Why does the ssh daemon set up two processes?

[Overworked_PhD]

When I ssh from my home machine to a remote machine, I see the following

% ps waux | grep cd
root 97334 5.6 0.3 6272 2968 ?? Ss 8:10PM 0:01.03 sshd: cd [priv] (sshd)
cd 97337 0.9 0.2 3736 2468 p5 SNs 8:10PM 0:00.14 -zsh (zsh)
cd 97336 0.0 0.3 6260 2984 ?? SN 8:10PM 0:00.02 sshd: cd@ttyp5 (sshd)

Why do I have two instances of ssh? Ie one for root and one for my username cd?

[matsp]

One is the actual daemon that runs the ssh base-protocol. But since that HAS to run as root, you don't want that process to actually perform your commands on the other end, so it forks and resets the user-id to your personal user-id [it actually will do that even if you are logged in as root, since it still wants to run all commands for one session in one process, rather than having a bunch of commands come into the same process from differens sessions, that would be hard to track - for example, you would have to deal with multiple "current working directory" for two different sessions - messy].

--
Mats

[Overworked_PhD]

Okay, that makes sense. Thanks.