I have a WebSphere application server 8, where I have deployed an enterprise application. Now I want to make that web GUI of that application reachable. So I set up a port (9080), added a web container transport chain, added a virtual host for port 9080, and added that virtual host to my deployed application. However, it is not reachable.
Digging through WebSphere's log, I found this message:
TCPC0001I: TCP Channel TCP_6 is listening on host * (IPv6) port 9080.
So apparently, the channel listens on IPv6, not on IPv4. I verified this with netstat, which indeed shows that the server's process only listens on IPv6. How do I make the channel listen on IPv4 instead? I already tried setting java.net.preferIPv4Stack=true in the server's JVM, but that didn't change anything.
Interestingly, Websphere's console is available via IPv4, but I cannot figure out what part of it is configured differently so that it works, while my setup does not.
On many operating systems IPv6 sockets on the wildcard address (* or ::/0) can accept both IPv4 and IPv6 connections. On for example Mac OS netstat would show such sockets as i.e. tcp46 to show they are dual-stack. Other operating systems, including Linux, just show them as tcp6 even if they also accept IPv4 connections.
So it is probably listening on IPv4 just fine, it's just a confusing way of showing it to the sysadmin.