...
Port 22 and 443 for access to bitbucket.org - this is essential.
Port 443 on downloads.interfaceware.com so you can get upgrades - essential for safe operation of IguanaX.
Port 7888 on crashreport.interfaceware.com is for crash reports - essential if you care about reliability
If you would like access to snapshot updates then consider opening these ports:
Windows snapshots - https://winbuild.interfaceware.org:7777/