Enlightenment needed on file transfer

[Darren Tucker]

Xavier Cazin wrote:
> When connecting to the Internet through an RTC PPP link to a certain
> provider, file transfers from a remote host (debian potato) to my
> local host (debian woody) get immediately stuck when issued from the
> local host, while they work very well when issued from the remote
> host.

Is there a firewall or packet filter? If there is then it might be an
MTU problem. Check the MTU on both your PPP interface and remote host's
ethernet and set the higher one to equal the lower (or drop both to 576
and work up until it breaks).

Also check both hosts to see if their path MTU discovery is enabled (cat
/proc/sys/net/ipv4/ip_no_pmtu_disc should be 0).

You might need to play with the MTU settings as this can be something of
a black art due to the number of variables: host behaviour, mtu's, pmtu
discovery, firewall behaviour, every link MTU between hosts, phase of
the moon.... you get the idea.

		-Daz.