allowing gif thru ipfw

[Kirk Davis]

On Wednesday, February 01, 2012 7:24 AM  wrote Eugene Grosbein
>01.02.2012 21:12, Eric W. Bates пишет:
>> On 2/1/2012 3:06 AM, Doug Barton wrote:
>>> If it's a hurricane electric tunnel don't you want protocol 41?
>> 
>> Well, it's a straight up gif. Right this second I'm trying to suss out 
>> which protocol gif's use. If it's documented, I can't find it. The 
>> closest bit I can find on the man page is:
>> 
>> The behavior of gif is mainly based on RFC2893 IPv6-over-IPv4 
>> configured tunnel.
>> 
>> I tried to read the pertinent parts of the RFC, but it doesn't really 
>> discuss "type" or "protocol". It does talk about some header size issues.
>> 
>> Since ipfw is obviously blocking something and I can't get a handle on 
>> it with tcpdump, I'm groping for an understanding of the shape of the 
>> gif packets.
>
>Have you tried "tcpdump -i em_vlan5 -nnvvs0 host $he_tun and not tcp and not udp and not icmp" ?
>
>I do not use IPv6 over IPv4 tunnels and not sure.
>Perhaps, that is IPIP protocol (number 94 decimal)?

I use a number of gif tunnels with ipfw and I have always used 'ipencap' (protocol 4) for my ipfw rules. One you break it out of the tunnel though you can then use ipfw one the inside tunnel traffic.  I don't have one with HE right now so they may be different but this is what I use for a standard ipv4-ipv4 gif tunnel.

---- kirk