You can type the command
status in monerod. This will show something like the following, in green:
Height: 1226605/1226605 (100.0%) on mainnet, not mining, net hash
51.39 MH/s, v4, up to date, 8+6 connections
The first number in the
8+6 connections part refers to the number of outgoing connections. The second number refers to the number of incoming connections.
If you see a positive number after the plus (+) sign, then your node is allowing incoming connections. In the example above, 6 incoming users are connected to my node. If it showed
8+0 instead, I would have no incoming connections on my node and it is probably not set up properly to allow incoming connections.