1.\" Copyright (c) 1997-2002 Kungliga Tekniska H�gskolan 2.\" $Id: krb5_425_conv_principal.3,v 1.8 2002/08/28 15:30:46 joda Exp $ 3.Dd April 11, 1999 4.Dt KRB5_425_CONV_PRINCIPAL 3 5.Os HEIMDAL 6.Sh NAME 7.Nm krb5_425_conv_principal , 8.Nm krb5_425_conv_principal_ext , 9.Nm krb5_524_conv_principal 10.Nd converts to and from version 4 principals 11.Sh LIBRARY 12Kerberos 5 Library (libkrb5, -lkrb5) 13.Sh SYNOPSIS 14.Fd #include <krb5.h> 15.Ft krb5_error_code 16.Fn krb5_425_conv_principal "krb5_context context" "const char *name" "const char *instance" "const char *realm" "krb5_principal *principal" 17.Ft krb5_error_code 18.Fn 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" 19.Ft krb5_error_code 20.Fn krb5_524_conv_principal "krb5_context context" "const krb5_principal principal" "char *name" "char *instance" "char *realm" 21.Sh DESCRIPTION 22Converting between version 4 and version 5 principals can at best be 23described as a mess. 24.Pp 25A version 4 principal consists of a name, an instance, and a realm. A 26version 5 principal consists of one or more components, and a 27realm. In some cases also the first component/name will differ between 28version 4 and version 5. Furthermore the second component of a host 29principal will be the fully qualified domain name of the host in 30question, while the instance of a version 4 principal will only 31contain the first part (short hostname). Because of these problems 32the conversion between principals will have to be site customized. 33.Pp 34.Fn krb5_425_conv_principal_ext 35will try to convert a version 4 principal, given by 36.Fa name , 37.Fa instance , 38and 39.Fa realm , 40to a version 5 principal. This can result in several possible 41principals, and if 42.Fa func 43is non-NULL, it will be called for each candidate principal. 44.Fa func 45should return true if the principal was 46.Dq good . 47To accomplish this, 48.Fn krb5_425_conv_principal_ext 49will look up the name in 50.Pa krb5.conf . 51It first looks in the 52.Li v4_name_convert/host 53subsection, which should contain a list of version 4 names whose 54instance should be treated as a hostname. This list can be specified 55for each realm (in the 56.Li realms 57section), or in the 58.Li libdefaults 59section. If the name is found the resulting name of the principal 60will be the value of this binding. The instance is then first looked 61up in 62.Li v4_instance_convert 63for the specified realm. If found the resulting value will be used as 64instance (this can be used for special cases), no further attempts 65will be made to find a conversion if this fails (with 66.Fa func ) . 67If the 68.Fa resolve 69parameter is true, the instance will be looked up with 70.Fn gethostbyname . 71This can be a time consuming, error prone, and unsafe operation. Next 72a list of hostnames will be created from the instance and the 73.Li v4_domains 74variable, which should contain a list of possible domains for the 75specific realm. 76.Pp 77On the other hand, if the name is not found in a 78.Li host 79section, it is looked up in a 80.Li v4_name_convert/plain 81binding. If found here the name will be converted, but the instance 82will be untouched. 83.Pp 84This list of default host-type conversions is compiled-in: 85.Bd -literal -offset indent 86v4_name_convert = { 87 host = { 88 ftp = ftp 89 hprop = hprop 90 imap = imap 91 pop = pop 92 rcmd = host 93 smtp = smtp 94 } 95} 96.Ed 97.Pp 98It will only be used if there isn't an entry for these names in the 99config file, so you can override these defaults. 100.Pp 101.Fn krb5_425_conv_principal 102will call 103.Fn krb5_425_conv_principal_ext 104with 105.Dv NULL 106as 107.Fa func , 108and the value of 109.Li v4_instance_resolve 110(from the 111.Li libdefaults 112section) as 113.Fa resolve . 114.Pp 115.Fn krb5_524_conv_principal 116basically does the opposite of 117.Fn krb5_425_conv_principal , 118it just doesn't have to look up any names, but will instead truncate 119instances found to belong to a host principal. The 120.Fa name , 121.Fa instance , 122and 123.Fa realm 124should be at least 40 characters long. 125.Sh EXAMPLES 126Since this is confusing an example is in place. 127.Pp 128Assume that we have the 129.Dq foo.com , 130and 131.Dq bar.com 132domains that have shared a single version 4 realm, FOO.COM. The version 4 133.Pa krb.realms 134file looked like: 135.Bd -literal -offset indent 136foo.com FOO.COM 137\&.foo.com FOO.COM 138\&.bar.com FOO.COM 139.Ed 140.Pp 141A 142.Pa krb5.conf 143file that covers this case might look like: 144.Bd -literal -offset indent 145[libdefaults] 146 v4_instance_resolve = yes 147[realms] 148 FOO.COM = { 149 kdc = kerberos.foo.com 150 v4_instance_convert = { 151 foo = foo.com 152 } 153 v4_domains = foo.com 154 } 155.Ed 156.Pp 157With this setup and the following host table: 158.Bd -literal -offset indent 159foo.com 160a-host.foo.com 161b-host.bar.com 162.Ed 163the following conversions will be made: 164.Bd -literal -offset indent 165rcmd.a-host \(-> host/a-host.foo.com 166ftp.b-host \(-> ftp/b-host.bar.com 167pop.foo \(-> pop/foo.com 168ftp.other \(-> ftp/other.foo.com 169other.a-host \(-> other/a-host 170.Ed 171.Pp 172The first three are what you expect. If you remove the 173.Dq v4_domains , 174the fourth entry will result in an error (since the host 175.Dq other 176can't be found). Even if 177.Dq a-host 178is a valid host name, the last entry will not be converted, since the 179.Dq other 180name is not known to represent a host-type principal. 181If you turn off 182.Dq v4_instance_resolve 183the second example will result in 184.Dq ftp/b-host.foo.com 185(because of the default domain). And all of this is of course only 186valid if you have working name resolving. 187.Sh SEE ALSO 188.Xr krb5_build_principal 3 , 189.Xr krb5_free_principal 3 , 190.Xr krb5_parse_name 3 , 191.Xr krb5_sname_to_principal 3 , 192.Xr krb5_unparse_name 3 , 193.Xr krb5.conf 5 194