xmpp-logging-proxy is an XMPP intermediary (aka XMPP MITM) that acts like a server to clients, proxies communication to another XMPP server, and logs everything in plain text, even after STARTTLS negotiation.

Install: go get github.com/orivej/xmpp-logging-proxy

Given a client with JID login@server, XMPP server at server.host and proxy at proxy.host, you may either:

1. Make client connect to proxy.host instead of server.host (via client options, /etc/hosts, or DNS). Run proxy as xmpp-logging-proxy -server target.server:5222.
2. Make client use JID [email protected], and let xmpp-logging-proxy replace proxy.host with server in outgoing traffic and replace server with proxy.host in incoming traffic. Run proxy as xmpp-logging-proxy -server target.server:5222 -replace-local proxy.host -replace-remote server. The proxy will log the traffic from the perspective of the server (proxy.host will not occur in the log).