Weird access.log - am I being used as a proxy?

[sylvester_0]

Hello all, Ihave some concerns with the contents of my /var/log/access.log. It looks like my apache installations are maybe being used as proxies. Please see the full logs here: http://pastebin.com/f2e8532f7

As highlighted in the pastebin entry, I tried setting my workstation on my local subnet to use one of the apache machines as a proxy and all I got back is the "It works!" page. I've never seen so much "garbage" in apache logs before. Has this become the norm? Are these just "harmless" scans? Obviously none of the contents of this log exist on my server at all (horde, roundcube,etc)

Thanks for your help!

[till]

This is harmless, as you see they are all getting 404 errors. ISPConfig does not configure your server as a proxy.