Name resolution behind a proxy

Question

Using Linux (Debian)

At my current place of employment I'm behind an ISA proxy server, I'm not in a position to make any changes on this machine.

I'm developing software and have set up a virtual machine using kvm, almost everything works fine. The VM is on a virtual network 192.168.122.0

In /etc/profile I have the following environment variables:

http_proxy=http://x.x.x.x:8080/
no_proxy=localhost,192.168.122.0/24

I have the VM's name in /etc/hosts.

From the host I can ping the VM and connect via ssh by name.

I can't use a browser to connect to an apache server running on the VM, name resolution is passed to the ISA server and I get a failure displayed that the hostname could not be found (not surprised that corporate DNS doesn't know about my VM)..

I get the same in all browsers, so

elinks http://vmname

fails, even though

elinks -lookup vmname

returns the correct IP address for the VM.

However, "getent hosts vmname" returns the correct local IP for the VM.

If I do :

http_proxy="" elinks http://vmname

then I can connect via http fine.

Is there a configuration somewhere that I've missed? I've looked in /etc/nsswitch.conf & /etc/host.conf & /etc/resolv.conf

I notice that "host vmname" returns 2(SERVFAIL) rather than 3(NXDOMAIN). Is it possible to configure this such that I can connect both to external servers & my internal VM without re-configuring the browser for each?

Solution

Add the VM's name to the no_proxy variable.

no_proxy=localhost,192.168.122.0/24,vmname

And this should get you fixed. Your problem is that all the browsers are sending the HTTP request to your ISA proxy.

Comments

[mgorven]

Do you want traffic to the VM to bypass the proxy, or go through the proxy but fix the DNS issue?

[Andy Ruddock]

I want the traffic to the VM to bypass the proxy. The subnet the VM is on is in the no_proxy environment variable. Why do the browsers not get the address from /etc/hosts?

[Andy Ruddock]

> I have the VM's name in /etc/hosts

[Diego Woitasen]

When there is a proxy enabled, DNS resolution is done in the proxy not in the local machine.