[SIP Beyond VoIP] SylkServer not forwarding XMPP messages to SIP Proxy

David Hubbard david.hubbard at agenor.co.uk
Thu Oct 3 15:36:14 CEST 2013


I have now resolved this - but a couple of things arise.

Firstly in terms of resolution the "domains" within "xmppgateway.ini" 
needed to include my target domain name (myexternal.com) even though 
this isn't an XMPP domain (it's SIP)

    domains = myinternal.com,myexternal.com

I don't know if this is intended - the text says "Comma-separated list 
of Internet domains for which this server is responsible" - is 
SylkServer 'responsible' for all the domains that source XMPP users 
might connect to? - in my scenario (XMPP internal and SIP external via 
SIP Gateway) I was figuring that it was the SIP Gateway that was dealing 
with the external domains.

As it stands this list would need to include all the SIP domains that 
the source XMPP users might want to connect to - is that correct?  I can 
see that it might be useful to be able to force validation of source and 
target domains (from a lock-down point of view), but should these be an 
optional configuration items defaulting to false?.

After a deal of deep tracing I've found that this error is being raised 
deep with the wokkel code (base XMPP Server code).

    In XMPPServerListenAuthenticator.onVerify
            originatingServer = jid.JID(verify['to']).host

             if originatingServer not in self.service.domains:
                 raise error.StreamError('host-unknown')

Following that I've then found that host entry in the "outbound_gateway" 
can be an IP address (as my original) but not an internal domain name, 
while it can be an external domain name. With the internal domain name I 

    [xmppgateway] DNS lookup error while looking for
    sip:sipgateway.myinternal.com:5060;transport=udp proxy

As my SIP Gateway is an internally hosted box I was expecting that it 
would use the local machine domain name server and not those of my 
default gateway.  This is similar to a question I posed on Blink forum - 
as client appears to do the same.

 From dig - which is what the linux server view of DNS

    [root at agn10 sylkserver]# dig sipgateway.myinternal.com

    ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.6 <<>>
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55144
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

    ;sipgateway.myinternal.com.          IN      A

    *sipgateway.myinternal.com.   0       IN      A*

    ;; Query time: 2 msec
    ;; SERVER:
    ;; WHEN: Wed Oct  2 14:05:01 2013
    ;; MSG SIZE  rcvd: 54


On 01/10/2013 13:16, David Hubbard wrote:
> Hi
> I'm (now) getting an error sending a contact request from an XMPP 
> Server through SylkServer and onto OpenSIPS Server.
> SylkServer sends a "host-unknown" back to XMPP server - shown in 
> xmpp_trace.txt (below)
> I have outbound_proxy set in "config.ini" as:
>     outbound_proxy =;transport=udp
> and I am able to connect into this port (using nc)  - and probes from 
> this show in OpenSIP log
> Am I missing some other configuration ?   Does SylkServer do any 
> checking of domain names - e.g. lookup _sip SRV (or NAPTR) records or 
> always obey the outbound_proxy setting.
> xmpp_trace
> ~~~~~~~~~~
> 2013-10-01T12:49:43.864395+01:00 [sylk-server 31836]: RECEIVED: Packet 
> 13, +0:02:49.344527
> <?xml version='1.0'?><stream:stream 
> xmlns:stream='http://etherx.jabber.org/streams' xmlns='jabber:server' 
> xmlns:db='jabber:server:dialback' from='myinternal.com' 
> to='myexternal.com' version='1.0'>
> --
> 2013-10-01T12:49:43.865468+01:00 [sylk-server 31836]: SENDING: Packet 
> 14, +0:02:49.345600
> <stream:stream xmlns:stream='http://etherx.jabber.org/streams' 
> xmlns='jabber:server' xmlns:db='jabber:server:dialback' version='1.0' 
> from='myexternal.com' id='02670d727b969693'>
> --
> 2013-10-01T12:49:43.866342+01:00 [sylk-server 31836]: SENDING: Packet 
> 15, +0:02:49.346474
> <stream:error><host-unknown 
> xmlns='urn:ietf:params:xml:ns:xmpp-streams'/></stream:error>
> --
> 2013-10-01T12:49:43.866851+01:00 [sylk-server 31836]: SENDING: Packet 
> 16, +0:02:49.346983
> </stream:stream>
> --

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