What binds to the first interface? Please be specific.
Multicast clustering binds on the first interface. Does it use "hostname" to get the ip address?
If you start JBoss like this, with no other jgroups-related system properties set:
./run.sh -b 0.0.0.0 -c ...
JBoss will detect that 0.0.0.0 is invalid for JGroups binding and will set system property jgroups.bind_addr to the value of java.net.InetAddress.getLocalHost(). That in turn will resolve the InetAddress associated with the machine's host name.
So, configure your OS to ensure the machine's hostname resolves to the interface you want.