Here is some code to determine the local host name that is supposed to work on a multi-homed box:
/**
* Work out the first local host name by iterating the network interfaces
*
* @return
* @throws SocketException
*/
private String findFirstLocalHostName() throws SocketException {
Enumeration<NetworkInterface> ifaces = NetworkInterface.getNetworkInterfaces();
while (ifaces.hasMoreElements()) {
NetworkInterface iface = ifaces.nextElement();
Enumeration<InetAddress> addresses = iface.getInetAddresses();
while (addresses.hasMoreElements()) {
InetAddress add = addresses.nextElement();
if (!add.isLoopbackAddress() && add.isSiteLocalAddress()) {
return add.getHostName();
}
}
}
throw new RuntimeException("Failed to determine local hostname");
}
Does the call to isSiteLocalAddress introduce a bug? I can't find any useful information about this method, but I have a feeling that it relates to IP v 6 only and is deprecated.
The method is definitely not deprecated and it's definitely not just used in IPv6.
In IPv4 there are 3 network address ranges that are defined for site-local addresses: 10/8, 172.16/12 and 192.168/16.
Reading Inet4Address.isSiteLocalAddress() shows that addresses from exactly those 3 networks will return true on those methods.
IPv6 has a similar concept, here these addresses are called unique local addresses.
Effectively this tells you if the address you have is definitely not a public one (note that even if this method returns false, the address might still not be public).