> > Fetching distfiles with ftp on a host sitting behind a NAT gateway (with
> > builtin ftp proxy) is working fine from most file servers on the Net.
> > 
> > But with a few remote servers, ftp is stopping after login and cd in the
> > remote file server :  no data is received, the progress bar is showing 0%
> > and there is apparently no timeout to the stopped transfer.
> > On the other hand, fetching the same distiles from the same remote servers
> > on a host that is directly connected to the Internet (i.e. without NAT and
> > builtin ftp proxy) is always working fine.
> > 
> > Is this problem related to the NAT or to the builtin ftp proxy ?
> > Is there a workaround ? (especially related to the use of pkgsrc)
> 
> It may be a MTU-related problem. Are you behind a pppoe interface ?

Yes.


> Are you using mss clamping or some other config to reduce the TCP MSS ?

Yes. I had encountered e-mail exchange problems (more and more sendmail
daemons were started from some remote smtp servers on my host and nothing
was transfered) in the past and since them I have the following line in
/etc/ipnat.conf :

map pppoe0 192.168.1.0/24 -> 0/32 mssclamp 1440

It solved the smtp problem.


Jean-Pierre HOFER