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Re: iptables stops pingning (with iptables file)

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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.

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