/usr/share/doc/samhain/manual.html/send-commands.html

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>Chapter 6. Configuring <SPAN
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><H1
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><A
NAME="SEND-COMMANDS"
>6.11. Sending commands to clients</A
></H1
><P
>It is generally not possible to send commands to clients, because
the client does not listen on the network (the client needs root privileges
to perform its tasks, and you don't want a root network daemon).</P
><P
>However, it is possible to send a command if and when a client
connects to deliver a message. As of version 1.8.0, clients
use a new version of the client/server protocol, which includes
a set of pre-defined commands that are understood by the client.
Currently implemented are <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>RELOAD</I
></SPAN
> to reload
the configuration, <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>SCAN</I
></SPAN
> to request a file system
check (ouside the regular schedule), and <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>STOP</I
></SPAN
> to 
terminate the client.</P
><P
>Pre-1.8.0 clients, or clients build with the (optional) old protocol
version, will simply ignore such commands.</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="SUPPLY-COMMANDS"
>6.11.1. Communicating with the server</A
></H2
><P
>As of version 1.8.0, <SPAN
CLASS="APPLICATION"
>yule</SPAN
> can send a command
to a client if and when a client connects to deliver a message, e.g. a
timestamp message (clients are not listening on the network, and thus
commands can only be sent together with the confirmation when a message
is received).</P
><P
>  
Of course the server needs to know which (if any) command to send.
Therefore it can open a unix domain socket upon startup (in the same 
directory as the PID file). Opening this command interface must be requested
explicitely with the option
<B
CLASS="COMMAND"
>SetUseSocket=<TT
CLASS="REPLACEABLE"
><I
>yes</I
></TT
></B
> (in the
[Misc] section). </P
><P
>A separate application
<SPAN
CLASS="APPLICATION"
>yulectl</SPAN
> is compiled together with the server
that provides a command-line interface to access this facility. Use
<B
CLASS="COMMAND"
>yulectl -h</B
> for help. </P
></DIV
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><H2
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><A
NAME="AUTH-CRED"
>6.11.2. Authenticating to the server</A
></H2
><P
>There are two methods to authenticate to the server.
If supported by the OS, authentication is done by 
passing the credentials of the
socket peer to the server (this is a special feature of unix domain
sockets), and <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>requiring the UID</I
></SPAN
> of the 
the socket peer (i.e. the user using the <SPAN
CLASS="APPLICATION"
>yulectl</SPAN
>
program) to match a UID as set with the 
<B
CLASS="COMMAND"
>SetSocketAllowUid=<TT
CLASS="REPLACEABLE"
><I
>UID</I
></TT
></B
> option
(default is 0, i.e. only root can use the interface). </P
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>&nbsp;</TD
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><P
>If passing credentials over the socket is supported by the OS,
it is not possible
to fake these credentials - they are supplied by the kernel.
Therefore, the server can rely on the fact that the user process
writing to the socket has indeed the UID passed via the socket. 
Thus, the access rights to the socket are basically not important (on some
systems, they are not even recognized/respected at all).</P
></TD
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></DIV
><P
>As of version 1.8.12, if (and only if) passing credentials over the socket
is not supported, you can specify a password with the
<B
CLASS="COMMAND"
>SetSocketPassword=<TT
CLASS="REPLACEABLE"
><I
>password</I
></TT
></B
> 
option. The password must be 14 characters or less, and must not include
the '@' character.</P
><P
>Of course you must supply the password to 
<SPAN
CLASS="APPLICATION"
>yulectl</SPAN
> if you want to communicate with
the server. To do so, create a file <TT
CLASS="FILENAME"
>.yulectl_cred</TT
>
in your home directory, and place the password there.</P
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>Note</B
></TH
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><TD
>&nbsp;</TD
><TD
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><P
>Password authentication is not supported if the OS supports the
aforementioned method. You can use <B
CLASS="COMMAND"
>yule -v</B
> to find
out which of the two authentication methods is supported. </P
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samhain 3.1.0-5ubuntu1 / usr / share / doc / samhain / manual.html / send-commands.html
