Strange Networking Problems

  • Thread starter Thread starter Damond
  • Start date Start date
D

Damond

Hi all,

I've been having this problem for about a month now. I've tried
everything I know to figure it out but still can't find a solution.
I've used ethereal to try to trace the networking information but
didn't show up anything viable.

Here's the situation. I have a windows 2000 machine. Seems that
after a few hours or so, the network connection "partially" dies on
the machine. There's another win2k machine on the same network that
works fine.

I access the "broken" one virtually through the working one. So, I
know internally everything works. I can ping each other and also
access TCP services between both.

However, when I try to go outside to the internet, the "broken"
doesn't work. It did for the few hours right after a reboot. But
then it stops working. The internal network connection and services
work fine. Here's an example of what the machines do:

*****

[WORKING MACHINE]

C:\>ping ftp.freebsd.org

Pinging ftp.freebsd.org [204.152.184.73] with 32 bytes of data:

Reply from 204.152.184.73: bytes=32 time=20ms TTL=49
Reply from 204.152.184.73: bytes=32 time=20ms TTL=49
Reply from 204.152.184.73: bytes=32 time=20ms TTL=49
Reply from 204.152.184.73: bytes=32 time=20ms TTL=49

Ping statistics for 204.152.184.73:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 20ms, Maximum = 20ms, Average = 20ms

C:\>ftp ftp.freebsd.org
Connected to ftp.freebsd.org.
220 freebsd.isc.org FTP server ready.
User (ftp.freebsd.org:(none)): ^C

C:\>ftp sun01.internal.com
Connected to sun01.internal.com.
220 sun01 FTP server ready.
User (sun01.internal.com:(none)):
[NON-WORKING MACHINE]

C:\>ping ftp.freebsd.org

Pinging ftp.freebsd.org [204.152.184.73] with 32 bytes of data:

Reply from 204.152.184.73: bytes=32 time=21ms TTL=49
Reply from 204.152.184.73: bytes=32 time=20ms TTL=49
Reply from 204.152.184.73: bytes=32 time=20ms TTL=49
Reply from 204.152.184.73: bytes=32 time=20ms TTL=49

Ping statistics for 204.152.184.73:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 20ms, Maximum = 21ms, Average = 20ms

C:\>ftp ftp.freebsd.org
ftp: connect :Connection timed out
Click to expand...
ftp> bye

C:\>ftp sun01.internal.com
Connected to sun01.internal.com.
220 sun01 FTP server ready.
User (sun01.internal.com:(none)):
*****

Machine info: Win2k, SP4


The machine still runs fine internally as if nothing's wrong. So, I
know the network card is working. And my firewall isn't blocking the
machine because it does work after a reboot. Any ideas?

Thanks,
-- Damond
 
Hi John,

First off, thank you for your reply.

This machine's ip is statically set. I can still ping and traceroute
outside, too. However, if I do ftp or telnet, it just sits there and
times out. The older machine is behind the same firewall and has an
internal address too. So, I figure it's not a reverse name lookup
error, either. If you have any more ideas for me to try, please feel
free.

I appreciate your efforts.

-- Damond

John Wunderlich said:
(e-mail address removed) (Damond) wrote in
The machine still runs fine internally as if nothing's wrong. So, I
know the network card is working. And my firewall isn't blocking the
machine because it does work after a reboot. Any ideas?
Click to expand...

It seems that most of the time symptoms like this occur it is due to
the firewall. The computer gets a DHCP local IP address from [your
router] at boot time that expires after a certain lease period. To
renew the lease, it is necessary to communicate to the DHCP server
[your router] on ports 67 & 68 to negotiate/renew the lease.
Communication on these ports is not required for the initial lease but
is to renew. If these ports are blocked by your firewall, your network
lease will expire resulting in symptoms similar to what you are seeing.

You might want to check your router configuration and see if the
configured lease time coincides with the time before your machine
starts having problems.

HTH & Good Luck,
John
Click to expand...
 
(e-mail address removed) (Damond) wrote in
First off, thank you for your reply.

This machine's ip is statically set. I can still ping and traceroute
outside, too. However, if I do ftp or telnet, it just sits there and
times out. The older machine is behind the same firewall and has an
internal address too. So, I figure it's not a reverse name lookup
error, either. If you have any more ideas for me to try, please feel
free.
Click to expand...

This is a wierd one. Long shot: Since you are statically assigning the
IP, the only other thing I can think of is that perhaps there is
another machine on the subnet that has been assigned the same IP
address. If it activates, it can hijack the connection. Try assigning
another IP address (on the same subnet) to the machine.

Lots of Luck...
John
 
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