SYNOPSIS

#include <shishi.h>

char * shishi_realm_for_server_dns(Shishi * handle, char * server);

ARGUMENTS

Shishi * handle

Shishi library handle create by shishi_init().

char * server

hostname to find realm for.

DESCRIPTION

Find realm for a host using DNS lookups, according to draft-ietf-krb-wg-krb-dns-locate-03.txt. Since DNS lookups may be spoofed, relying on the realm information may result in a redirection attack. In a single-realm scenario, this only achieves a denial of service, but with cross-realm trust it may redirect you to a compromised realm. For this reason, Shishi prints a warning, suggesting that the user should add the proper 'server-realm' configuration tokens instead.

To illustrate the DNS information used, here is an extract from a zone file for the domain ASDF.COM:

_kerberos.asdf.com. IN TXT "ASDF.COM" _kerberos.mrkserver.asdf.com. IN TXT "MARKETING.ASDF.COM" _kerberos.salesserver.asdf.com. IN TXT "SALES.ASDF.COM"

Let us suppose that in this case, a client wishes to use a service on the host foo.asdf.com. It would first query:

_kerberos.foo.asdf.com. IN TXT

Finding no match, it would then query:

_kerberos.asdf.com. IN TXT

RETURN VALUE

Returns realm for host, or NULL if not found.

REPORTING BUGS

Report bugs to <[email protected]>.

COPYRIGHT

Copyright © 2002-2010 Simon Josefsson.

Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

RELATED TO shishi_realm_for_server_dns…

The full documentation for shishi is maintained as a Texinfo manual. If the info and shishi programs are properly installed at your site, the command

  • info shishi

should give you access to the complete manual.