Common Ports:
Here you can see some examples of software that open live ports if built in options are enabled which can cause conflicts

FR24:
RAW: 30002 (DVBT) / 30334(other hardware)
BS: 30003
SBS: 20072
RTL1090:
Raw out: 31001
BS out: 31004
Kinetic Basestation:
RAW out: 30006
BS out: 30003
SDR: 30005
AIS: 30007
SBS3 'standalone' mode: 10001, 30006
Dump1090:
AVR Raw out: 30002
Beast out: 30005
Dump1090 BS out: 30003
AVR In: 30001

https://discussions.flightaware.com/t/what-ports-are-used-by-piaware-2-1-3-dump1090/17384

30001 - Inbound - RAW Format

30002 - Outbound - RAW Format

30003 - Outbound - Base station Format

30004 - No Longer Used??? unless you have it configured manually

30005 - Outbound - Beast format

30104 - Inbound - mlat data

Is this correct?

Yes, this is the default config of Flightaware’s latest dump1090 package. 30104 is a generic Beast-format input port, you can give it things other than mlat.

piaware itself listens on no ports. It connects to piaware.flightaware.com:1200 50 for feeding data, localhost:30005 for receiving data, and by default it connects to localhost:30104 for returning mlat results. Also, outbound UDP to a port in the range 4999…9999 on whichever FlightAware host it connects to.