[users] problem with downloading headers with yum

[Maarten Stolte]

Hello,

I'm having a weird problem with yum. If I run yum update, I get output
like this:
---> Package mysql.i386 0:5.0.22-2.1.0.1 set to be updated
---> Downloading header for lftp to pack into transaction set.
lftp-3.5.14-1.el5.rf.i386 100% |=========================|  12 kB    00:00
http://www.mirrorservice.org/sites/apt.sw.be/redhat/el5/en/i386/dag/RPMS/lftp-3.5.14-1.el5.rf.i386.rpm:
[Errno -1] Header is not complete.
Trying other mirror.

It seems like the packages from CentOS 5 don't have the problem, as
they are listed without errors, I assume(!) the headers for those
files are downloaded.
Looking at the firewall it seems like its some problem with our
servers ip being different for incoming and outgoing, what I mean is
that a request to our hostname is resolving to another ip then how
other servers see us if we request a file there.

Is there something in YUM which I can change to work around this?

regards,

Maarten