diff -up cups-1.6.3/cups/usersys.c.overriden-h cups-1.6.3/cups/usersys.c

--- cups-1.6.3/cups/usersys.c.overriden-h	2017-09-22 13:33:48.389439818 +0200

+++ cups-1.6.3/cups/usersys.c	2017-09-22 13:41:08.580033663 +0200

@@ -380,6 +380,20 @@ cupsSetServer(const char *server)	/* I -

       cg->ipp_port = atoi(port);

     }

+    if (!cg->ipp_port)

+    {

+      const char	*ipp_port;		/* IPP_PORT environment variable */

+

+      if ((ipp_port = getenv("IPP_PORT")) != NULL)

+      {

+        if ((cg->ipp_port = atoi(ipp_port)) <= 0)

+          cg->ipp_port = CUPS_DEFAULT_IPP_PORT;

+      }

+      else

+        cg->ipp_port = CUPS_DEFAULT_IPP_PORT;

+    }

+

+

     if (cg->server[0] == '/')

       strcpy(cg->servername, "localhost");

     else

@@ -390,6 +404,7 @@ cupsSetServer(const char *server)	/* I -

     cg->server[0]      = '\0';

     cg->servername[0]  = '\0';

     cg->server_version = 20;

+    cg->ipp_port       = 0;

   }

   if (cg->http)