I just solved a * problem with IP Masquerading and NNTP connections;
I saw that there were some others who had the same problem on DejaNews
but no solutions were posted. For the benefit of these folks I'll post
what I found out:
The situation is one where a linux box is IP Masquerading for an
internal network. The masq server is connected to an ISP across a ppp
phone connection. The symptom of the problem is that, while most Web
site and other type of connections work, nntp and some sites do not.
Typically, a connection actually starts, but little or no data comes
The problem seems to be that automatic MTU path discovery does not
happen across the IP Masq connection. It is therefore necessary to set
the MTU of the outgoing PPP connection (on the masq server) to a low
value - I used 552 (512 bytes data + 40 byte header) and the same on the
client boxes. This prevents the stalling problem normally seen.
I note that 552 is the maximum that works for me - setting it to 576
(another frequently recommended value) doesn't work.
Anyway, I hope this helps those folks that were reporting this problem.