- Markus Moeller introduced two new options to libcurl:

CURLOPT_SOCKS5_GSSAPI_SERVICE and CURLOPT_SOCKS5_GSSAPI_NEC to allow libcurl
  to do GSS-style authentication with SOCKS5 proxies. The curl tool got the
  options called --socks5-gssapi-service and --socks5-gssapi-nec to enable
  these.

lib/urldata.h

@@ -1051,6 +1051,9 @@ struct connectdata {
   } proto;
 
   int cselect_bits; /* bitmask of socket events */
+#if defined(HAVE_GSSAPI) || defined(USE_WINDOWS_SSPI)
+  int socks5_gssapi_enctype;
+#endif
 };
 
 /* The end of connectdata. */
@@ -1366,6 +1369,9 @@ enum dupstring {
   STRING_PROXYPASSWORD,   /* Proxy <password>, if used */
   STRING_NOPROXY,         /* List of hosts which should not use the proxy, if
                              used */
+#if defined(HAVE_GSSAPI) || defined(USE_WINDOWS_SSPI)
+  STRING_SOCKS5_GSSAPI_SERVICE,  /* GSSAPI service name */
+#endif
 
   /* -- end of strings -- */
   STRING_LAST /* not used, just an end-of-list marker */
@@ -1524,6 +1530,9 @@ struct UserDefined {
                                via an HTTP proxy */
   char *str[STRING_LAST]; /* array of strings, pointing to allocated memory */
   unsigned int scope;    /* address scope for IPv6 */
+#if defined(HAVE_GSSAPI) || defined(USE_WINDOWS_SSPI)
+  long socks5_gssapi_nec; /* flag to support nec socks5 server */
+#endif
 };
 
 struct Names {