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<title>pamela: the pamelad internal program</title>
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<h1> The pamelad program </h1>
<p>
pamelad is a helper program spawned by the pamela library, at <tt>pam_start()</tt> time.
It communicates with the main application process, reading requests from it,
performing PAM calls, and returning results to the application process.
</p>
<h2> Interface </h2>
<p>
pamelad is not meant to be called directly. It is an <em>unexported</em>
program, i.e. a program that the package's library is supposed to find, but
that users should not run. Ideally it's kept outside of users' PATH variable.
</p>
<p>
pamelad is declared as a <em>libexec</em> binary, so it will probably be
installed in <tt>/usr/libexec/pamelad</tt> or <tt>/usr/lib/pamela/pamelad</tt>,
depending on the admin/distribution's preferences.
</p>
<p>
pamelad is run with two arguments, which are the <em>service_name</em> and
<em>user</em> arguments given to the <tt>pam_start()</tt> call. This will
display in a <tt>ps</tt> output, which is fine since this information is
not confidential.
</p>
<p>
pamelad runs as the same uid and gid as the application. However, to
increase security of applications running as root:
</p>
<ul>
<li> If the application runs as gid 0 and the PAMELA_GID environment
variable is set, then pamelad will run with a gid set to <tt>$PAMELA_GID</tt>. </li>
<li> If the application runs as uid 0 and the PAMELA_UID environment
variable is set, then pamelad will run with a uid set to <tt>$PAMELA_UID</tt>. </li>
</ul>
<p>
pamelad makes the real calls to Linux-PAM. Keep that in mind when
configuring your PAM authorizations: if you're using the PAMELA_UID and
PAMELA_GID variables, make sure the uid/gid are not used anywhere else,
and give the proper PAM authorizations to that uid/gid pair instead of root.
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