Forum OpenACS Q&A: Re: Using Apache1.3.28 no ssl, attempting VirtualHosts and ProxyPass ...

This is almost exactly the wrong place to post this, since the vast majority here use AOLserver, but here goes nothing!

1.3.27 (RedHat version, from rpm):

Possibly relevant bits of httpd.conf:
<IfModule mod_proxy.c>
    ProxyRequests Off
</IfModule>

<VirtualHost *>
    ServerAdmin youremail@somewhere
    ServerName somewhere.acornhosting.net
    ServerAlias otherdomain.acornhosting.net
# do not turn proxyrequests on!
# turning proxyrequests on can allow your server to be exploited as an open proxy
# needless to say, this is a baaaad thing
# and will get you into major hot water with your upstream provider
    ProxyRequests Off
    ProxyPass / http://1.2.3.4:8000/
    ProxyPassReverse / http://1.2.3.4:8000/
    NoCache *
</VirtualHost>

Hope that helps.  If not, you might try an Apache-related mailing list or forum?