debugging low transfer speed

[Thomas Klausner <tk%giga.or.at@localhost>]

Hi!

In the following setup:

host1 - firewall - INTERNET - firewall - firewall - host2
                                 |
                               host3

When I use scp or rsync from host1 to host3, I get ~300kb/s.
host2 to host3 is at 1MB/s or more.
host1 to host2 gives me ~30kb/s.

When I pipe data via host3 to host2, I get 300kb/s as well.

host1 is NetBSD-6.99.15/amd64; host2 is NetBSD-5.99.40/amd64; host3 is
some Linux 2.6.26/amd64.

What could be the cause that the direct connection between host1 and
host2 is so much slower? How can I debug it? How can I change it?

Thanks,
 Thomas

(Please Cc me.)