Strange Network Problem, access timing out from 1 network

[nikpreek]

Hi Gurus,

Scenario: I've come across a strange network problem. I host a web server (Win2K3) on a virtual PC (host is Win XP), here in UK. I redirect my website using DNSExit and been using it for different apps since last 2 years. I have only 5-6 concurrent users. Most of the users are from a office in India.

Problem: Since yesterday no one from the India office can access my website (Sorry, I can not give web address). I asked them to try from a neighboring office and its working fine. I can access it all from UK (I tried from 3-4 locations) and it works fine.

Solution Attempts: I tried to see if my antivirus or firewall is blocking the IP for India office, but no event log or any other information could be found.
I even asked them to do DNS flush on 1 PC but still no luck. TRACERT too times out as my ping from that network.

Can someone please help me diagnose it and solve the problem?

Thanks in advance for help.

Regards,
Nik

[sicarie]

Nik,

I'd suggest starting at one end and trace the connection through.

So, for example, starting at the remote office (as they're initiating the connection).

1) Do they have access to the internet?
2) Do they have access to UK sites?
3) Can they ping the gateway to your LAN?
4) Can they access other resources on your LAN?
5) Does your computer see the incoming traffic?

Then, once you find out where the connection is not going through, you can focus on either that system, or the system right before it (if the connection isn't coming into that system, it's 'not coming' from the system before it; if it is coming into the system, but not going out (possible on gateways/firewalls) then you can look at that system)

[nikpreek]

Hi Sicarie,

Thank you very much for your response.

I checked following and found these:
1) They have internet access.
2) They can access UK sites, with no problem.
3) They cant ping my IP (request times out). Even tracert shows that my Virgin Media gateway name for the IP, but even in this case the request times out.
4) They can't ping / connect any website (IIS / Apache) or even ftp / telnet on my LAN in UK.
5) How do I see this? I can't see it in IIS logs or event viewer. I'm using McAfee and cant see anything in there (warning / error etc).

So overall, I can confirm that it is only my network (IP) they can not access. (I use Dynamic IP routing, but it has not changed since last few months, so I'm not doubting the local DNS for them. Also, direct IP ping too is not working, so I cant doubt it)

Shall I call Virgin Media if they have blocked it?

Which other place / tool I can use to see who is blocking it?

Thanks again for the help.

Regards,
Nikhil

[nikpreek]

LOL.... Sorry guys. It was just me being ignorant and stupid to jump for the questions. I had checked both the firewalls (Host & VM) for windows, event viewer and McAfee Firewall events. Today I noticed a new option in firewall named NetGuard (don't know since when it was installed). It had blocked the IP for the India office.
I just disabled all firewalls and problem was solved. It gave me clear indicator that one of the firewall is blocking it. Then noticed this new head in McAfee. Added the IP to safe list in NetGuard and all is working fine.
Thanks Sicarie for steps which helped me diagnose the problem.
Hope this helps someone else too...
Regards,
Nik