Having just spun up the docker on 16:04 image. There is a notification upon login suggesting we enable the ufw firewall rules.

The default rules are set as

[ 1] 22                         LIMIT IN    Anywhere                  
[ 2] 2375/tcp                   ALLOW IN    Anywhere                  
[ 3] 2376/tcp                   ALLOW IN    Anywhere                  
[ 4] 22 (v6)                    LIMIT IN    Anywhere (v6)             
[ 5] 2375/tcp (v6)              ALLOW IN    Anywhere (v6)             
[ 6] 2376/tcp (v6)              ALLOW IN    Anywhere (v6)

I understand that 22 is required for ssh however what are ports 2375 & 2376 used for?