

I think, you need to configure Ubuntu machine as a router.
Follow the guidelines given in following article:
http://www.yourownlinux.com/2013/07/how-to-configure-ubuntu-as-router.html

 

[Maverick1]

And as you said you are new to iptables, go through following tutorial as well. I felt it was handy for me.
http://www.yourownlinux.com/2013/05/iptables-linux-firewall.html

 

[Cristal Skull]

http://www.fwbuilder.org/

 

[nixsavy]

if you using static ip (internet) , block using ip as the source.
You just look for web blocking , try using port (80)

Good Luck