<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Guardian</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REL="HOME"
TITLE="PowerDNS manual"
HREF="index.html"><LINK
REL="UP"
TITLE="PDNS internals"
HREF="pdns-internals.html"><LINK
REL="PREVIOUS"
TITLE="PDNS internals"
HREF="pdns-internals.html"><LINK
REL="NEXT"
TITLE="Modules & Backends"
HREF="modules.html"></HEAD
><BODY
CLASS="SECT1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>PowerDNS manual</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="pdns-internals.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Appendix B. PDNS internals</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="modules.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="GUARDIAN"
>B.2. Guardian</A
></H1
><P
> When launched by the init.d script, <TT
CLASS="FILENAME"
>pdns_server</TT
> wraps itself inside a 'guardian'. This guardian monitors the
performance of the inner <TT
CLASS="FILENAME"
>pdns_server</TT
> instance which shows up in the process list of your OS as
<TT
CLASS="FILENAME"
>pdns_server-instance</TT
>.
It is also this guardian that <TT
CLASS="FILENAME"
>pdns_control</TT
> talks to. A <B
CLASS="COMMAND"
>STOP</B
> is interpreted by the guardian,
which causes the guardian to sever the connection to the inner process and terminate it, after which it terminates itself.
The init.d script <B
CLASS="COMMAND"
>DUMP</B
> and <B
CLASS="COMMAND"
>SHOW</B
> commands need to access the inner process, because
the guardian itself does not run a nameserver. For this purpose, the guardian passes controlsocket requests to the control console of the
inner process. This is the same console as seen with init.d <B
CLASS="COMMAND"
>MONITOR</B
>.
</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="pdns-internals.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="modules.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>PDNS internals</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="pdns-internals.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Modules & Backends</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
