---
name: "shishi_realm_for_server_dns"
section: "3"
platform: "linux"
package: "shishi-doc"
version: "1.0.3-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/shishi_realm_for_server_dns"
---

# shishi\_realm\_for\_server\_dns(3)

API function

## NAME

shishi\_realm\_for\_server\_dns - API function

## SYNOPSIS

**#include \<shishi.h\>**

**char \* shishi\_realm\_for\_server\_dns(Shishi \*** *handle***, char \*** *server***);**

## ARGUMENTS

- Shishi \* handle

  Shishi library handle created by **shishi\_init()**.

- char \* server

  Hostname to find realm for.

## DESCRIPTION

Finds the realm for a host *server* using DNS lookup, as is prescribed in "draft-ietf-krb-wg-krb-dns-locate-03.txt".

Since DNS lookup can 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 trust across multiple realms the attack may redirect you to a compromised realm. For this reason, Shishi prints a warning, suggesting that the user should instead add a proper 'server-realm' configuration token.

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 for

\_kerberos.foo.asdf.com.  IN TXT

Finding no match, it would then query for

\_kerberos.asdf.com.      IN TXT

With the resource records stated above, the latter query returns a positive answer.

## RETURN VALUE

Returns realm for the indicated host, or **NULL** if no relevant TXT record could be found.

## REPORTING BUGS

Report bugs to \<bug-shishi@gnu.org\>. GNU Shishi home page: http://www.gnu.org/software/shishi/ General help using GNU software: http://www.gnu.org/gethelp/

## COPYRIGHT

Copyright © 2002-2022 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.

## SEE ALSO

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.