Re: [squid-users] iptables stops pingning (with iptables file)

Seems I got bored and looked at your problem anyway ...

Yogesh Patil wrote:
> * Sorry for dulipcate messages, i don't know that it doesn;'t supports
> big attachment
>
> Hello,
> I am using SQUID 2.6.STABLE17 with fedora core 8, & BIND
> DNS SERVER configured on the same box, i have configured squid as
> transparent proxy, and applied iptables rule by using the following
> command
>
> iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT
> --to-port 3128
>
> service iptables save
>
> so when i restart iptables after appling & saving above i
> get following:
>
> Flushing firewall rules: [ OK ]
> Setting chains to policy ACCEPT: filter nat [ OK ]
> Unloading iptables modules: [FAILED]
> Applying iptables firewall rules: [ OK ]
> Loading additional iptables modules: nf_conntrack_netbios_n[ OK ]
>
> so if i try to ping to (any public ip) from client PC after
> enabling iptables i get request time out, but i can browse websites
> without any problem, and if i disable iptables i can get reply from
>
> the (public ip) to which i am pinging and browsing also works. also
> checked DNS resolution it works perfectly as browsing works.
>
> so i would like to know what is the reason of stopping ping
> after enabling iptables and why i am getting Unloading iptables
> modules FAILED.
>
> HERE IS MY /etc/iptables FILE
> # Generated by iptables-save v1.3.8 on Sat Jan 26 17:51:31 2008
> *nat
> :PREROUTING ACCEPT [5:862]
> :POSTROUTING ACCEPT [0:0]
> :OUTPUT ACCEPT [0:0]
> -A PREROUTING -i eth0 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 3128
> COMMIT
> # Completed on Sat Jan 26 17:51:31 2008
> # Generated by iptables-save v1.3.8 on Sat Jan 26 17:51:31 2008
> *filter
> :INPUT ACCEPT [0:0]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [5:454]
> :RH-Firewall-1-INPUT - [0:0]
> -A INPUT -j RH-Firewall-1-INPUT
> -A FORWARD -j REJECT --reject-with icmp-host-prohibited
> -A RH-Firewall-1-INPUT -i lo -j ACCEPT
> -A RH-Firewall-1-INPUT -i eth0 -j ACCEPT
> -A RH-Firewall-1-INPUT -p icmp -m icmp --icmp-type any -j ACCEPT

This ICMP ACCEPT is in INPUT chain.
FORWARD chain contains only a global REJECT which will aturally block
ICMP, UDP, TCP and everythign else being forwarded.

Transparent-Squid only works because www packets now secretly going to
localhost via INPUT and OUTPUT without entering FORWARD chain.

Try adding:
-A FORWARD -p icmp -m icmp --icmp-type any -j ACCEPT

ahead of the first "-A FORWARD" line.
Or reconsidering your FORWARD content entirely.

> -A RH-Firewall-1-INPUT -p esp -j ACCEPT
> -A RH-Firewall-1-INPUT -p ah -j ACCEPT
> -A RH-Firewall-1-INPUT -d 224.0.0.251 -p udp -m udp --dport 5353 -j ACCEPT
> -A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT
> -A RH-Firewall-1-INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
> -A RH-Firewall-1-INPUT -p udp -m state --state NEW -m udp --dport 137 -j ACCEPT
> -A RH-Firewall-1-INPUT -p udp -m state --state NEW -m udp --dport 138 -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 139 -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 445 -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 53 -j ACCEPT
> -A RH-Firewall-1-INPUT -p udp -m state --state NEW -m udp --dport 53 -j ACCEPT
> -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 3128
> -j ACCEPT
> -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
> COMMIT
> # Completed on Sat Jan 26 17:51:31 2008
>
>
>
>
> THANKS IN ADVANCE
>
>
>
> --
> Regards,
> Yogesh Patil

-- 
Please use Squid 2.6STABLE17+ or 3.0STABLE1+
There are serious security advisories out on all earlier releases.