Re: minimal iptables ruleset for laptop

[Georgi Alexandrov <tehlists@xxxxxxxxxx>]

Volkm@r wrote:

> Sorry for this newbie question - I'm just learning about iptables.
>
> What I have is a laptop that I want to protect against external
> intrusion. Relevant interfaces are
>
> - eth0, which is LAN and sometimes DHCP sometimes pppoe
> - eth1, which is WLAN and sometimes behind my private AP
>        and sometimes behind company's or public APs
>
> Of course, this laptop would never have to act as a router.
> I want to prevent any external intrusion but be able to connect myself
> to any external service. AND I want to be able to run some services
> (X11, CUPS, Tomcat,...) just for myself.
>
> > From somewhere on the internet I got the following snippet which I think
> may be suitable for ppp0 as the only interface. But I couldn't find out
> how to change it for my needs.
>
> -------------------------------------------------------------------------
> # Generated by iptables-save v1.2.11 on Mon May 23 15:54:20 2005
> *filter
> :INPUT ACCEPT [10502:1065067]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [1529512:141800679]
> :block - [0:0]
> -A INPUT -j block
> -A FORWARD -j block
> -A block -m state --state RELATED,ESTABLISHED -j ACCEPT
> -A block -i ! ppp0 -m state --state NEW -j ACCEPT
> -A block -j DROP
> COMMIT
> # Completed on Mon May 23 15:54:20 2005
> -------------------------------------------------------------------------
>
> Any help will be much appreciated.
>  
something like this:

######################### start ###########################

iptables -F
iptables -X
iptables -Z
iptables -t nat -F
iptables -t nat -X
iptables -t nat -Z
iptables -t mangle -F
iptables -t mangle -X
iptables -t mangle -Z

iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 3 -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 11 -j ACCEPT
iptables -A INPUT -p icmp --icmp-type 12 -j ACCEPT
iptables -A INPUT -p tcp --syn --dport 113 -j REJECT --reject-with tcp-reset

############################# end #################################

I think the above ruleset is sufficient. If you have any questions about 
it - just ask.

regards,
Georgi Alexandrov