Ubuntu Manpage: saslauthd — sasl authentication server

Provided by: sasl2-bin_2.1.28+dfsg1-5ubuntu3.1_amd64

NAME

     saslauthd — sasl authentication server

SYNOPSIS

     saslauthd -a authmech [-Tvdchlr] [-O option] [-m mux_path] [-n threads] [-s size] [-t timeout]

DESCRIPTION

saslauthd is a daemon process that handles plaintext authentication requests on behalf of the SASL library.

The server fulfills two roles: it isolates all code requiring superuser privileges into a single process,
and it can be used to provide proxy authentication services to clients that do not understand SASL based
authentication.

saslauthd should be started from the system boot scripts when going to multi-user mode. When running
against a protected authentication database (e.g. the 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 systemd(1)
:

1. create directory /etc/systemd/system/saslauthd.service.d/
2. create file /etc/systemd/system/saslauthd.service.d/user.conf with content

[Service]
User=saslauth
Group=saslauth

3. Reload systemd service file: run “systemctl daemon-reload”

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 AUTHENTICATION MECHANISMS section.

-a authmech
Use authmech as the authentication mechanism. (See the AUTHENTICATION MECHANISMS section below.)
This parameter is mandatory.

-O option
A mechanism specific option (e.g. rimap hostname or config file path)

-H hostname
The remote host to be contacted by the rimap authentication mechanism. (Deprecated, use -O instead)

-m path
Use 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.

-n threads
Use 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.

-s size
Use size as the table size of the hash table (in kilobytes)

-t timeout
Use timeout as the expiration time of the authentication cache (in seconds)

-T Honour time-of-day login restrictions.

-h Show usage information

-c Enable caching of authentication credentials

-l Disable the use of a lock file for controlling access to accept().

-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 getpwent, this is the only way to authenticate domain-specific
users sharing the same userid.

-v Print the version number and available authentication mechanisms on standard error, then exit.

-d Debugging mode.

Logging
saslauthd logs its activities via syslogd using the LOG_AUTH facility.

AUTHENTICATION MECHANISMS

saslauthd supports one or more "authentication mechanisms", dependent upon the facilities provided by the
underlying operating system. The mechanism is selected by the -a flag from the following list of choices:

dce (AIX)

Authenticate using the DCE authentication environment.

getpwent (All platforms)

Authenticate using the getpwent() library function. Typically this authenticates against the
local password file. See your system's getpwent(3) man page for details.

kerberos4 (All platforms)

Authenticate against the local Kerberos 4 realm. (See the NOTES section for caveats about this
driver.)

kerberos5 (All platforms)

Authenticate against the local Kerberos 5 realm.

pam (Linux, Solaris)

Authenticate using Pluggable Authentication Modules (PAM).

rimap (All platforms)

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 ‘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 ‘LOGIN’ command is received from the remote server.

The option parameter to the -O flag describes the remote server to forward authentication
requests to. 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
‘imap’ service port. A non-default port can be specified by appending a slash and the port name
or number to the hostname argument.

The -O flag and argument are mandatory when using the rimap mechanism.

shadow (AIX, Irix, Linux, Solaris)

Authenticate against the local "shadow password file". The exact mechanism is system dependent.
saslauthd currently understands the getspnam() and getuserpw() library routines. Some systems
honour the -T flag.

sasldb (All platforms)

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.

ldap (All platforms that support OpenLDAP 2.0 or higher)

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.

sia (Digital UNIX)

Authenticate using the Digital UNIX Security Integration Architecture (a.k.a. "enhanced
security").

NOTES

     The kerberos4 authentication driver consumes considerable resources. To perform an authentication it must
     obtain a ticket granting ticket from the TGT server 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 saslauthd ,
     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.)

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