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.Dd December 12 2005
.Dt SASLAUTHD 8
.Os "CMU-SASL"
.Sh NAME
.Nm saslauthd
.Nd sasl authentication server
.Sh SYNOPSIS
.Nm
.Fl a
.Ar authmech
.Op Fl \&Tvdchlr
.Op Fl O Ar option
.Op Fl m Ar mux_path
.Op Fl n Ar threads
.Op Fl s Ar size
.Op Fl t Ar timeout
.Sh DESCRIPTION
.Nm
is a daemon process that handles plaintext authentication requests
on behalf of the SASL library.
.Pp
The server fulfills two roles: it isolates all code requiring superuser
privileges into a single process, and it can be used to provide
.Em proxy
authentication services to clients that do not understand
SASL based authentication.
.Pp
.Nm
should be
started from the system boot scripts when going to
multi-user mode. When running against a protected authentication
database (e.g. the
.Li shadow
mechanism),
it must be run as the superuser. Otherwise it is recommended to run
daemon unprivileged as saslauth:saslauth, requiring the runtime directory
to have root:saslauthd owner. You can do so by following
these steps in machines using
.Xr systemd 1
:

.Bl -enum -compact
.It
create directory
.Pa /etc/systemd/system/saslauthd.service.d/
.It
create file
.Pa /etc/systemd/system/saslauthd.service.d/user.conf
with content
.Bd -literal
[Service]
User=saslauth
Group=saslauth

.Ed
.It
Reload systemd service file: run
.Dq systemctl daemon-reload
.El
.Ss Options
Options named by lower\-case letters configure the server itself.
Upper\-case options control the behavior of specific authentication
mechanisms; their applicability to a particular authentication
mechanism is described in the
.Sx AUTHENTICATION MECHANISMS
section.
.Bl -tag -width indent
.It Fl a Ar authmech
Use
.Ar authmech
as the authentication mechanism. (See the
.Sx AUTHENTICATION MECHANISMS
section below.) This parameter is mandatory.
.It Fl O Ar option
A mechanism specific option (e.g. rimap hostname or config file path)
.It Fl H Ar hostname
The remote host to be contacted by the
.Li rimap
authentication mechanism. (Deprecated, use -O instead)
.It Fl m Ar path
Use
.Ar path
as the pathname to the named socket to listen on for
connection requests. This must be an absolute pathname, and MUST NOT
include the trailing "/mux".  Note that the default for this value
is "/var/state/saslauthd" (or what was specified at compile time)
and that this directory must exist for saslauthd to function.
.It Fl n Ar threads
Use
.Ar threads
processes for responding to authentication queries. (default: 5)  A
value of zero will indicate that saslauthd should fork an individual
process for each connection.  This can solve leaks that occur in some
deployments.
.It Fl s Ar size
Use
.Ar size
as the table size of the hash table (in kilobytes)
.It Fl t Ar timeout
Use
.Ar timeout
as the expiration time of the authentication cache (in seconds)
.It Fl T
Honour time-of-day login restrictions.
.It Fl h
Show usage information
.It Fl c
Enable caching of authentication credentials
.It Fl l
Disable the use of a lock file for controlling access to accept().
.It Fl r
Combine the realm with the login (with an '@' sign in between).  e.g.
login: "foo" realm: "bar" will get passed as login: "foo@bar".  Note
that the realm will still be passed, which may lead to unexpected
behavior for authentication mechanisms that make use of the realm,
however for mechanisms which don't, such as
.Ar getpwent ,
this is the only way to authenticate domain-specific users sharing the
same userid.
.It Fl v
Print the version number and available authentication
mechanisms on standard error, then exit.
.It Fl d
Debugging mode.
.El
.Ss Logging
.Nm
logs its activities via
.Nm syslogd
using the
.Dv LOG_AUTH
facility.
.Sh AUTHENTICATION MECHANISMS
.Nm
supports one or more
.Qq authentication mechanisms ,
dependent upon the facilities provided by the underlying operating system.
The mechanism is selected by the
.Fl a
flag from the following list of choices:
.Bl -tag -width "kerberos4"
.It Li dce
.Em (AIX)
.Pp
Authenticate using the DCE authentication environment.
.It Li getpwent
.Em (All platforms)
.Pp
Authenticate using the
.Fn getpwent
library function. Typically this authenticates against the
local password file. See your system's
.Xr getpwent 3
man page for details.
.It Li kerberos4
.Em (All platforms)
.Pp
Authenticate against the local Kerberos 4 realm. (See the
.Sx NOTES
section for caveats about this driver.)
.It Li kerberos5
.Em (All platforms)
.Pp
Authenticate against the local Kerberos 5 realm.
.It Li pam
.Em (Linux, Solaris)
.Pp
Authenticate using Pluggable Authentication Modules (PAM).
.It Li rimap
.Em (All platforms)
.Pp
Forward authentication requests to a remote IMAP server. This driver
connects to a remote IMAP server, specified using the -O flag,
and attempts to login (via an IMAP
.Ql LOGIN
command) using the credentials 
supplied to the local
server. If the remote authentication succeeds the local connection
is also considered to be authenticated. The remote connection is closed
as soon as the tagged response from the
.Ql LOGIN
command is received from the remote
server.
.Pp
The
.Ar option
parameter to the
.Fl O
flag describes the remote server to forward
authentication requests to.
.Ar hostname
can be a hostname (imap.example.com) or a dotted\-quad IP address
(192.168.0.1). The latter is useful if the remote server is
multi\-homed and has network interfaces that are unreachable from
the local IMAP server. The remote host is contacted on the
.Ql imap
service port. A non\-default port can be specified by appending
a slash and the port name or number
to the
.Ar hostname
argument.
.Pp
The
.Fl O
flag and argument are mandatory when using the
.Li rimap
mechanism.
.It Li shadow
.Em (AIX, Irix, Linux, Solaris)
.Pp
Authenticate against the local
.Qq shadow password file .
The exact mechanism is system dependent.
.Nm
currently understands the
.Fn getspnam
and
.Fn getuserpw
library routines. Some systems
honour the
.Fl T
flag.
.It Li sasldb
.Em (All platforms)
.Pp
Authenticate against the
SASL authentication database.  Note that this is probably not what you
want to use, and is even disabled at compile-time by default.
If you want to use sasldb with the SASL library, you probably want to
use the pwcheck_method of "auxprop" along with the sasldb auxprop plugin
instead.
.It Li ldap
.Em (All platforms that support OpenLDAP 2.0 or higher)
.Pp
Authenticate against an ldap server.  The ldap configuration parameters are
read from /etc/saslauthd.conf.  The location of this file can be
changed with the -O parameter. See the LDAP_SASLAUTHD file included in the
cyrus-sasl2-doc package for the list of available parameters.
.It Li sia
.Em (Digital UNIX)
.Pp
Authenticate using the Digital
.Ux
Security Integration Architecture
(a.k.a.
.Qq enhanced security ) .
.El
.Sh NOTES
The
.Li kerberos4
authentication driver consumes considerable resources. To perform an
authentication it must obtain a ticket granting ticket
from the TGT server
.Sy on every authentication request.
The Kerberos library routines that obtain the TGT also create a
local ticket file, on the reasonable assumption that you will want
to save the TGT for use by other Kerberos applications. These ticket
files are unusable by
.Nm No ,
however there is no way not to create them. The overhead of creating
and removing
these ticket files can cause serious performance degradation on busy
servers. (Kerberos
was never intended to be used in this manner, anyway.)
.Sh FILES
.Bl -tag -width "/var/run/saslauthd/mux"
.It Pa /var/run/saslauthd/mux
The default communications socket.
.It Pa /etc/saslauthd.conf
The default configuration file for ldap support.
.El
.Sh SEE ALSO
.Xr passwd 1 ,
.Xr getpwent 3 ,
.Xr getspnam 3 ,
.Xr getuserpw 3 ,
.Xr sasl_checkpass 3
.Xr sia_authenticate_user 3 ,