AW: [Asterisk-Users] Snom 200 with two extns defined anyone?

[Christian Stredicke]

We at snom have problems with Asterisk when we receive calls without the
line indication. When we register we place a contact like this:

REGISTER sip:asterisk SIP/2.0
Contact: <sip:123 at 192.168.0.99;line=h35h345>

When we receive the 200 Ok, we search for the "h35h345". If we don’t find
it, we try to guess which line is affected. This is relatively easy on a
REGISTER response, but on an incoming INVITE we have serious problems. I
think some of the challenging and line-assignment problems are related to
this problem.

Strictly speaking, we register the contact
"sip:123 at 192.168.0.99;line=h35h345", NOT "sip:123 at 192.168.0.99"! Parameters
are an essential part of a URI which must not be discarded.

BTW the line-id has also the function of increasing the security
significantly. Just imaging a network script that sprays INVITE packets
through the network - the whole office would start ringing.

#!/bin/bash
# Give the colleagues a wake-up call!
i=1
while [ $i -lt 256 ]; do
  echo INVITE sip:192.168.0.$i SIP/2.0^M >junk.txt
  echo f: sip:whoever at is.stupid^M >>junk.txt
  echo t: sip:enough at to.accept^M >>junk.txt
  echo i: this at junk^M >>junk.txt
  echo l: 0^M >>junk.txt
  echo CSeq: 1 INVITE^M >>junk.txt
  echo ^M
>>junk.txt
  cat junk.txt >/dev/udp/192.168.0.$i/5060
  i=$[$i+1]
done

Unfortunately, the snom phones are not able to pick the right line on these
packets!

By requiring the line id, the phone would reject the INVITE as it can not
match the request URI with any valid line on the phone! BTW that’s why I
hate "direct IP calls" - it gives you zero security against such attacks.

Our latest image is 2.03e (http://snom.com/download/share), it does strict
line id comparison and tries to deal with "junk" line identifications as
good as possible. 


Happy New Year! Christian

> -----Ursprüngliche Nachricht-----
> Von: asterisk-users-admin at lists.digium.com [mailto:asterisk-users-
> admin at lists.digium.com] Im Auftrag von Rich Adamson
> Gesendet: Donnerstag, 1. Januar 2004 00:26
> An: Asterisk-a-users-list
> Betreff: [Asterisk-Users] Snom 200 with two extns defined anyone?
> 
> 
> Are there any Snom 200 users that have two extns defined on their phone?
> 
> I've been trying to get two (or more) extns defined in such a way that
> when extn #1 rings, LED #1 flashs; extn #2 rings, LED #2 flashes, etc.
> (Answer greating will be different depending upon which extension is
> called.)
> 
> I can get multiple extns to register and work with * just fine, but
> regardless of which extn is called, only the Line 1 key flashes. I'm
> tried both v2.02t and v2.03e code with same result.
> 
> As soon as I define Key Mappings for P1 and P2, the phone goes into
> a constant Register, 100 Trying, 407 Proxy Authentication Required loop
> that never ends. 1,000's of packets spewing in the loop.
> 
> Thoughts?
> 
> Rich
> 
> 
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