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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>6.1. pam_access - logdaemon style login access control</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="Linux-PAM_SAG.html" title="The Linux-PAM System Administrators' Guide"><link rel="up" href="sag-module-reference.html" title="Chapter 6. A reference guide for available modules"><link rel="prev" href="sag-module-reference.html" title="Chapter 6. A reference guide for available modules"><link rel="next" href="sag-pam_cracklib.html" title="6.2. pam_cracklib - checks the password against dictionary words"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6.1. pam_access - logdaemon style login access control</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="sag-module-reference.html">Prev</a> </td><th width="60%" align="center">Chapter 6. A reference guide for available modules</th><td width="20%" align="right"> <a accesskey="n" href="sag-pam_cracklib.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sag-pam_access"></a>6.1. pam_access - logdaemon style login access control</h2></div></div></div><div class="cmdsynopsis"><p><code class="command">pam_access.so</code> [
debug
] [
nodefgroup
] [
noaudit
] [
accessfile=<em class="replaceable"><code>file</code></em>
] [
fieldsep=<em class="replaceable"><code>sep</code></em>
] [
listsep=<em class="replaceable"><code>sep</code></em>
]</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_access-description"></a>6.1.1. DESCRIPTION</h3></div></div></div><p>
The pam_access PAM module is mainly for access management.
It provides logdaemon style login access control based on login
names, host or domain names, internet addresses or network numbers,
or on terminal line names, X <code class="varname">$DISPLAY</code> values,
or PAM service names in case of non-networked logins.
</p><p>
By default rules for access management are taken from config file
<code class="filename">/etc/security/access.conf</code> if you don't specify
another file.
Then individual <code class="filename">*.conf</code> files from the
<code class="filename">/etc/security/access.d/</code> directory are read.
The files are parsed one after another in the order of the system locale.
The effect of the individual files is the same as if all the files were
concatenated together in the order of parsing. This means that once
a pattern is matched in some file no further files are parsed.
If a config file is explicitly specified with the <code class="option">accessfile</code>
option the files in the above directory are not parsed.
</p><p>
If Linux PAM is compiled with audit support the module will report
when it denies access based on origin (host, tty, etc.).
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-access.conf-description"></a>6.1.2. DESCRIPTION</h3></div></div></div><p>
The <code class="filename">/etc/security/access.conf</code> file specifies
(<em class="replaceable"><code>user/group</code></em>, <em class="replaceable"><code>host</code></em>),
(<em class="replaceable"><code>user/group</code></em>, <em class="replaceable"><code>network/netmask</code></em>),
(<em class="replaceable"><code>user/group</code></em>, <em class="replaceable"><code>tty</code></em>),
(<em class="replaceable"><code>user/group</code></em>,
<em class="replaceable"><code>X-$DISPLAY-value</code></em>), or
(<em class="replaceable"><code>user/group</code></em>,
<em class="replaceable"><code>pam-service-name</code></em>)
combinations for which a login will be either accepted or refused.
</p><p>
When someone logs in, the file <code class="filename">access.conf</code> is
scanned for the first entry that matches the
(<em class="replaceable"><code>user/group</code></em>, <em class="replaceable"><code>host</code></em>) or
(<em class="replaceable"><code>user/group</code></em>, <em class="replaceable"><code>network/netmask</code></em>)
combination, or, in case of non-networked logins, the first entry
that matches the
(<em class="replaceable"><code>user/group</code></em>, <em class="replaceable"><code>tty</code></em>)
combination, or in the case of non-networked logins without a
tty, the first entry that matches the
(<em class="replaceable"><code>user/group</code></em>,
<em class="replaceable"><code>X-$DISPLAY-value</code></em>) or
(<em class="replaceable"><code>user/group</code></em>,
<em class="replaceable"><code>pam-service-name/</code></em>)
combination. The permissions field of that table entry
determines
whether the login will be accepted or refused.
</p><p>
Each line of the login access control table has three fields separated
by a ":" character (colon):
</p><p>
<em class="replaceable"><code>permission</code></em>:<em class="replaceable"><code>users/groups</code></em>:<em class="replaceable"><code>origins</code></em>
</p><p>
The first field, the <em class="replaceable"><code>permission</code></em> field, can be either a
"<span class="emphasis"><em>+</em></span>" character (plus) for access granted or a
"<span class="emphasis"><em>-</em></span>" character (minus) for access denied.
</p><p>
The second field, the
<em class="replaceable"><code>users</code></em>/<em class="replaceable"><code>group</code></em>
field, should be a list of one or more login names, group names, or
<span class="emphasis"><em>ALL</em></span> (which always matches). To differentiate
user entries from group entries, group entries should be written
with brackets, e.g. <span class="emphasis"><em>(group)</em></span>.
</p><p>
The third field, the <em class="replaceable"><code>origins</code></em>
field, should be a list of one or more tty names (for non-networked
logins), X <code class="varname">$DISPLAY</code> 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), <span class="emphasis"><em>ALL</em></span> (which always matches)
or <span class="emphasis"><em>LOCAL</em></span>. The <span class="emphasis"><em>LOCAL</em></span>
keyword matches if and only if
<span class="citerefentry"><span class="refentrytitle">pam_get_item</span>(3)</span>,
when called with an <em class="parameter"><code>item_type</code></em> of
<span class="emphasis"><em>PAM_RHOST</em></span>, returns <code class="code">NULL</code> or an
empty string (and therefore the
<em class="replaceable"><code>origins</code></em> field is compared against the
return value of
<span class="citerefentry"><span class="refentrytitle">pam_get_item</span>(3)</span>
called with an <em class="parameter"><code>item_type</code></em> of
<span class="emphasis"><em>PAM_TTY</em></span> or, absent that,
<span class="emphasis"><em>PAM_SERVICE</em></span>).
</p><p>
If supported by the system you can use
<span class="emphasis"><em>@netgroupname</em></span> in host or user patterns. The
<span class="emphasis"><em>@@netgroupname</em></span> 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.
</p><p>
The <em class="replaceable"><code>EXCEPT</code></em> operator makes it possible to
write very compact rules.
</p><p>
If the <code class="option">nodefgroup</code> 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.
</p><p>
The "<span class="emphasis"><em>#</em></span>" character at start of line (no space
at front) can be used to mark this line as a comment line.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_access-options"></a>6.1.3. OPTIONS</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">
<code class="option">accessfile=<em class="replaceable"><code>/path/to/access.conf</code></em></code>
</span></dt><dd><p>
Indicate an alternative <code class="filename">access.conf</code>
style configuration file to override the default. This can
be useful when different services need different access lists.
</p></dd><dt><span class="term">
<code class="option">debug</code>
</span></dt><dd><p>
A lot of debug information is printed with
<span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span>.
</p></dd><dt><span class="term">
<code class="option">noaudit</code>
</span></dt><dd><p>
Do not report logins from disallowed hosts and ttys to the audit subsystem.
</p></dd><dt><span class="term">
<code class="option">fieldsep=<em class="replaceable"><code>separators</code></em></code>
</span></dt><dd><p>
This option modifies the field separator character that
pam_access will recognize when parsing the access
configuration file. For example:
<span class="emphasis"><em>fieldsep=|</em></span> will cause the
default `:' character to be treated as part of a field value
and `|' becomes the field separator. Doing this may be
useful in conjunction with a system that wants to use
pam_access with X based applications, since the
<span class="emphasis"><em>PAM_TTY</em></span> item is likely to be
of the form "hostname:0" which includes a `:' character in
its value. But you should not need this.
</p></dd><dt><span class="term">
<code class="option">listsep=<em class="replaceable"><code>separators</code></em></code>
</span></dt><dd><p>
This option modifies the list separator character that
pam_access will recognize when parsing the access
configuration file. For example:
<span class="emphasis"><em>listsep=,</em></span> will cause the
default ` ' (space) and `\t' (tab) characters to be treated
as part of a list element value and `,' becomes the only
list element separator. Doing this may be useful on a system
with group information obtained from a Windows domain,
where the default built-in groups "Domain Users",
"Domain Admins" contain a space.
</p></dd><dt><span class="term">
<code class="option">nodefgroup</code>
</span></dt><dd><p>
User tokens which are not enclosed in parentheses will not be
matched against the group database. The backwards compatible default is
to try the group database match even for tokens not enclosed
in parentheses.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_access-types"></a>6.1.4. MODULE TYPES PROVIDED</h3></div></div></div><p>
All module types (<code class="option">auth</code>, <code class="option">account</code>,
<code class="option">password</code> and <code class="option">session</code>) are provided.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_access-return_values"></a>6.1.5. RETURN VALUES</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">PAM_SUCCESS</span></dt><dd><p>
Access was granted.
</p></dd><dt><span class="term">PAM_PERM_DENIED</span></dt><dd><p>
Access was not granted.
</p></dd><dt><span class="term">PAM_IGNORE</span></dt><dd><p>
<code class="function">pam_setcred</code> was called which does nothing.
</p></dd><dt><span class="term">PAM_ABORT</span></dt><dd><p>
Not all relevant data or options could be gotten.
</p></dd><dt><span class="term">PAM_USER_UNKNOWN</span></dt><dd><p>
The user is not known to the system.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_access-files"></a>6.1.6. FILES</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="filename">/etc/security/access.conf</code></span></dt><dd><p>Default configuration file</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-access.conf-examples"></a>6.1.7. EXAMPLES</h3></div></div></div><p>
These are some example lines which might be specified in
<code class="filename">/etc/security/access.conf</code>.
</p><p>
User <span class="emphasis"><em>root</em></span> should be allowed to get access via
<span class="emphasis"><em>cron</em></span>, X11 terminal <span class="emphasis"><em>:0</em></span>,
<span class="emphasis"><em>tty1</em></span>, ..., <span class="emphasis"><em>tty5</em></span>,
<span class="emphasis"><em>tty6</em></span>.
</p><p>+:root:crond :0 tty1 tty2 tty3 tty4 tty5 tty6</p><p>
User <span class="emphasis"><em>root</em></span> 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.
</p><p>+:root:192.168.200.1 192.168.200.4 192.168.200.9</p><p>+:root:127.0.0.1</p><p>
User <span class="emphasis"><em>root</em></span> should get access from network
<code class="literal">192.168.201.</code> where the term will be evaluated by
string matching. But it might be better to use network/netmask instead.
The same meaning of <code class="literal">192.168.201.</code> is
<span class="emphasis"><em>192.168.201.0/24</em></span> or
<span class="emphasis"><em>192.168.201.0/255.255.255.0</em></span>.
</p><p>+:root:192.168.201.</p><p>
User <span class="emphasis"><em>root</em></span> should be able to have access from hosts
<span class="emphasis"><em>foo1.bar.org</em></span> and <span class="emphasis"><em>foo2.bar.org</em></span>
(uses string matching also).
</p><p>+:root:foo1.bar.org foo2.bar.org</p><p>
User <span class="emphasis"><em>root</em></span> should be able to have access from
domain <span class="emphasis"><em>foo.bar.org</em></span> (uses string matching also).
</p><p>+:root:.foo.bar.org</p><p>
User <span class="emphasis"><em>root</em></span> should be denied to get access
from all other sources.
</p><p>-:root:ALL</p><p>
User <span class="emphasis"><em>foo</em></span> and members of netgroup
<span class="emphasis"><em>admins</em></span> should be allowed to get access
from all sources. This will only work if netgroup service is available.
</p><p>+:@admins foo:ALL</p><p>
User <span class="emphasis"><em>john</em></span> and <span class="emphasis"><em>foo</em></span>
should get access from IPv6 host address.
</p><p>+:john foo:2001:db8:0:101::1</p><p>
User <span class="emphasis"><em>john</em></span> should get access from IPv6 net/mask.
</p><p>+:john:2001:db8:0:101::/64</p><p>
Disallow console logins to all but the shutdown, sync and all
other accounts, which are a member of the wheel group.
</p><p>-:ALL EXCEPT (wheel) shutdown sync:LOCAL</p><p>
All other users should be denied to get access from all sources.
</p><p>-:ALL:ALL</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_access-authors"></a>6.1.8. AUTHORS</h3></div></div></div><p>
The logdaemon style login access control scheme was designed and implemented by
Wietse Venema.
The pam_access PAM module was developed by
Alexei Nogin <alexei@nogin.dnttm.ru>.
The IPv6 support and the network(address) / netmask feature
was developed and provided by Mike Becher <mike.becher@lrz-muenchen.de>.
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