Hi all,

I have deployed iptables with mangle. Don't know why I can't ping even localhost after I mangle set-mark. Afterward, I have reset all rules (filter, nat, mangle) to ACCEPT. However, I still can't access the Internet, even the localhost. All I have to do is to stop iptables in order to access the Internet.

I am pretty sure the route setting is OK.

Does anyone please tell me what cause the problem? If it is some modules in mangle restricted all traffics (see the bottom bold and italic output). How could I unload the module if it is the cause?

[root@cen-vpn openvpn0]#ping localhost
PING cen-vpn (127.0.0.1) 56(84) bytes of data.
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted

[root@cen-vpn openvpn0]# service iptables stop
Flushing firewall rules: [ OK ]
Setting chains to policy ACCEPT: raw filter nat mangle [ OK ]
Unloading iptables modules: [ OK ]
[root@cen-vpn openvpn0]# service iptables start
Applying iptables firewall rules: [ OK ]
Loading additional iptables modules: ip_conntrack_netbios_n[ OK ]

Another Normal Computer with iptables:
[root@cen-cl ~]# service iptables stop
Flushing firewall rules: [ OK ]
Setting chains to policy ACCEPT: mangle nat filter [ OK ]
Unloading iptables modules: [ OK ]
[root@cen-cl ~]# service iptables start

Many Thanks,

While your rules are active, can you run the following (the first is if you're using NAT)? It will list out the rules in your NAT and filter tables: