proxy problem 'Name or service not known' while wget runs fine

Hi,

I am unable to get yum working behind a proxy with authentication. Wget 
works fine with:

http_proxy=http://my.proxy.intern:8080
proxy-user=user
proxy-password=pass

But if I enter in /etc/yum.conf:

proxy=http://my.proxy.intern:8080/
proxy_username="user"
proxy_password="pass"

(or without the quotes, with or without the trailing slash)

I get:

[root@server yum.repos.d]# yum list
http://linuxsoft.cern.ch/scientific/51/x86_64/SL/repodata/repomd.xml: 
[Errno 4] IOError: <urlopen error (-2, 'Name or service not known')>
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: 
sl-base. Please verify its path and try again

Running a tcpdump reveals no connection to the proxy at all by yum. I 
thought it could be a DNS problem, the machine itself can't do DNS 
lookups, only the proxy can do that. I have used the ip address, used 
/etc/hosts, used tinydns to serve linuxsoft.cern.ch, but it didn't help.
I have put the proxy in /etc/yum.conf and/or in the repo file, doesn't 
help. Wget doesn't complain about the lack of DNS. It just leaves that 
to the proxy and that works fine:

[root@server yum.repos.d]# wget 
http://linuxsoft.cern.ch/scientific/51/x86_64/SL/repodata/repomd.xml
--17:15:36-- 
http://linuxsoft.cern.ch/scientific/51/x86_64/SL/repodata/repomd.xml
Resolving my.proxy.intern... 10.0.0.1
Connecting to my.proxy.intern|10.0.0.1|:8080... connected.
Proxy request sent, awaiting response... 200 OK
Length: 1143 (1,1K) [text/xml]
Saving to: `repomd.xml'

100%[=========================>] 1.143       --.-K/s   in 0s

17:15:37 (156 MB/s) - `repomd.xml' saved [1143/1143]

I have no environment variables regarding proxies. It doesn't help if I 
do, either.


Does anyone have a clue?

thanks,

Gerben