anchor.diff:          home = "/var/empty";
         };
   
  -    environment.etc = singleton
  +    environment.etc = [
         { source = "${pkgs.openssh}/etc/ssh/moduli";
           target = "ssh/moduli";
  -      };
  +      }
  +      { source = knownHostsFile;
  +        target = "ssh/ssh_known_hosts";
  +      }
  +    ];
   
       jobs.sshd = {
   
  
positive.code: 
    hktn = attrByPath [cfg.hostKeyType] (throw "unknown host key type `${cfg.hostKeyType}'") hostKeyTypeNames;
    hktb = attrByPath [cfg.hostKeyType] (throw "unknown host key type `${cfg.hostKeyType}'") hostKeyTypeBits;
  
    userOptions = {
      openssh.authorizedKeys = {
  
negative.code:         description = "Verbatim contents of <filename>sshd_config</filename>.";
        };
  
        knownHosts = mkOption {
          default = {};
          type = types.loaOf types.optionSet;
          description = ''
            The set of system-wide known SSH hosts.
          '';
          example = [
            { 
              hostNames = [ "myhost" "myhost.mydomain.com" "10.10.1.4" ];
              publicKeyFile = ./pubkeys/myhost_ssh_host_dsa_key.pub;
            }
            { 
              hostNames = [ "myhost2" ];
              publicKeyFile = ./pubkeys/myhost2_ssh_host_dsa_key.pub;
            }
          ];
          options = {
            hostNames = mkOption {
              type = types.listOf types.string;
              default = [];
              description = ''
                A list of host names and/or IP numbers used for accessing
                the host's ssh service.
              '';
            };
            publicKeyFile = mkOption {
              description = ''
                The path to the public key file for the host. The public
                key file is read at build time and saved in the Nix store.
                You can fetch a public key file from a running SSH server
                with the <literal>ssh-keyscan</literal> command.
              '';
            };
          };
        };
  
      };
  
      users.extraUsers = mkOption {
  