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To: "CIPE-list" <cipe-l,AT,inka,DOT,de>
Subject: Re: tcpdump - laptop
From: "Hans Steegers" <hsx,AT,dds,DOT,nl>
Date: Thu, 11 Sep 2003 22:25:16 +0200
Reply-to: "Hans Steegers" <steegers,AT,steegers,DOT,nl>

James,
I'll give it another (last!) try:

What all those packet dumps tell me is this:

1. there was no file transfer at all: all dumps contained only small
(protocol) packets. conclusion: the SAMBA server didn't even try to transfer
a file.

2. For a 'failing PMTU discovery' problem, we should have seen at least 1
large packet. Since there are none we have to look further.

3. The cipe interface 192.168.2.20 on the notebook informed the server
92.168.1.10 that port 138/udp is (blocked or not listening:) unreachable,
after receiving an NBT UDP PACKET(138) from the server. We can follow the
NBT packet from server to notebook and the ICMP answer from notebook to
server. So the server stopped. What tell the Samba logs?

** Find the reason why cipe cannot pass on port 138/udp packets to the lo
interface on the notebook:

-> Check with 'netstat -lun' on the notebook if listening on ports 137 and
138.
you should see something like:
..
udp        0      0 192.168.2.20:137        0.0.0.0:*
udp        0      0 0.0.0.0:137             0.0.0.0:*
udp        0      0 192.168.2.20:138        0.0.0.0:*
udp        0      0 0.0.0.0:138             0.0.0.0:*
..

-> Or, there MUST be an overlooked difference between the set-ups for
connecting via LAN, Wireless or modem, and your notebook firewall IS
blocking 138/udp traffic between lo and cipcb0 (only) for the modem setup.
All traffic between lo and cipcb0 must be allowed.

These are -AFAIK (with the info supplied)- the only two possible reasons
causing the 'port 138/udp unreachable' reply packets.

Hans Steegers

-----Original Message-----
From: James Knott <james.knott,AT,rogers,DOT,com>
To: CIPE <cipe-l,AT,inka,DOT,de>
Date: Thursday, September 11, 2003 6:30 PM
Subject: tcpdump - laptop_cipb0 IP 192.168.2.20

>21:41:30.530164 192.168.1.10.netbios-dgm > 192.168.2.20.netbios-dgm:
> >>> NBT UDP PACKET(138) Res=0x110A ID=0x70F9 IP=192 (0xc0).168 (0xa8).1
>(0x1).10 (0xa) Port=138 (0x8a) Length=213 (0xd5) Res2=0x0
>SourceName=LINUX           NameType=0x00 (Workstation)
>DestName=
>WARNING: Short packet. Try increasing the snap length
>
>  (DF) (ttl 63, id 0, len 241)
>21:41:30.530216 192.168.2.20 > 192.168.1.10: icmp: 192.168.2.20 udp port
>netbios-dgm unreachable [tos 0xc0]  (ttl 255, id 55713, len 269)
>21:42:32.070193 192.168.1.10.netbios-ssn > 192.168.2.20.32775: F [tcp
>sum ok] 83:83(0) ack 245 win 6432 <nop,nop,timestamp 26704482 123703>
>(DF) (ttl 63, id 1981, len 52)
>21:42:32.110039 192.168.2.20.32775 > 192.168.1.10.netbios-ssn: . [tcp
>sum ok] ack 84 win 5608 <nop,nop,timestamp 135719 26704482> (DF) (ttl
>64, id 36155, len 52)
>
>
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