The media proxy needs to have a Jive property that can be set to override the IP address. This is necessary when using DNS SRV records. For example, the file transfer proxy service has a property that can be set:
Some servers are setup to use DNS SRV records. In that case, their domain may not the actual server address. For example, the DNS SRV record for igniterealtime.org could point to a server at xmpp.igniterealtime.org. This will affect non XMPP traffic like the file proxy transfer service, since the proxy service can't give out the normal XMPP domain name and have that work.
When this property is set, the file transfer proxy service will advertise the given IP address rather than the XMPP server domain.
Added support for this via the property "mediaproxy.externalip".