Help by defining rules in iptable

[alfer]

Hi friends!

I have a Linux system with the iptables installed. The system makes an IPMasqarading and filters traffic on external interface. The internal interface is mostly trusted.

Now I have to block a traffic from one computer (192.168.1.26) in internal network on one specific port (80). What shall I change in my ip-configuration? I have to block forwarding and accepting of port 80 for only this one computer (192.168.1.26)

I have following /etc/sysconfig/iptables file:
[tt]
# Firewall configuration written by lokkit
# Manual customization of this file is not recommended.
# Note: ifup-post will punch the current nameservers through the
# firewall; such entries will *not* be listed here.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Lokkit-0-50-INPUT - [0:0]
-A INPUT -j RH-Lokkit-0-50-INPUT
-A FORWARD -j RH-Lokkit-0-50-INPUT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 22 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 25 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 80 --syn -j ACCEPT
-A RH-Lokkit-0-50-INPUT -i lo -j ACCEPT
-A RH-Lokkit-0-50-INPUT -i eth0 -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 0:1023 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 2049 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 0:1023 -j REJECT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 2049 -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 6000:6009 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 7100 --syn -j REJECT
COMMIT[/tt]

I thought about a linie like:
[tt]-A RH-Lokkit-0-50-INPUT -p tcp -s 192.168.1.26 --dport 80 -j REJECT[/tt]
but this seems not working.

How would You change my configuration to perform my task?

Have I to restart the Linux or only /etc/init.d/iptables after such changes?

Thanks for any answer!

 

[BIS]

Since it's internal, I guess you are doing some sort of NAT. In that case put that rule on the FORWARD chain, not INPUT...

 

[marsd]

Firstly: To perform nat you must use the nat builtin and
one of its processing chains.
Secondly: To route traffic you must enable forwarding
and set up the proper rules in your Forward chain.

I would not use RH specific tools.
This is an example for network related activity and not
for INPUT rules affecting only your router.

iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT
iptables -t nat -A POSTROUTING -s $local_net -o $external -j MASQUERADE
iptables -A FORWARD -s $local_net -d 0/0 -o $external -j
ACCEPT
iptables -A FORWARD -s 0/0 -d $local_net -i $external --match state --state ESTABLISHED -j ACCEPT

Your rules as written are badly broken or insecure.
Check out Tony Mancill's "Linux Routers" which is
the best quality for your money when using linux as
a router IMHO.