Why is my Mac listening on port 625?

My Mac is listening on port 625. This listing by Apple of common ports used by macOS and Apple software claims that it has something to do with Open Directory. However, my machine doesn't have any sharing services on or is connected to any Open Directory services.

The service listening on this port is launchd, so it's likely a system service.

Any idea why this could be the case? What purpose does this listening connection likely serve?

EDIT: Here is the output of sudo lsof -i -P | grep -i "listen":

launchd      1           root   20u  IPv6 0x6cc93710b811f751      0t0    TCP *:625 (LISTEN)
launchd      1           root   27u  IPv4 0x6cc93710b81227b9      0t0    TCP *:625 (LISTEN)
launchd      1           root   31u  IPv6 0x6cc93710b811f751      0t0    TCP *:625 (LISTEN)
launchd      1           root   32u  IPv4 0x6cc93710b81227b9      0t0    TCP *:625 (LISTEN)
launchd      1           root   52u  IPv6 0x6cc93710b811fc91      0t0    TCP *:2300 (LISTEN)
launchd      1           root   53u  IPv4 0x6cc93710b8121ec1      0t0    TCP *:2300 (LISTEN)
launchd      1           root   54u  IPv6 0x6cc93710b811fc91      0t0    TCP *:2300 (LISTEN)
launchd      1           root   55u  IPv4 0x6cc93710b8121ec1      0t0    TCP *:2300 (LISTEN)
vpnagentd   62           root    5u  IPv4 0x6cc93710b81242a1      0t0    TCP localhost:29754 (LISTEN)
ciscod      65           root    3u  IPv4 0x6cc93710b81239a9      0t0    TCP localhost:1023 (LISTEN)
mtmfs      103           root    3u  IPv4 0x6cc93710b81215c9      0t0    TCP localhost:49152 (LISTEN)
mtmfs      103           root    5u  IPv4 0x6cc93710b81230b1      0t0    TCP localhost:49153 (LISTEN)
Nylas\x20  652          brett   38u  IPv4 0x6cc93710ca132ec1      0t0    TCP *:2578 (LISTEN)
Dropbox    701          brett  119u  IPv6 0x6cc93710bed7e751      0t0    TCP *:17500 (LISTEN)
Dropbox    701          brett  120u  IPv4 0x6cc93710cb0119a9      0t0    TCP *:17500 (LISTEN)
Dropbox    701          brett  152u  IPv4 0x6cc93710cb1410b1      0t0    TCP localhost:17600 (LISTEN)
Dropbox    701          brett  158u  IPv4 0x6cc93710ca7369a9      0t0    TCP localhost:17603 (LISTEN)
SpotifyWe  806          brett    5u  IPv4 0x6cc93710c9a0cec1      0t0    TCP localhost:4370 (LISTEN)
SpotifyWe  806          brett    6u  IPv4 0x6cc93710c9a0fb99      0t0    TCP localhost:4380 (LISTEN)
postgres   899          brett    5u  IPv6 0x6cc93710beef5211      0t0    TCP localhost:5432 (LISTEN)
postgres   899          brett    6u  IPv4 0x6cc93710c9a0d7b9      0t0    TCP localhost:5432 (LISTEN)

Solution 1:

Anything running it should be within this scope.

dec_dlm - DEC DLMIANA - ipcserver

Mac OS X RPC-based services. Used by NetInfo, for example.

Appledec_dlm - Directory Service Proxy (DSProxy) (Unregistered Use). DirectoryService, Open Directory Assistant, Workgroup Manager. Note: This port is registered to DEC DLM.

Source: http://www.adminsub.net/tcp-udp-port-finder/625

If it is not one of the following, try reading into the launchd docs that some really nice person made. To see all launchd events, open terminal, and paste this launchctl list if that doesn't help, type sudo launchctl list to see what the root user is launching.

Solution 2:

Port 625 is used by the opendirectoryd daemon. This is the daemon that is in charge of talking to the directory system. The most common two purposes you might use it's services are for authentication, it looks up accounts and passwords, and for service discovery, it keeps an eye out for servers and such like on the network.

Disabling it would not be a good idea. If you use kill or killall to kill it then launchd will just respawn it.