telnet/ssh disconnects... Possible NAT teardown?

[Jeremy]

Alright, I'm using Fedora Core 1.  My box is setup as a router for the rest of
my network.  It has two network cards, one 10 base card connected to a cable
modem, and another 10/100 connected to my network switch.  I have iptables
setup to do masquerading.

The problem...

Telnet/SSH connections to the machine, from the outside world, disconnect after
5-10 minutes of inactivity.  For example, I can have 3 SSH connections to my
box, neglect one window for a few minutes, and when I go to that window and
start typing, I get a message from PuTTY saying I got disconnected.

I've looked extensivly on the net trying to figure out what's wrong and how to
fix it.  I've come across a couple sites saying that this could possibly be
caused by a 'NAT teardown'.  I'm new to iptables and NAT, so i'm not exactly
sure what this means.  I was under the impression that NAT timeouts on
CONNECTED connections was like 5 days of inactivity before it would drop.  When
I cat /proc/net/ip_conntrack, i see my connections, and I see they have very
high timeouts.

I've looked through the iptables man page, as well as the iptables/netfilter
website, and i can't find anything relevent to this.  Does anyone know how I
might fix this?

-Jeremy

__________________________________
Do you Yahoo!?
Yahoo! Finance: Get your refund fast by filing online.
http://taxes.yahoo.com/filing.html