The default arguments configuration runs the crawler with DHT, UPnP forwarding and upload (listen) features disabled, but the current librqbit implementation still likely handles PEX connections. Use the following tips to enhance your privacy, in addition to the firewall rules.
The P2P Blocklist
Use the P2P Blocklist argument to filter outgoing connections:
aquatic-crawler --blocklist=file:///path/to/blocklist.txt {OTHER_ARGUMENTS}
or
aquatic-crawler --blocklist=http://domain.to/blocklist.txt {OTHER_ARGUMENTS}
Examples
Block all connections to IPv4
# blocklist.txt
IPv4:0.0.0.0-255.255.255.255
Debug connections
See the Debug page. For system traffic debug, use etherape or similar software.