Unable to Surf by IP when using Squid as a transparent Proxy

I have a couple of different offices that use Linux boxes as combined routers and transparent proxies.  All of them are working fine, apart from one which is having a weird issue when attempting to view a web page via IP.  Using this website as an example, if I surf to;


It works fine.

However, if I surf to;

It will immediately drop me to a standard 'page cannot be displayed' message.

If I bypass the transparent proxy, say by trying to load the page on the router itself, it works fine, so I don't believe it is an ISP issue.

My other locations using seemingly identically configured proxies can access pages by IP fine.
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Can you see your attempt in the squid logs (access.log, store.log) ?
ropetinAuthor Commented:
No, the page view attempts do not show up in either log file.
You see, if squid is configured in transparent mode it have to know where You really want to go. It uses the name You enter into browser as destination.
If You enter ip, and therefore there;s no Host: http/1.1 request header, squid does not know where to go? It have to drop it.
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ropetinAuthor Commented:
So the question I have is, why do 6 seemingly identically configured squid proxies, seem to not  have a problem?

How do you redirect the traffic to the transparent proxy ? Switch ? Router ?
ropetinAuthor Commented:
The box that is running the squid proxy is the router.  I have the users connected via a generic workgroup switch.

Have you compared the router (redirection) settings with the other 6 proxies ?

Perhaps you should look at what kind of logging you can enable on router level ?

ropetinAuthor Commented:
By router settings you mean the iptables configuration?  I don't 100% understand iptables, but I don't see anything that would make it drop unresolved IPs.  Any suggestion how I can verify?
This might be a browser specific issue. Look here:


Go down to the section "Disadvantages of Transparent Caching"

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