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Ports blocked on ADSL connection.

Posted on 2006-04-19
Medium Priority
Last Modified: 2010-05-18
I have a remote user who’s Citrix connection has stopped working but still has regular Internet access with other problems.
A notebook that usually works with Citrix is also having the same problem at the same remote site.

I suspect that the Citrix port 1494 is being blocked by the ADSL carrier (British Telecom) as the ISP Demon Internet have no idea what’s going on.

How can I prove where the connection is being blocked? I have tried a port scanner which just tells me is it can see a port or not. Ping just says destination net unreachable
C:\>pathping  -routers IP address-

Tracing route to client.com [client router IP address]
over a maximum of 30 hops:
  0  apc [Local PC IP address]
  1  demon-gw.hmg2.com [Local router IP address]
  2  anchor-hg-3-l100.router.demon.net []
  3  anchor-hg-3-l100.router.demon.net []  reports: Destination net unreachable.

It looks to me that or what’s behind it is blocking my Citrix traffic as well.

Question by:JPFN
LVL 12

Assisted Solution

Craig_200X earned 400 total points
ID: 16489609
nothing on your router/firewall has been reset at the site? you prove it by directly connecting device to the modem.. making sure no firewalls are active in the client PC. I would verify this first, then bring it to the attention of the carrier - if it is not them they should be able to prove its NOT.

LVL 20

Accepted Solution

RPPreacher earned 1200 total points
ID: 16489692
If ping is blocked, it is entirely possible the port is open, its just a corrupt routing table (at

I would contact the ISP and tell them that you are unable to ping a known good address.

Once that is resolved, then deal with the port issue (if it still is an issue)

Expert Comment

by:OAC Technology
ID: 16490651
If you say Citrix WAS working, but now has stopped, it sounds more like a licensing issue.

I had a problem where everyone would be in and happy for a while, then people would start getting kicked out and nobody would be able to connect.

Rebooting the machine solved the problem for a little while, but then the next day nobody would be able to connect.

Long story short, there was a problem with the licensing (something got corrupt), and I had to reinstall citrix and reactivate/whatever.
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Author Comment

ID: 16495461
I disabled the firewall and verified that it was off with a scan from GRC.COM I also did the same on a separate notebook.

I know it is not a licensing issue because I can access the Citrix site from other locations with the same ID etc.

Indeed it would seem that (anchor-hg-3-l100.router.demon.net []  reports: Destination net unreachable) has a corrupt routing table. As the router belongs to the ISP (Thus Demon Internet) and not the carrier (BT) I think I will recommend moving to an ISP that can manage its routers and has competent technical support.

I have talk to 4 different support people who would not accept there was a problem on their network. I have emailed the support with the pathping results but last time I did this it took over a week to get a response.

Assisted Solution

nickhills earned 400 total points
ID: 16499512
Citrix Licensing is a strange beast, just because you can login from another site with the same ID in no way means that it is not a licensing issue! Terminal Server licensing can be very fussy, and it has caught us out a few times, allowing some users in, but not others....

however....if this were the case, you would get a message telling you that you have run out of licences!!

this does sound like a connectivity problem, have you tried telnetting to the port - often this can help throw some light on what is going on.

just to clear this up, your remote user at site A (home or whatever) is trying to access a citrix server at site b (office?) via a Demon ADSL subscription that is provisioned at site A? Site B is provisioned by another carrier.

Assuming that is correct, have you tried using another ISP (dialup etc) to verify connectivity to Site B, and this rule out firewall / ISP problems at B.

you also mention another laptop at the remote site is having probelms, is that at site A, site B, or site C?

Author Comment

ID: 16503815
It gets better the ISP has now recommended that I use a web proxy to resolve the problem?
I have given the ISB an ultimatum either they resolve the problem with their router or I get the clients ADSL re-provision with another ISP. It’s a shame as a couple of years back their support was very good now I just get the run round. Quite frankly I wouldn’t trust theses guys to change a light bulb.

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