anchor.diff:  
           exec =
             ''
  -            ${pkgs.openssh}/sbin/sshd -h /etc/ssh/ssh_host_dsa_key \
  +            ${pkgs.openssh}/sbin/sshd -h /etc/ssh/ssh_host_${hktn}_key \
                 -f ${pkgs.writeText "sshd_config" cfg.extraConfig}
             '';
         };
  
positive.code:     v == "without-password" ||
      v == "forced-commands-only" ||
      v == "no";
  
    userOptions = {
      openssh.authorizedKeys = {
  
negative.code:         '';
        };
  
        hostKeyType = mkOption {
          default = "dsa1024";
          description = "Type of host key to generate (dsa1024/rsa1024/ecdsa521)";
        };
  
        extraConfig = mkOption {
          default = "";
          description = "Verbatim contents of <filename>sshd_config</filename>.";
  