This should work just fine (proxying at network layer without Smack). We’'re actually talking about building support for this type of thing directly into Jive Messenger. The advantage of having direct server support is that you could use only a single connection between the proxy and the server. So:
a --> |-------------| |------------|
b --> | proxy | --> | server |
c --> |-------------| |------------|
In that case, three clients (a, b, c) connect to the proxy, and then the proxy makes one connection to the server. We’‘re calling this the “router” protocol. If you just use normal network proxying, you’‘d need to have an individual connection for each client between the proxy and server. There’'s more discussion about this in the latest Jive Messenger group chat transcripts.