Nut upsuser - Dec 2007 - Upsmon and Winnut disconnect regularly

Hi All!

This time I'm using Nut 2.2.0, Debian etch and kernel v. 2.6.23.9.
My hardware config is quite simple. There are 2 PCs connected to my
PowerMust 600VA. One is mensioned above the other is a Windows PC
using Winnut 2.0.0b. The Linux PC is connected to the UPS via a
serial cable and acts as the server.

The problem is that both upsmon and winnut disconnect regularly but
in random moments. First I've been using kernel v. 2.6.22.1 and
tried upgrading it to the version mensioned, but I've reached the
same results. Remembering that I've been using Nut 2.0.0 succesfully
a few years ago, I've tried that version again, but with the same
results. Then I realized that I've been using kernel v. 2.6.10 that
time, so there can be some problems.

I've analized the network traffic between the two PCs and realized
that maybe I have problems with the delayed ACKs. And at this point
I have no idea how to continue.

Can anyone help me?

Thanx in advance!

Bye: Steve

On Dec 28, 2007 6:19 AM,  <stevesz at enternet.hu>
wrote:
> This time I'm using Nut 2.2.0, Debian etch and kernel v. 2.6.23.9.
> My hardware config is quite simple. There are 2 PCs connected to my
> PowerMust 600VA. One is mensioned above the other is a Windows PC
> using Winnut 2.0.0b. The Linux PC is connected to the UPS via a
> serial cable and acts as the server.
How are the Linux PC and Windows PC connected on the network side? Is
it just via a switch, or is there another device in between, like a
firewall? Are there any software firewalls involved?
> The problem is that both upsmon and winnut disconnect regularly but
> in random moments. First I've been using kernel v. 2.6.22.1 and
> tried upgrading it to the version mensioned, but I've reached the
> same results. Remembering that I've been using Nut 2.0.0 succesfully
> a few years ago, I've tried that version again, but with the same
> results. Then I realized that I've been using kernel v. 2.6.10 that
> time, so there can be some problems.
>
> I've analized the network traffic between the two PCs and realized
> that maybe I have problems with the delayed ACKs. And at this point
> I have no idea how to continue.
I am not 100% sure, but I don't believe that NUT does anything special
for TCP connections. So in theory, you should see the same sorts of
problems on any service that keeps a TCP connection open for a long
time.

For instance, on the linux box, if port 12345 is open, you could
install netcat (nc) and run:

   $ nc -vlp 12345

And on the other machines, you could try telnet'ing to port 12345
("telnet linux-box 12345" or "nc -v linux-box 12345") and
see how long
the connection stays up.

-- 
- Charles Lepple