nixos-config/config/programs/ssh.nix

{...}: {
  programs.ssh = {
    controlMaster = "auto";
    controlPersist = "10m";
    enable = true;
    matchBlocks = {
      "build-nas" = {
        hostname = "backup.int.chir.rs";
        identitiesOnly = true;
        identityFile = "~/.ssh/id_ed25519";
        port = 22;
        user = "darkkirb";
      };
      "build-pc" = {
        hostname = "nutty-noon.int.chir.rs";
        identitiesOnly = true;
        identityFile = "~/.ssh/id_ed25519";
        port = 22;
        user = "darkkirb";
      };
    };
  };
}