Varnish only working with ports 80, 8080 and 9080

[Werner Randelshofer]

Dear list members,

I am new to Varnish. I am trying to configure it so that I can run a dozen or so node.js services as backends.

For some reason, Varnish only seems to work with ports 80, 8080 and 9080 either as frontend (listen) or backend ports.

When I use a different port number in VARNISH_LISTEN_PORT, then varnishd does not start. 
I made sure that the port number is not taken using the command netstat -nltp 

Also when I use a different port number as backend, then Varnish tells me that the service is unavailable, and tells me that probing fails. However the backend is fully functional, when I connect to its port number. 

Is there a configuration option that I am missing, or a way how I can debug this?

I am running varnish-3.0.3 revision 9e6a70f on CentOs 6.4.


With best regards,
Werner