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.\" $Id: kdc.8,v 1.23.2.1 2003/10/21 20:06:01 lha Exp $
.\"
.Dd October 21, 2003
.Dt KDC 8
.Os HEIMDAL
.Sh NAME
.Nm kdc
.Nd Kerberos 5 server
.Sh SYNOPSIS
.Nm
.Oo Fl c Ar file \*(Ba Xo
.Fl -config-file= Ns Ar file
.Xc
.Oc
.Op Fl p | Fl -no-require-preauth
.Op Fl -max-request= Ns Ar size
.Op Fl H | Fl -enable-http
.Op Fl -no-524
.Op Fl -kerberos4
.Op Fl -kerberos4-cross-realm
.Oo Fl r Ar string \*(Ba Xo
.Fl -v4-realm= Ns Ar string
.Xc
.Oc
.Op Fl K | Fl -kaserver
.Oo Fl P Ar portspec \*(Ba Xo
.Fl -ports= Ns Ar portspec
.Xc
.Oc
.Op Fl -detach
.Op Fl -addresses= Ns Ar list of addresses
.Sh DESCRIPTION
.Nm
serves requests for tickets.
When it starts, it first checks the flags passed, any options that are
not specified with a command line flag are taken from a config file,
or from a default compiled-in value.
.Pp
Options supported:
.Bl -tag -width Ds
.It Xo
.Fl c Ar file ,
.Fl -config-file= Ns Ar file
.Xc
Specifies the location of the config file, the default is
.Pa /var/heimdal/kdc.conf .
This is the only value that can't be specified in the config file.
.It Xo
.Fl p ,
.Fl -no-require-preauth
.Xc
Turn off the requirement for pre-autentication in the initial AS-REQ
for all principals.
The use of pre-authentication makes it more difficult to do offline
password attacks.
You might want to turn it off if you have clients
that don't support pre-authentication.
Since the version 4 protocol doesn't support any pre-authentication,
serving version 4 clients is just about the same as not requiring
pre-athentication.
The default is to require pre-authentication.
Adding the require-preauth per principal is a more flexible way of
handling this.
.It Xo
.Fl -max-request= Ns Ar size
.Xc
Gives an upper limit on the size of the requests that the kdc is
willing to handle.
.It Xo
.Fl H ,
.Fl -enable-http
.Xc
Makes the kdc listen on port 80 and handle requests encapsulated in HTTP.
.It Xo
.Fl -no-524
.Xc
don't respond to 524 requests
.It Xo
.Fl -kerberos4
.Xc
respond to Kerberos 4 requests
.It Xo
.Fl -kerberos4-cross-realm
.Xc
respond to Kerberos 4 requests from foreign realms.
This is a known security hole and should not be enabled unless you
understand the consequences and are willing to live with them.
.It Xo
.Fl r Ar string ,
.Fl -v4-realm= Ns Ar string
.Xc
What realm this server should act as when dealing with version 4
requests.
The database can contain any number of realms, but since the version 4
protocol doesn't contain a realm for the server, it must be explicitly
specified.
The default is whatever is returned by
.Fn krb_get_lrealm .
This option is only availabe if the KDC has been compiled with version
4 support.
.It Xo
.Fl K ,
.Fl -kaserver
.Xc
Enable kaserver emulation (in case it's compiled in).
.It Xo
.Fl P Ar portspec ,
.Fl -ports= Ns Ar portspec
.Xc
Specifies the set of ports the KDC should listen on.
It is given as a
white-space separated list of services or port numbers.
.It Fl -addresses= Ns Ar list of addresses
The list of addresses to listen for requests on.
By default, the kdc will listen on all the locally configured
addresses.
If only a subset is desired, or the automatic detection fails, this
option might be used.
.El
.Pp
All activities are logged to one or more destinations, see
.Xr krb5.conf 5 ,
and
.Xr krb5_openlog 3 .
The entity used for logging is
.Nm kdc .
.Sh CONFIGURATION FILE
The configuration file has the same syntax as 
.Xr krb5.conf 5 ,
but will be read before 
.Pa /etc/krb5.conf ,
so it may override settings found there.
Options specific to the KDC only are found in the
.Dq [kdc] 
section.
All the command-line options can preferably be added in the
configuration file.
The only difference is the pre-authentication flag, which has to be
specified as:
.Pp
.Dl require-preauth = no
.Pp
(in fact you can specify the option as
.Fl -require-preauth=no ) .
.Pp
And there are some configuration options which do not have
command-line equivalents:
.Bl -tag -width "xxx" -offset indent
.It Li check-ticket-addresses = Va boolean
Check the addresses in the ticket when processing TGS requests.
The default is FALSE.
.It Li allow-null-ticket-addresses = Va boolean
Permit tickets with no addresses.
This option is only relevant when check-ticket-addresses is TRUE.
.It Li allow-anonymous = Va boolean
Permit anonymous tickets with no addresses.
.It Li enforce-transited-policy = Va boolean
Always verify the transited policy, ignoring the
.Va disable-transited-check 
flag if set in the KDC client request.
.It encode_as_rep_as_tgs_rep = Va boolean
Encode AS-Rep as TGS-Rep to be bug-compatible with old DCE code.
The Heimdal clients allow both.
.It kdc_warn_pwexpire = Va time
How long before password/principal expiration the KDC should start
sending out warning messages.
.El
.Pp
The configuration file is only read when the 
.Nm
is started.
If changes made to the configuration file are to take effect, the
.Nm
needs to be restarted.
.Pp
An example of a config file:
.Bd -literal -offset indent
[kdc]
	require-preauth = no
	v4-realm = FOO.SE
	key-file = /key-file
.Ed
.Sh BUGS
If the machine running the KDC has new addresses added to it, the KDC
will have to be restarted to listen to them.
The reason it doesn't just listen to wildcarded (like INADDR_ANY)
addresses, is that the replies has to come from the same address they
were sent to, and most OS:es doesn't pass this information to the
application.
If your normal mode of operation require that you add and remove
addresses, the best option is probably to listen to a wildcarded TCP
socket, and make sure your clients use TCP to connect.
For instance, this will listen to IPv4 TCP port 88 only:
.Bd -literal -offset indent
kdc --addresses=0.0.0.0 --ports="88/tcp" 
.Ed
.Pp
There should be a way to specify protocol, port, and address triplets,
not just addresses and protocol, port tuples.
.Sh SEE ALSO
.Xr kinit 1 ,
.Xr krb5.conf 5