Metronet communication problems

[#1]

I need to communicate between 2 machines at different properties with different broadband providers, one on Metronet the other on Virgin Media. I use Remote desktop, VNC, SSH -- that kind of thing. This has worked perfectly for a number of years.
A couple of weeks ago my Virgin IP address changed, having been the same for several years even though it's nominally dynamic. I now find that I can communicate perfectly *from* the machine on Virgin *to* the one on Metronet, but not the other way around. Not even pings. I *can* reach the Virgin machine from other networks, e.g. the one at my place of work. The IP address of the Virgin machine is showing up correctly in DNS.
I'm assuming this is a routing problem of some kind, in one or both of the networks. Any ideas? I can provide the actual IP addresses if someone from Metronet support would care to get in touch.
Thanks.

[#2]

What router are you using on the Metronet connection?  Is there anything in it's firewall that might have had the old IP address specifically set?
Phil

[#3]

Try running a traceroute, that should show you where the connection fails;

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and Settings\chilly>tracert 84.51.xxx.xxx
Tracing route to 84-51-xxx-xxx.peterxxxx.adsl.metronet.co.uk [84.51.xxx.xxx]
over a maximum of 30 hops:
  1     1 ms    <1 ms    <1 ms  router [172.17.16.101]
  2    42 ms    29 ms    28 ms  lo0-plusnet.pcl-ag01.plus.net [195.166.128.27]
  3    28 ms    29 ms    28 ms  gi1-2-803.pcl-gw1.plus.net [84.92.5.57]
  4   145 ms   207 ms   201 ms  te2-2.pte-gw1.plus.net [212.159.0.186]
  5    31 ms    28 ms    27 ms  vl22.thn-gw1.plus.net [212.159.4.3]
  6    33 ms    29 ms    29 ms  gi9-0-303.thn-ag3.plus.net [84.92.3.179]
  7    49 ms    52 ms    52 ms  84-51-xxx-xxx.peterxxxx.adsl.metronet.co.uk [84.
51.xxx.xxx]
Trace complete.

[#4]

Quote from: pjmarsh

What router are you using on the Metronet connection?  Is there anything in it's firewall that might have had the old IP address specifically set? Phil

It's a 3COM OfficeConnect. There are no IP-specific filters set up.

[#5]

Quote from: chillypenguin

Try running a traceroute, that should show you where the connection fails;

Yes, tried that. Not very informative:

Tracing route to xxx.dyndns.org [92.237.xxx.xxx]
over a maximum of 30 hops:
  1     *        *        *     Request timed out.
  2     *        *        *     Request timed out.
  3     *        *        *     Request timed out.
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9     *        *        *     Request timed out.
 10     *        *        *     Request timed out.
 11     *        *        *     Request timed out.
 12     *        *        *     Request timed out.
 13     *        *        *     Request timed out.
 14     *        *        *     Request timed out.
 15     *        *        *     Request timed out.
 16     *        *        *     Request timed out.
 17     *        *        *     Request timed out.
 18     *        *        *     Request timed out.
 19     *        *        *     Request timed out.
 20     *        *        *     Request timed out.
 21     *        *        *     Request timed out.
 22     *        *        *     Request timed out.
 23     *        *        *     Request timed out.
 24     *        *        *     Request timed out.
 25     *        *        *     Request timed out.
 26     *        *        *     Request timed out.
 27     *        *        *     Request timed out.
 28     *        *        *     Request timed out.
 29     *        *        *     Request timed out.
 30     *        *        *     Request timed out.
Trace complete.

By the way, I do know that DNS is reporting the correct IP address for the target machine.

[#6]

Hi there,
Are you using the Metronet firewall?  In which case have you tried turning it off?
It might be stopped your traffic routing correctly.  I appreciate it's working from other locations, but it definitely might be something worth trying.

[#7]

Hi James. Thanks for your reply. No, no Metronet firewall. (I've just checked.)
I've raised a support ticket with the actual IP addresses. Clearly this might not be a Metronet problem, but I have to start somewhere.
cp:quote

[#8]

Hmm.  I can trace to your IP address but I suspect that that doesn't tell us too much about your problem.
How much has your Virgin IP address changed?  Is it a minor one or a completely different IP address? I think by looking at the Metronet IP probably isn't helping us and we should actually be looking at the Virgin side of things instead.

[#9]

Completely different address space: it changed from 82.32.6.xxx to 92.237.136.xxx
I think you're right, by the way, about it being more likely to be a Virgin problem; but as I said I have to start somewhere.
cp:quote

[#10]

I'm not trying to detract at all from looking in to the Metronet side of things at all and I hope I didn't create that impression
Reckon it mioght be an idea for our support staff to see if they can traceroute to your new IP address and see what data they're able to get.

[#11]

Quote from: Jameseh

I'm not trying to detract at all from looking in to the Metronet side of things at all and I hope I didn't create that impression

You didn't create that impression.

Quote

Reckon it might be an idea for our support staff to see if they can traceroute to your new IP address and see what data they're able to get.

That's what I'm hoping for. I've gone as far as I can in debugging it myself. Cheers...

[#12]

Quote from: pwt300

Quote from: chillypenguin Try running a traceroute, that should show you where the connection fails; Yes, tried that. Not very informative:

Your traceroute was very informative, it did not even get out of your local network. So it looks like a local issue with the PC using the Metronet connection.
Also please can I ask you not to quote the preceding post, its unnecessary.
Chilly

[#13]

Quote from: chillypenguin

Your traceroute was very informative, it did not even get out of your local network. So it looks like a local issue with the PC using the Metronet connection.

You mean the PCs (I have several running Windows, Mac OS X and Linux) that are perfectly happily talking to every other network address except the problem one? Sorry, but I think you're wrong...

Quote

Also please can I ask you not to quote the preceding post, its unnecessary.

Well that's exactly what you did, and for good reason: that's how you tell which post is being replied to, unless there's a better way.

[#14]

OK, it's fixed. And I have to admit that it was my fault -- a generic firewall rule in the DSL router seems to be the culprit. It was passing packets to the old Virgin IP address, but not the new one. The rule-set is opaque, so I can't see what actual rules it is applying.
Thanks for your help, everyone...
I've closed the support ticket.