[Firehol-support] DROPping INVALID in OUTPUT

Mark Hindley mark at hindley.uklinux.net
Thu Jun 3 10:55:37 BST 2004

First of all, many thanks for Firehol. It has really simplified use of

I have one problem, however. 
Using eth0 LAN, ppp0 dial-up link. Masquerade, using lan-gateway.conf as template for config.

If the ppp link is down and a host on the LAN sends a packet destined
for the outside world, the icmp-unreacahble packet does not get
returned, so the LAN host has to wait to time out.

The offending line seems to be: 

${IPTABLES_CMD} -A OUTPUT -m state --state INVALID -j DROP

Although the comment says this is recommended in the Netfilter HOWTO, I
cannot find it.

I can fix it by adding 

iptables -I OUTPUT 2  -m state --state INVALID -p icmp --icmp-type  destination-unreachable -j ACCEPT

Is this sensible? But surely these packets  are not really INVALID. Are
the not RELATED. Is this a iptables bug, or something that should be
accommodated in Firehol?

Thanks for your help

Mark Hindley

6, Nursery Park

01896 830304

mark at hindley.uklinux.net

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