How to update ssh configuration files in NixOs

Question

I've been playing with NixOs and was wondering how one can modify a config file. For example I tried to modify the ssh configuration file /etc/ssh/ssh_config (to allow root ) but I can't save the file, as it's only a link. I understand that modifying a file manually is not the way to do (because the system needs be aware of the modification), so what is the NixOs way to do it ?

Answer 1

See programs.ssh options.

Also note there's an extraConfig for further text in ssh_config.