"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">

<refentry id="access.conf">

  <refmeta>

    <refentrytitle>access.conf</refentrytitle>

    <manvolnum>5</manvolnum>

    <refmiscinfo class="sectdesc">Linux-PAM Manual</refmiscinfo>

  </refmeta>

  <refnamediv>

    <refname>access.conf</refname>

    <refpurpose>the login access control table file</refpurpose>

  </refnamediv>

  <refsect1 id='access.conf-description'>

    <title>DESCRIPTION</title>

    <para>

      The <filename>/etc/security/access.conf</filename> file specifies

      (<replaceable>user/group</replaceable>, <replaceable>host</replaceable>),

      (<replaceable>user/group</replaceable>, <replaceable>network/netmask</replaceable>),

      (<replaceable>user/group</replaceable>, <replaceable>tty</replaceable>),

      (<replaceable>user/group</replaceable>,

      <replaceable>X-$DISPLAY-value</replaceable>), or

      (<replaceable>user/group</replaceable>,

      <replaceable>pam-service-name</replaceable>)

      combinations for which a login will be either accepted or refused.

    </para>

    <para>

      When someone logs in, the file <filename>access.conf</filename> is

      scanned for the first entry that matches the

      (<replaceable>user/group</replaceable>, <replaceable>host</replaceable>) or

      (<replaceable>user/group</replaceable>, <replaceable>network/netmask</replaceable>)

      combination, or, in case of non-networked logins, the first entry

      that matches the

      (<replaceable>user/group</replaceable>, <replaceable>tty</replaceable>)

      combination, or in the case of non-networked logins without a

      tty, the first entry that matches the

      (<replaceable>user/group</replaceable>,

      <replaceable>X-$DISPLAY-value</replaceable>) or

      (<replaceable>user/group</replaceable>,

      <replaceable>pam-service-name/</replaceable>)

      combination.  The permissions field of that table entry

      determines

      whether the login will be accepted or refused.

   </para>

    <para>

      Each line of the login access control table has three fields separated

      by a ":" character (colon):

    </para>

    <para>

      <replaceable>permission</replaceable>:<replaceable>users/groups</replaceable>:<replaceable>origins</replaceable>

    </para>

    <para>

      The first field, the <replaceable>permission</replaceable> field, can be either a

      "<emphasis>+</emphasis>" character (plus) for access granted or a

      "<emphasis>-</emphasis>" character (minus) for access denied.

    </para>

    <para>

      The second field, the

      <replaceable>users</replaceable>/<replaceable>group</replaceable>

      field, should be a list of one or more login names, group names, or

      <emphasis>ALL</emphasis> (which always matches). To differentiate

      user entries from group entries, group entries should be written

      with brackets, e.g. <emphasis>(group)</emphasis>.

    </para>

    <para>

      The third field, the <replaceable>origins</replaceable>

      field, should be a list of one or more tty names (for non-networked

      logins), X <varname>$DISPLAY</varname> values or PAM service

      names (for non-networked logins without a tty), host names,

      domain names (begin with "."), host addresses,

      internet network numbers (end with "."), internet network addresses

      with network mask (where network mask can be a decimal number or an

      internet address also), <emphasis>ALL</emphasis> (which always matches)

      or <emphasis>LOCAL</emphasis>. The <emphasis>LOCAL</emphasis>

      keyword matches if and only if

      <citerefentry><refentrytitle>pam_get_item</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

      when called with an <parameter>item_type</parameter> of

      <emphasis>PAM_RHOST</emphasis>, returns NULL or an

      empty string (and therefore the

      <replaceable>origins</replaceable> field is compared against the

      return value of

      <citerefentry><refentrytitle>pam_get_item</refentrytitle><manvolnum>3</manvolnum></citerefentry>

      called with an <parameter>item_type</parameter> of

      <emphasis>PAM_TTY</emphasis> or, absent that,

      <emphasis>PAM_SERVICE</emphasis>).

    </para>

    <para>

      If supported by the system you can use

      <emphasis>@netgroupname</emphasis> in host or user patterns. The

      <emphasis>@@netgroupname</emphasis> syntax is supported in the user

      pattern only and it makes the local system hostname to be passed

      to the netgroup match call in addition to the user name. This might not

      work correctly on some libc implementations causing the match to

      always fail.

    </para>

    <para>

      The <replaceable>EXCEPT</replaceable> operator makes it possible to

      write very compact rules.

    </para>

    <para>

       If the <option>nodefgroup</option> is not set, the group file

       is searched when a name does not match that of the logged-in

       user. Only groups are matched in which users are explicitly listed.

       However the PAM module does not look at the primary group id of a user.

    </para>

    <para>

      The "<emphasis>#</emphasis>" character at start of line (no space

      at front) can be used to mark this line as a comment line.

    </para>

  </refsect1>

  <refsect1 id="access.conf-examples">

    <title>EXAMPLES</title>

    <para>

      These are some example lines which might be specified in

      <filename>/etc/security/access.conf</filename>.

    </para>

    <para>

      User <emphasis>root</emphasis> should be allowed to get access via

      <emphasis>cron</emphasis>, X11 terminal <emphasis remap='I'>:0</emphasis>,

      <emphasis>tty1</emphasis>, ..., <emphasis>tty5</emphasis>,

      <emphasis>tty6</emphasis>.

    </para>

    <para>+:root:crond :0 tty1 tty2 tty3 tty4 tty5 tty6</para>

    <para>

      User <emphasis>root</emphasis> should be allowed to get access from

      hosts which own the IPv4 addresses. This does not mean that the

      connection have to be a IPv4 one, a IPv6 connection from a host with

      one of this IPv4 addresses does work, too.

    </para>

    <para>+:root:192.168.200.1 192.168.200.4 192.168.200.9</para>

    <para>+:root:127.0.0.1</para>

    <para>

      User <emphasis>root</emphasis> should get access from network

      <literal>192.168.201.</literal> where the term will be evaluated by

      string matching. But it might be better to use network/netmask instead.

      The same meaning of <literal>192.168.201.</literal> is

      <emphasis>192.168.201.0/24</emphasis> or

      <emphasis>192.168.201.0/255.255.255.0</emphasis>.

    </para>

    <para>+:root:192.168.201.</para>

    <para>

      User <emphasis>root</emphasis> should be able to have access from hosts

      <emphasis>foo1.bar.org</emphasis> and <emphasis>foo2.bar.org</emphasis>

      (uses string matching also).

    </para>

    <para>+:root:foo1.bar.org foo2.bar.org</para>

    <para>

      User <emphasis>root</emphasis> should be able to have access from

      domain <emphasis>foo.bar.org</emphasis> (uses string matching also).

    </para>

    <para>+:root:.foo.bar.org</para>

    <para>

      User <emphasis>root</emphasis> should be denied to get access

      from all other sources.

    </para>

    <para>-:root:ALL</para>

    <para>

      User <emphasis>foo</emphasis> and members of netgroup

      <emphasis>admins</emphasis> should be allowed to get access

      from all sources. This will only work if netgroup service is available.

    </para>

    <para>+:@admins foo:ALL</para>

    <para>

      User <emphasis>john</emphasis> and <emphasis>foo</emphasis>

      should get access from IPv6 host address.

    </para>

    <para>+:john foo:2001:db8:0:101::1</para>

    <para>

      User <emphasis>john</emphasis> should get access from IPv6 net/mask.

    </para>

    <para>+:john:2001:db8:0:101::/64</para>

    <para>

      Disallow console logins to all but the shutdown, sync and all

      other accounts, which are a member of the wheel group.

    </para>

    <para>-:ALL EXCEPT (wheel) shutdown sync:LOCAL</para>

    <para>

      All other users should be denied to get access from all sources.

    </para>

    <para>-:ALL:ALL</para>

  </refsect1>

  <refsect1 id="access.conf-notes">

    <title>NOTES</title>

    <para>

      The default separators of list items in a field are space, ',', and tabulator

      characters. Thus conveniently if spaces are put at the beginning and the end of

      the fields they are ignored. However if the list separator is changed with the

      <emphasis>listsep</emphasis> option, the spaces will become part of the actual

      item and the line will be most probably ignored. For this reason, it is not

      recommended to put spaces around the ':' characters.

    </para>

  </refsect1>

  <refsect1 id="access.conf-see_also">

    <title>SEE ALSO</title>

    <para>

      <citerefentry><refentrytitle>pam_access</refentrytitle><manvolnum>8</manvolnum></citerefentry>,

      <citerefentry><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

      <citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>

    </para>

  </refsect1>

  <refsect1 id="access.conf-author">

    <title>AUTHORS</title>

    <para>

      Original <citerefentry><refentrytitle>login.access</refentrytitle><manvolnum>5</manvolnum></citerefentry>

      manual was provided by Guido van Rooij which was renamed to

      <citerefentry><refentrytitle>access.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>

      to reflect relation to default config file.

    </para>

    <para>

      Network address / netmask description and example text was

      introduced by Mike Becher <mike.becher@lrz-muenchen.de>.

    </para>

  </refsect1>

</refentry>