What is local.blackjack from Netstat?

When running netstat I noticed the suspicious name blackjack. I wonder if it's malware.

PROMPT> netstat -v
Active Internet connections
Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)     rhiwat shiwat    pid   epid  state    options
tcp6       0      0  nameofmachine.local.blackjack fe80::c55b:ddf6:.13569 ESTABLISHED 131072 131072    476      0 0x0102 0x00000204
tcp6       0      0  nameofmachine.local.1024      fe80::c55b:ddf6:.1024  ESTABLISHED 131072 131072    476      0 0x0102 0x00000204

Looking up the pid 476

PROMPT> ps ax | grep 476
476   ??  S      0:19.94 /System/Library/PrivateFrameworks/IDS.framework/identityservicesd.app/Contents/MacOS/identityservicesd

So the process that owns the address seems to be identityservicesd.app, which is an Apple process. This is where my trail ends. There are other mentions of .blackjack occurring on macOS, see [this unanswered Reddit question](https://www.reddit.com/r/HomeNetworking/comments/cmj92b/blackjack_when_running_netstat/) . ### Question: What is it? Malware?