From: Patrick McHardy <kaber@trash.net>
To: "John A. Sullivan III" <jsullivan@opensourcedevel.com>
Cc: netfilter-devel@lists.netfilter.org
Subject: Re: NetBIOS datagram nat helper proposal
Date: Wed, 21 Sep 2005 00:51:35 +0200 [thread overview]
Message-ID: <43309277.2040900@trash.net> (raw)
In-Reply-To: <1127181124.29021.34.camel@localhost>
John A. Sullivan III wrote:
> On Tue, 2005-09-20 at 02:32 +0200, Patrick McHardy wrote:
>
>>>We are seeing if we have the resources to finish and polish this patch
>>>and submit it. It seems that we then simply post it to this list to
>>>submit it. Is that the correct procedure?
>>
>>Yes, if the patch is OK conceptually. If you send me some pointers,
>>I'll have a look.
>>
>
> I believe it is defined by RFC1002. You can find it here:
> http://ubiqx.org/cifs/rfc-draft/rfc1002.html#s4.4
> I would think it is pretty straightforward but it is so easy to
> dreadfully underestimate these things. Thanks - John
Thanks. Looking at the RFC, the patch is incomplete in at least two
ways. First, the protocol includes broadcasts, these need to be tracked
in a similar way to ip_conntrack_netbios_ns. Second, the helper only
NATs the source IP but the packets also include the source port, it
needs to be translated as well. I'm not sure how the reply packets
look, I found some broadcast queries in my local network, but don't
have access to any of the machines to sniff the unicast replies.
# tcpdump -i eth0 -ntv port 138
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 96
bytes
IP (tos 0x0, ttl 128, id 64557, offset 0, flags [none], proto: UDP (17),
length: 229) 172.16.0.77.138 > 172.16.255.255.138: NBT UDP PACKET(138)
IP (tos 0x0, ttl 128, id 52744, offset 0, flags [none], proto: UDP (17),
length: 239) 172.16.1.56.138 > 172.16.255.255.138: NBT UDP PACKET(138)
IP (tos 0x0, ttl 128, id 37133, offset 0, flags [none], proto: UDP (17),
length: 229) 172.16.1.11.138 > 172.16.255.255.138: NBT UDP PACKET(138)
IP (tos 0x0, ttl 128, id 53239, offset 0, flags [none], proto: UDP (17),
length: 229) 172.16.1.56.138 > 172.16.255.255.138: NBT UDP PACKET(138)
If you can provide me with some packet dumps of a machine sending and
receiving these packets I'll give it a try, it shouldn't be much work.
prev parent reply other threads:[~2005-09-20 22:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-19 21:10 NetBIOS datagram nat helper proposal John A. Sullivan III
2005-09-19 21:27 ` Phil Oester
2005-09-19 21:30 ` Krzysztof Oledzki
2005-09-19 21:39 ` John A. Sullivan III
2005-09-20 0:32 ` Patrick McHardy
2005-09-20 1:52 ` John A. Sullivan III
2005-09-20 8:56 ` IPT_RETURN is not worked in the kernel 2.6.10 Vincent
2005-09-20 22:51 ` Patrick McHardy [this message]
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