Question

OCS 2007 R2, Communicator 2007, and NATs

Asked by: tbennett35

I'm trying to set up AV conferencing via OCS 2007 R2, but I'm having a bit of a nightmare. The setup I have is as follows:

Enterprise Pool running AV conferencing server, along with IM and web conferencing
Edge server with 2 NICs, one assigned as the internal NIC, 1 assigned as the external NIC with 3 IPs assigned to it (one for each of acces edge, web conf edge and av edge)
The box is checked fot NAT translation in the AV edge configuration

All connections go via the edges. There is no concept of an 'internal' user connecting directly to the pool servers, as this is a hosted service, so clients could be anywhere.

When two clients are on the same network, it works absolutely fine, because as I understand it, comms between two users are peer to peer. If, however, I am at home and attempt to communicate with either a colleague in the office, or anyone else at their home, it fails every time.
The office location is behind a NAT and a firewall, and so am I or any of my other home based colleagues because we have our own home routers. I'm thinking that the peer to peer negotiation is failing because of NAT, but if thats the case, I don't know how to get around that. I could set up forwarding rules, which I guess would be fine for home, but which wouldn't work for the office location, given that there are multiple users there.

IM works fine by the way, irrespective of where the user is.

The external firewall has ports 3478 and 443 opened for the public address that is NAT'ed to the DMZ address of the edge server. it currently also has 5061 for IM. I've tried opening the ports that would be required for federation (even though we don't federate with anyone else...desperation) but that didn't work either.

I haven't even touched web conferencing yet, although I do know that currently it dosn't work unless on the same lan.

Surely I'm not the only one in the world with a configuration like this?

Thanks in advance for any help you might be able to offer.

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Asked On
2009-10-16 at 02:54:15ID24817543
Topics

Live/Office Communications Server

,

Network Routers

,

Networking Hardware Firewalls

Participating Experts
1
Points
500
Comments
6

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Answers

 

by: tbennett35Posted on 2009-10-16 at 03:26:50ID: 25588167

Just to expand on this a little more, I have just done a wireshark capture with a colleague who is in the office while I am at home. Wireshark shows that communicator is trying to setup comms between my private internal IP to his private internal IP, which will never work.

Is here any way around this?

 

by: gaanthonyPosted on 2009-10-17 at 07:18:08ID: 25596004

It sounds like your OCS Edge Server configuration may be missing something as the two clients when behind NAT should be getting candidates from the Edge and connect across it's relay ports.

You say the NAT check box is checked on the AV Edge Configuration.  The external AV Edge FQDN that is listed on that same page can you open a CMD prompt on the Edge and ping or resolve the AV FQDN to the external public IP?  If not, then add a host file entry on the Edge that includes the IP and External AV FQDN.

Next does the certificate on that same interface has a subject alternate name (SAN) field with entries.  If so is the Subject name (AV FQDN) listed last in the SAN.  FYI best not of have SAN entries on the AV and internal interface certificates.

Check that on the internal tab on the edge properties that the Internal servers authorized to connect to the edge include all the internal OCS Front End servers and the OCS Pool FQDN.

Check that you can telnet to each of the FQDNs for the external edge roles on their respective ports based on your configuration from the internet.

On your OCS Front End go to forest global properties and check that on the Edge Server tab you have then internal fqdn of the access edge server specified for the Access edge and same for AV Edge with port of 5062.

Verifiy you can telnet from Front End to Edge on 5062, 443, and 5061.

From Edge verify you can telnet Pool FQDN and Front End FQDNs on 5061.

On the Front End Pool Properties verify that the AV Edge Server port 5062 is selected in the dropdown for AV Edge Server.

Maybe something above will help you uncover the configuration issue.

 

by: tbennett35Posted on 2009-10-19 at 02:55:23ID: 25603794

Hi gaanthony...

I've tested all of the things you suggested with the following results:

- NAT box on AV edge properties is checked
- Can ping the external AV name from the edge server and it resolves to the public name
- Cert on the internal interface and the AV interface had SAN names that matched subjectname, however I have issued new certs with no SAN name. Both are internal. Is his ok on the AV interface? As far as I understood this was for internal authentication
- On the Internal tab, both the Front-End name and the pool name are authorized to connect to the edge
- All telnet testing to all ports specified checks out ok- On the global properties, the internal FQDN of the edge is shown using port 5062
- On the Front-End Pool Properties, AV edge is shown with port 5062

I tried starting an AV call after changing the certs, while at the same time running a debug on the edge server. There's a lot of information produced, but after looking through line by line, nothing jumps out at me, however I can provide any logs that may help. One thing I did spot was a message that said:
"ms-client-diagnostics: 52031; reason="Call terminated on media connectivity failure" "

I'm not sure whether that gives something away with respect to the root cause, or whether thats an expected message generated by my error (if that makes sense).

I'm going to try and run some more wireshark captures to see if I can spot anything obvious. Will post back if I find anything new.

Thanks

 

by: tbennett35Posted on 2009-10-19 at 03:24:19ID: 25603910

UPDATE: This appears to work now!!

I changed the certs (removing the SAN name) but forgot to restart the services. After doing that, I started another AV session with a remote user, and it worked great. The wireshark also reported the NAT address of the remote user.

I'll do more testing and confirm this is the fix. Looking good though!

 

by: tbennett35Posted on 2009-10-19 at 08:40:58ID: 25606222

More testing has been performed, and I can confirm that removing the SAN name from the internal certificate on the internal interface and the internal certificate on the external AV interface (thereby having no SANS on either of these two) worked for me. All of the other points you listed were already in place, and this was the only change I made (as well as restarting the services after re-assigning the new certs).

I don't think i would have ever done that without you specifically mentioning it, so can't than you enough!

 

by: gaanthonyPosted on 2009-10-19 at 17:11:18ID: 25610028

Glad it's working for you.

20120131-EE-VQP-002

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