Strange network problem

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Hi all,

We have 2 servers located at the same hosting company.
Both are behind the same firewall.
Both have 2 network cards.

On both machines
1st netcard schema is: 192.168.a.x [NET1] (behind hosting company
firewall)
2nd netcard schema is: 192.168.b.x [NET2] (behind our firewall)

[NET1] is on DMZ and NAT works for HTTP requests.
Machine 1 worked fine for more than a year.
We recently added Machine 2 (2 months ago)

We are connected to both machines [NET1] from our office through VPN.

Now, both was working fine without any problem.
But for some reason at an unknown time, we loose Machine 2 connection.
But it is very strange.
Here are the symptoms for that second machine after problem occurs:
1. We can clearly ping all the time
2. We can telnet to SQL port or any other port we want.
3. We can see SQL is active from enterprise manager
4. We cannot see list of databases or basically we cannot do anything with
SQL other than item 3
5. We cannot do remote desktop.
6. We can remote desktop with its public IP
7. We can do all SQL tasks with its public IP
8. We can remote desktop to Machine 1, and then remote desktop to Machine 2
all using [NET1]
9. We can even do some windows based checks using our monitoring service (it
connects over TCP and logs into windows and gets values)

But we do not want to have public access to that machine.

Our tech support guy says
1. Switch may be bad, it needs rebooting
2. Windows is blocking for some reason.
I think
3. It is the firewall or VPN settings or corruption



Do you have any clue why we this problem happens all of a sudden?
How can this be fixed?
What may be the source of the problem?
Can it really be #1, or #2?

Thanks in advance
--

SevDer
http://www.sevder.com
A new .NET Source For .NET Developers



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