Options for Cyrus SASL

Options for Cyrus SASL

This document contains information on what options are used by the Cyrus SASL library and bundled mechanisms. The most commonly used options (and those that are therefore most commonly misunderstood are pwcheck_method and auxprop_plugin. Please ensure that you have configured these correctly if things don't seem to be working right. Additionally, mech_list can be an easy way to limit what mechanisms a given application will use.

OptionUsed ByDescriptionDefault
authdaemond_pathSASL Library Path to Courier-IMAP authdaemond's unix socket. Only applicable when pwcheck_method is set to authdaemond./dev/null
auto_transitionSASL Library When set to 'yes' or 'noplain', and when using an auxprop plugin, automatically transition users to other mechs when they do a successful plaintext authentication. When set to 'noplain', only non-plaintext secrets will be written. Note that the only mechs (as currently implemented) which don't use plaintext secrets are OTP and SRP.no
auxprop_pluginAuxiliary Property Plugin Name of auxiliary plugin to use, you may specify a space-separated list of plugin names, and the plugins will be queried in order (null) - querys all plugins
canon_user_pluginSASL Library Name of canon_user plugin to useINTERNAL
keytabGSSAPI Location of keytab file/etc/krb5.keytab (system dependant)
ldapdb_uriLDAPDB plugin ldap server uri, you can specify a space-separated list of URIs - ldapi:// or ldaps://ldap1/ ldaps://ldap2/ none
ldapdb_idLDAPDB plugin ldap SASL authentication id none
ldapdb_mechLDAPDB plugin ldap SASL mechanism for authentication none
ldapdb_pwLDAPDB plugin ldap password for SASL authentication id none
ldapdb_rcLDAPDB plugin The filename specified here will be put into the server's LDAPRC environment variable, and libldap-specific config options may be set in that ldaprc file. The main purpose behind this option is to allow a client TLS certificate to be configured, so that SASL/EXTERNAL may be used between the SASL server and the LDAP server. This is the most optimal way to use this plugin when the servers are on separate machines. none
ldapdb_starttlsLDAPDB plugin Use StartTLS. This option may be set to 'try' or 'demand'. When set to "try" any failure in StartTLS is ignored. When set to "demand" then any failure aborts the connection. none
log_levelSASL Library Numeric Logging Level (see SASL_LOG_* in sasl.h for values and descriptions 1 (SASL_LOG_ERR)
mech_listSASL Library Whitespace separated list of mechanisms to allow (e.g. 'plain otp'). Used to restrict the mechanisms to a subset of the installed plugins.(use all available plugins)
ntlm_serverNTLM (server) Name of server (WinNT, Win2K, Samba, etc) to which authentication will be proxied. (null) - perform authentication internally
ntlm_v2NTLM (client) Send NTLMv2 responses to the server. no (send NTLMv1)
opiekeysOTP (with OPIE) Location of the opiekeys file/etc/opiekeys
otp_mdaOTP (w/o OPIE) Message digest algorithm for one-time passwords, used by sasl_setpass (possible values: 'md4', 'md5', 'sha1')md5
plugin_listSASL Library Location of Plugin list (Unsupported)none
pwcheck_methodSASL Library Whitespace separated list of mechanisms used to verify passwords, used by sasl_checkpass (possible values: 'auxprop', 'saslauthd', 'pwcheck', 'authdaemond' [if compiled with --with-authdaemond]) and 'alwaystrue' [if compiled with --enable-alwaystrue]) auxprop
reauth_timeoutDIGEST-MD5 Length in time (in minutes) that authentication info will be cached for a fast reauth. A value of 0 will disable reauth. 0
saslauthd_pathSASL Library Path to saslauthd run directory (including the "/mux" named pipe) system dependant (generally won't need to be changed)
sasldb_pathsasldb plugin Path to sasldb file/etc/sasldb2 (system dependant)
sql_engineSQL plugin Name of SQL engine to use (possible values: 'mysql', 'pgsql', 'sqlite'). mysql
sql_hostnamesSQL plugin Comma separated list of SQL servers (in host[:port] format). none (engine dependent)
sql_userSQL plugin Username to use for authentication to the SQL server. none (engine dependent)
sql_passwdSQL plugin Password to use for authentication to the SQL server. none (engine dependent)
sql_databaseSQL plugin Name of the database which contains the auxiliary properties. none (engine dependent)
sql_selectSQL plugin SELECT statement to use for fetching properties. This option is required in order to use the SQL plugin. none
sql_insertSQL plugin INSERT statement to use for creating properties for new users. none
sql_updateSQL plugin UPDATE statement to use for modifying properties. none
sql_usesslSQL plugin When set to 'yes', 'on', '1' or 'true', a secure connection will be made to the SQL server. no
srp_mdaSRP Message digest algorithm for SRP calculations (possible values: 'md5', 'sha1', 'rmd160')sha1
srvtabKERBEROS_V4 Location of the srvtab file/etc/srvtab (system dependant)

Notes on SQL auxprop options

The sql_insert and sql_update options are optional and are only needed if you wish to allow the SASL library (e.g., saslpasswd2) and plugins (e.g., OTP) to write properties to the SQL server. If used, both statements MUST be provided so that properties can be added, changed and deleted. NOTE: The columns for writable properites MUST accept NULL values.

The SQL statements provided in the sql_select, sql_insert and sql_update options can contain arguments which will be substituted with the appropriate values. The valid arguments are:

%u
Username whose properties are being fetched/stored.
%p
Name of the property being fetched/stored. This could technically be anything, but SASL authentication will try userPassword and cmusaslsecretMECHNAME (where MECHNAME is the name of a SASL mechanism).
%r
Realm to which the user belongs. This could be the kerberos realm, the FQDN of the computer the SASL application is running on or whatever is after the @ on a username. (read the realm documentation).
%v
Value of the property being stored (INSERT or UPDATE only!). This could technically be anything depending on the property itself, but is generally a userPassword.
NOTE: DO NOT put quotes around the entire SQL statement, but each individual %u, %r and %v argument MUST be quoted.

Examples:

     sql_select: SELECT %p FROM user_table WHERE username = '%u' and realm = '%r'
would send the following statement to SQL for user "bovik" and the default realm for the machine "madoka.surf.org.uk":
     SELECT userPassword FROM user_table WHERE username = 'bovik' and
     realm = 'madoka.surf.org.uk';


     sql_insert: INSERT INTO user_table (username, realm, %p) VALUES ('%u', '%r', '%v')

would generate the following statement to SQL for user "bovik" in realm "madoka.surf.org.uk" with userPassword "wert":
     INSERT INTO user_table (username, realm, userPassword) VALUES
     ('bovik', 'madoka.surf.org.uk', 'wert');


Note that all substitutions do not have to be used. For instance,

     SELECT password FROM auth WHERE username = '%u'
is a valid value for sql_select.

Notes on LDAPDB auxprop options

Unlike other LDAP-enabled plugins for other services that are common on the web, this plugin does not require you to configure DN search patterns to map usernames to LDAP DNs. This plugin requires SASL name mapping to be configured on the target slapd. This approach keeps the LDAP-specific configuration details in one place, the slapd.conf, and makes the configuration of remote services much simpler.

This plugin is not for use with slapd itself. When OpenLDAP is built with SASL support, slapd uses its own internal auxprop module. By default, without configuring anything else, slapd will fail to load the ldapdb module when it's present. This is as it should be. If you don't like the "auxpropfunc: error -7" message that is sent to syslog by slapd, you can stop it by creating /usr/lib/sasl2/slapd.conf with:

auxprop_plugin: slapd
which will force the SASL library to ignore all other auxprop modules.

Examples:

ldapdb_uri: ldap://ldap.example.com
ldapdb_id: root
ldapdb_pw: secret
ldapdb_mech: DIGEST-MD5

The LDAP server must be configured to map the SASL authcId "root" into a DN that has proxy authorization privileges to every account that is allowed to login to this server. (See the OpenLDAP Admin Guide section 10 for details.)

ldapdb_uri: ldapi://
ldapdb_mech: EXTERNAL

This configuration assumes an LDAP server is on the same server that is using SASL and the underlying OS is *NIX based (ldapi:// requires UNIX domain sockets). This is fast and secure, and needs no username or password to be stored. The slapd.conf will need to map these usernames to LDAP DNs:

sasl-regexp uidNumber=(.*)\\+gidNumber=(.*),cn=peercred,cn=external,cn=auth
    ldap:///dc=example,dc=com??sub?(&(uidNumber=$1)(gidNumber=$2))
sasl-regexp uid=(.*),cn=external,cn=auth
    ldap:///dc=example,dc=com??sub?(uid=$1)


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