anchor.diff:      }
     else 
       throw "You must either specify contents of the config file or the config file itself for GVPE";
  +
     ifupScript = if cfg.ipAddress == null || cfg.subnet == null then 
        throw "Specify IP address and subnet (with mask) for GVPE" 
      else if cfg.nodename == null then 
  
positive.code:         chown root /var/gvpe
          chmod 700 /var/gvpe
          cp ${finalConfig} /var/gvpe/gvpe.conf
  	cp ${ifupScript} /var/gvpe/if-up
        '';
  
        inherit exec;
  
negative.code: 
  let 
    inherit (pkgs.lib) mkOption mkIf;
  
    cfg = config.services.gvpe;
  
    finalConfig = if cfg.configFile != null then 
      cfg.configFile
    else if cfg.configText != null then
  