cant ping fw

Jörg Harmuth harmuth at
Wed Jul 6 14:29:12 CEST 2005

Hi Brent,

Brent Clark schrieb:

> here is my OUTPUT
> $IPT -t filter -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
> $IPT -t filter -A OUTPUT -m state --state INVALID -j LOG --log-prefix
> "INVALID output: " --log-tcp-options --log-ip-options
> $IPT -t filter -A OUTPUT -m state --state INVALID -j DROP
> $IPT -t filter -A OUTPUT -m state --state NEW -j ACCEPT
> $IPT -t filter -A OUTPUT -j LOG --log-prefix "[OUTPUT DROP]: "
> --log-tcp-options --log-ip-options
> $IPT -t filter -A OUTPUT -j DROP
> and for my lo
> $IPT -A INPUT -i lo -j ACCEPT
> $IPT -A OUTPUT -o lo -j ACCEPT

Looking closer to your rules, I see these possibilities:

1.) For some reasons echo-request are considered INVALID. This should
    show up in your logs.
2.) You ping :)
3.) Your client doesn't find fw
4.) /proc/sys/net/ipv4/icmp_echo_ignore_all is set to 1

echo-replies are in state ESTABLISHED, so there is no problem with your
OUTPUT chain. I don't know the real reason, but I have a feeling, that
4.) is the best bet.

HTH and have nice time,


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