modules/pam_access/access.conf.5.xml - master - githubmirror/linux-pam

modules/pam_access/access.conf.5.xml
264 строки10 KB
Thorsten Kukuk
pam_access: rework resolving of tokens as hostname
19 ноя 2024, 01:09
19 ноя 2024, 01:09940747f
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml: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 xml: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, uid, gid, 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> or <emphasis>(gid)</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 when the user connects without a network
      connection (e.g., <emphasis>su</emphasis>,
      <emphasis>login</emphasis>). A connection through the loopback
      device (e.g., <command>ssh user@localhost</command>) is
      considered a network connection, and thus, the
      <emphasis>LOCAL</emphasis> keyword does not match.
    </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 xml: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>
      A user with uid <emphasis>1003</emphasis> and a group with gid
      <emphasis>1000</emphasis> should be allowed to get access
      from all other sources.
    </para>
    <para>+:(1000) 1003: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> and <emphasis>foo</emphasis>
      should get access from IPv6 link local host address.
    </para>
    <para>+:john foo:fe80::de95:818c:1b55:7e42%eth1</para>

    <para>
      User <emphasis>john</emphasis> should get access from IPv6 net/mask.
    </para>
    <para>+:john:2001:db8:0:101::/64</para>

    <para>
      Members of group <emphasis>wheel</emphasis> should be allowed to get access
      from all sources.
    </para>
    <para>+:(wheel):ALL</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 xml: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>
    <para>
      An IPv6 link local host address must contain the interface
      identifier. IPv6 link local network/netmask is not supported.
    </para>
    <para>
      Hostnames should be written as Fully-Qualified Host Name (FQHN) to avoid
      confusion with device names or PAM service names.
    </para>
  </refsect1>

  <refsect1 xml: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 xml: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 &lt;mike.becher@lrz-muenchen.de&gt;.
    </para>
  </refsect1>
</refentry>