KRB5_425_CONV_PRINCIPAL(3) | Library Functions Manual | KRB5_425_CONV_PRINCIPAL(3) |
NAME¶
krb5_425_conv_principal, krb5_425_conv_principal_ext, krb5_524_conv_principal — converts to and from version 4 principalsLIBRARY¶
Kerberos 5 Library (libkrb5, -lkrb5)SYNOPSIS¶
#include <krb5.h> krb5_error_codekrb5_425_conv_principal(krb5_context context, const char *name, const char *instance, const char *realm, krb5_principal *principal); krb5_error_code
krb5_425_conv_principal_ext(krb5_context context, const char *name, const char *instance, const char *realm, krb5_boolean (*func)(krb5_context, krb5_principal), krb5_boolean resolve, krb5_principal *principal); krb5_error_code
krb5_524_conv_principal(krb5_context context, const krb5_principal principal, char *name, char *instance, char *realm);
DESCRIPTION¶
Converting between version 4 and version 5 principals can at best be described as a mess. A version 4 principal consists of a name, an instance, and a realm. A version 5 principal consists of one or more components, and a realm. In some cases also the first component/name will differ between version 4 and version 5. Furthermore the second component of a host principal will be the fully qualified domain name of the host in question, while the instance of a version 4 principal will only contain the first part (short hostname). Because of these problems the conversion between principals will have to be site customized. krb5_425_conv_principal_ext() will try to convert a version 4 principal, given by name, instance, and realm, to a version 5 principal. This can result in several possible principals, and if func is non-NULL, it will be called for each candidate principal. func should return true if the principal was “good”. To accomplish this, krb5_425_conv_principal_ext() will look up the name in krb5.conf. It first looks in thev4_name_convert/host
subsection, which should contain
a list of version 4 names whose instance should be treated as a hostname. This
list can be specified for each realm (in the realms
section), or in the libdefaults
section. If the name
is found the resulting name of the principal will be the value of this
binding. The instance is then first looked up in
v4_instance_convert
for the specified realm. If found
the resulting value will be used as instance (this can be used for special
cases), no further attempts will be made to find a conversion if this fails
(with func). If the resolve
parameter is true, the instance will be looked up with
gethostbyname(). This can be a time consuming, error prone,
and unsafe operation. Next a list of hostnames will be created from the
instance and the v4_domains
variable, which should
contain a list of possible domains for the specific realm.
On the other hand, if the name is not found in a host
section, it is looked up in a v4_name_convert/plain
binding. If found here the name will be converted, but the instance will be
untouched.
This list of default host-type conversions is compiled-in:
v4_name_convert = { host = { ftp = ftp hprop = hprop imap = imap pop = pop rcmd = host smtp = smtp } }
NULL
as func, and the value of
v4_instance_resolve
(from the
libdefaults
section) as resolve.
krb5_524_conv_principal() basically does the opposite of
krb5_425_conv_principal(), it just doesn't have to look up
any names, but will instead truncate instances found to belong to a host
principal. The name, instance, and
realm should be at least 40 characters long.
EXAMPLES¶
Since this is confusing an example is in place. Assume that we have the “foo.com”, and “bar.com” domains that have shared a single version 4 realm, FOO.COM. The version 4 krb.realms file looked like:foo.com FOO.COM .foo.com FOO.COM .bar.com FOO.COM
[libdefaults] v4_instance_resolve = yes [realms] FOO.COM = { kdc = kerberos.foo.com v4_instance_convert = { foo = foo.com } v4_domains = foo.com }
foo.com a-host.foo.com b-host.bar.com
rcmd.a-host -> host/a-host.foo.com ftp.b-host -> ftp/b-host.bar.com pop.foo -> pop/foo.com ftp.other -> ftp/other.foo.com other.a-host -> other/a-host
SEE ALSO¶
krb5_build_principal(3), krb5_free_principal(3), krb5_parse_name(3), krb5_sname_to_principal(3), krb5_unparse_name(3), krb5.conf(5)September 3, 2003 | HEIMDAL |