Re: iptables icmp protocol match bug.

[Patrick McHardy <kaber@trash.net>]

Peteris Krumins wrote:

>Hello,
>
> A quick bug report:
>
> iptables -A INPUT -p icmp --icmp-type 255 -i lo -j REJECT
>

This is deliberate. There is no valid icmp-type 255, it is used as a
wildcard to match every possible type. See icmp_type_code_match()
in ip_tables.c. Perhaps the userspace tool should warn about invalid
types ?

Patrick

>
> this rule also denies icmp ping and i think anything else of icmp.
>
> Works for me at least on 2.4.22-pre6 and patch-o-matic-20030714
> havent tried w/ newer versions.
> 
> Does not work on base 2.4.20 and iptables 1.2.7a
>
>proof:
>--
>z@xor:/[1032]# iptables -A INPUT -p icmp --icmp-type 255 -i lo -j REJECT
>z@xor:/[1033]# ping localhost -c 5
>PING localhost (127.0.0.1): 56 octets data
>
>--- localhost ping statistics ---
>5 packets transmitted, 0 packets received, 100% packet loss
>
>z@xor:/[1034]# iptables -D INPUT -p icmp --icmp-type 255 -i lo -j REJECT
>z@xor:/[1035]# ping localhost -c 5
>PING localhost (127.0.0.1): 56 octets data
>64 octets from 127.0.0.1: icmp_seq=0 ttl=128 time=0.3 ms
>64 octets from 127.0.0.1: icmp_seq=1 ttl=128 time=0.3 ms
>^C
>
>
>P.Krumins
>
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>netfilter-devel@lists.netfilter.org
>  
>