Thomas J. Moore provided a patch that introduces Kerberos5 support in

libcurl. This also makes the options change name to --krb (from --krb4) and
CURLOPT_KRBLEVEL (from CURLOPT_KRB4LEVEL) but the old names are still

docs/FEATURES

@@ -73,7 +73,7 @@ HTTPS (*1)
 FTP
  - download
  - authentication
- - kerberos4 (*5)
+ - kerberos4 (*5), kerberos5 (*3)
  - active/passive using PORT, EPRT, PASV or EPSV
  - single file size information (compare to HTTP HEAD)
  - 'type=' URL support

docs/MANUAL

@@ -809,18 +809,19 @@ CUSTOM OUTPUT
 
         curl -w 'We downloaded %{size_download} bytes\n' www.download.com
 
-KERBEROS4 FTP TRANSFER
+KERBEROS FTP TRANSFER
 
-  Curl supports kerberos4 for FTP transfers. You need the kerberos package
-  installed and used at curl build time for it to be used.
+  Curl supports kerberos4 and kerberos5/GSSAPI for FTP transfers. You need
+  the kerberos package installed and used at curl build time for it to be
+  used.
 
-  First, get the krb-ticket the normal way, like with the kauth tool. Then use
-  curl in way similar to:
+  First, get the krb-ticket the normal way, like with the kinit/kauth tool.
+  Then use curl in way similar to:
 
-        curl --krb4 private ftp://krb4site.com -u username:fakepwd
+        curl --krb private ftp://krb4site.com -u username:fakepwd
 
   There's no use for a password on the -u switch, but a blank one will make
-  curl ask for one and you already entered the real password to kauth.
+  curl ask for one and you already entered the real password to kinit/kauth.
 
 TELNET
 

docs/curl.1

@@ -593,13 +593,14 @@ private key is. DER, PEM and ENG are supported. If not specified, PEM is
 assumed.
 
 If this option is used several times, the last one will be used.
-.IP "--krb4 <level>"
-(FTP) Enable Kerberos4 authentication and use. The level must be entered and
+.IP "--krb <level>"
+(FTP) Enable Kerberos authentication and use. The level must be entered and
 should be one of 'clear', 'safe', 'confidential' or 'private'. Should you use
 a level that is not one of these, 'private' will instead be used.
 
-This option requires that the library was built with Kerberos4 support. This
-is not very common. Use \fI-V/--version\fP to see if your curl supports it.
+This option requires that the library was built with kerberos4 or GSSAPI
+(GSS-Negotiate) support. This is not very common. Use \fI-V/--version\fP to
+see if your curl supports it.
 
 If this option is used several times, the last one will be used.
 .IP "-K/--config <config file>"
@@ -1153,7 +1154,7 @@ Automatic decompression of compressed files over HTTP is supported.
 .IP "NTLM"
 NTLM authentication is supported.
 .IP "GSS-Negotiate"
-Negotiate authentication is supported.
+Negotiate authentication and krb5 for ftp is supported.
 .IP "Debug"
 This curl uses a libcurl built with Debug. This enables more error-tracking
 and memory debugging etc. For curl-developers only!

docs/libcurl/curl_easy_setopt.3

@@ -1370,12 +1370,12 @@ this to 1 to enable it. By default all transfers are done using the
 cache. Note that while nothing ever should get hurt by attempting to reuse SSL
 session-IDs, there seem to be broken SSL implementations in the wild that may
 require you to disable this in order for you to succeed. (Added in 7.16.0)
-.IP CURLOPT_KRB4LEVEL
-Pass a char * as parameter. Set the krb4 security level, this also enables
-krb4 awareness.  This is a string, 'clear', 'safe', 'confidential' or
-\&'private'.  If the string is set but doesn't match one of these, 'private'
-will be used. Set the string to NULL to disable Kerberos4. The Kerberos
-support only works for FTP.
+.IP CURLOPT_KRBLEVEL
+Pass a char * as parameter. Set the kerberos security level for FTP; this
+also enables kerberos awareness.  This is a string, 'clear', 'safe',
+'confidential' or \&'private'.  If the string is set but doesn't match one
+of these, 'private' will be used. Set the string to NULL to disable kerberos
+support for FTP.
 .SH SSH OPTIONS
 .IP CURLOPT_SSH_AUTH_TYPES
 Pass a long set to a bitmask consisting of one or more of