kerberos Kerberos 5 reference implementation from MIT This option enables Kerberos V4 backwards compatibility using the builtin Kerberos V4 library. This is really outdated and dangerous to use because not safe. Creates and installs the API and implementation documentation. This is only useful if you want to develop software which depends on kerberos. Some of the unit-tests in the build tree rely upon using a program in Tcl. This flag is marked for removal. Enables ipv6 support which is default in actual releases. This flag is marked for removal.