manual update

[l2tpns.git] / Docs / manual.html

diff --git a/Docs/manual.html b/Docs/manual.html
index 13748a9..f8f3908 100644 (file)
--- a/Docs/manual.html
+++ b/Docs/manual.html
@@ -60,8 +60,8 @@ H3 {
 </OL>
 
 <H2 ID="Overview">Overview</H2>
 </OL>
 
 <H2 ID="Overview">Overview</H2>

-l2tpns is half of a complete L2TP implementation.  It supports only the
-LNS side of the connection.<P>
+l2tpns a complete L2TP implementation. It supports the LAC, LNS and
+ PPPOE server.<P>

 
 L2TP (Layer 2 Tunneling Protocol) is designed to allow any layer 2
 protocol (e.g. Ethernet, PPP) to be tunneled over an IP connection.  l2tpns
 
 L2TP (Layer 2 Tunneling Protocol) is designed to allow any layer 2
 protocol (e.g. Ethernet, PPP) to be tunneled over an IP connection.  l2tpns


@@ -184,6 +184,18 @@ the same as the LAC, or authentication will fail.  Only actually be
 used if the LAC requests authentication.
 </LI>
 
 used if the LAC requests authentication.
 </LI>
 

+<LI><B>l2tp_mtu</B> (int)<BR>
+MTU of interface for L2TP traffic (default: 1500).  Used to set link
+MRU and adjust TCP MSS.
+</LI>
+
+<LI><B>ppp_restart_time</B> (int)<BR>
+<B>ppp_max_configure</B> (int)<BR>
+<B>ppp_max_failure</B> (int)<BR>
+PPP counter and timer values, as described in &sect;4.1 of
+<a href="ftp://ftp.rfc-editor.org/in-notes/rfc1661.txt">RFC1661</a>.
+</LI>
+

 <LI><B>primary_dns</B> (ip address)
 <LI><B>secondary_dns</B> (ip address)<BR>
 Whenever a PPP connection is established, DNS servers will be sent to the
 <LI><B>primary_dns</B> (ip address)
 <LI><B>secondary_dns</B> (ip address)<BR>
 Whenever a PPP connection is established, DNS servers will be sent to the


@@ -191,14 +203,6 @@ user, both a primary and a secondary.  If either is set to 0.0.0.0, then that
 one will not be sent.
 </LI>
 
 one will not be sent.
 </LI>
 

-<LI><B>save_state</B> (boolean)<BR>
-When l2tpns receives a STGTERM it will write out its current
-ip_address_pool, session and tunnel tables to disk prior to exiting to
-be re-loaded at startup.  The validity of this data is obviously quite
-short and the intent is to allow an sessions to be retained over a
-software upgrade.
-</LI>
-

 <LI><B>primary_radius</B> (ip address)
 <LI><B>secondary_radius</B> (ip address)<BR>
 Sets the RADIUS servers used for both authentication and accounting. 
 <LI><B>primary_radius</B> (ip address)
 <LI><B>secondary_radius</B> (ip address)<BR>
 Sets the RADIUS servers used for both authentication and accounting. 


@@ -231,16 +235,43 @@ This secret will be used in all RADIUS queries.  If this is not set then
 RADIUS queries will fail.
 </LI>
 
 RADIUS queries will fail.
 </LI>
 

+<LI><B>radius_authtypes</B> (string)</BR>
+A comma separated list of supported RADIUS authentication methods
+(<B>pap</B> or <B>chap</B>), in order of preference (default <B>pap</B>).
+</LI>
+
+<LI><B>radius_dae_port</B> (short)<BR>
+Port for DAE RADIUS (Packet of Death/Disconnect, Change of Authorization)
+requests (default: <B>3799</B>).
+</LI>
+
+<LI><B>allow_duplicate_users</B> (boolean)</BR>
+Allow multiple logins with the same username.  If false (the default),
+any prior session with the same username will be dropped when a new
+session is established.
+</LI>
+

 <LI><B>bind_address</B> (ip address)<BR>
 <LI><B>bind_address</B> (ip address)<BR>

-When the tun interface is created, it is assigned the address
-specified here.  If no address is given, 1.1.1.1 is used.  Packets
-containing user traffic should be routed via this address if given,
-otherwise the primary address of the machine.
+It's the listen address of the l2tp udp protocol sent and received
+to LAC. This address is also assigned to the tun interface if no
+iftun_address is specified. Packets containing user traffic should be
+routed via this address if given, otherwise the primary address of the
+machine.
+</LI>
+
+<LI><B>iftun_address</B> (ip address)<BR>
+This parameter is used when you want a tun interface address different
+from the address of "bind_address" (For use in cases of specific configuration).
+If no address is given to iftun_address and bind_address, 1.1.1.1 is used.
+</LI>
+
+<LI><B>tundevicename</B> (string)<BR>
+Name of the tun interface (default: "tun0").

 </LI>
 
 <LI><B>peer_address</B> (ip address)<BR>
 Address to send to clients as the default gateway.
 </LI>
 
 <LI><B>peer_address</B> (ip address)<BR>
 Address to send to clients as the default gateway.

-</L1>
+</LI>

 
 <LI><B>send_garp</B> (boolean)<BR>
 Determines whether or not to send a gratuitous ARP for the
 
 <LI><B>send_garp</B> (boolean)<BR>
 Determines whether or not to send a gratuitous ARP for the


@@ -282,10 +313,6 @@ second.  Even if this is disabled, you can see this information by running
 the <EM>uptime</EM> command on the CLI.
 </LI>
 
 the <EM>uptime</EM> command on the CLI.
 </LI>
 

-<LI><B>cleanup_interval</B> (int)<BR>
-Interval between regular cleanups (in seconds).
-</LI>
-

 <LI><B>multi_read_count</B> (int)<BR>
 Number of packets to read off each of the UDP and TUN fds when
 returned as readable by select (default:  10).  Avoids incurring the
 <LI><B>multi_read_count</B> (int)<BR>
 Number of packets to read off each of the UDP and TUN fds when
 returned as readable by select (default:  10).  Avoids incurring the


@@ -307,6 +334,13 @@ Keep all pages mapped by the l2tpns process in memory.
 Maximum number of host unreachable ICMP packets to send per second.
 </LI>
 
 Maximum number of host unreachable ICMP packets to send per second.
 </LI>
 

+<LI><B>packet_limit</B> (int><BR>
+Maximum number of packets of downstream traffic to be handled each
+tenth of a second per session.  If zero, no limit is applied (default: 
+0).  Intended as a DoS prevention mechanism and not a general
+throttling control (packets are dropped, not queued).
+</LI>
+

 <LI><B>cluster_address</B> (ip address)<BR>
 Multicast cluster address (default:  239.192.13.13).  See the section
 on <A HREF="#Clustering">Clustering</A> for more information.
 <LI><B>cluster_address</B> (ip address)<BR>
 Multicast cluster address (default:  239.192.13.13).  See the section
 on <A HREF="#Clustering">Clustering</A> for more information.


@@ -316,6 +350,10 @@ on <A HREF="#Clustering">Clustering</A> for more information.
 Interface for cluster packets (default: eth0).
 </LI>
 
 Interface for cluster packets (default: eth0).
 </LI>
 

+<LI><B>cluster_mcast_ttl</B> (int)<BR>
+TTL for multicast packets (default: 1).
+</LI>
+

 <LI><B>cluster_hb_interval</B> (int)<BR>
 Interval in tenths of a second between cluster heartbeat/pings.
 </LI>
 <LI><B>cluster_hb_interval</B> (int)<BR>
 Interval in tenths of a second between cluster heartbeat/pings.
 </LI>


@@ -325,8 +363,89 @@ Cluster heartbeat timeout in tenths of a second.  A new master will be
 elected when this interval has been passed without seeing a heartbeat
 from the master.
 </LI>
 elected when this interval has been passed without seeing a heartbeat
 from the master.
 </LI>

+
+<LI><B>cluster_master_min_adv</B> (int)<BR>
+Determines the minumum number of up to date slaves required before the
+master will drop routes (default: 1).
+</LI>
+
+<LI><B>echo_timeout</B> (int)<BR>
+Time between last packet sent and LCP ECHO generation
+(default: 10 (seconds)).
+</LI>
+
+<LI><B>idle_echo_timeout</B> (int)<BR>
+Drop sessions who have not responded within idle_echo_timeout seconds
+(default: 240 (seconds))
+</LI>
+
+<LI><B>auth_tunnel_change_addr_src</B> (boolean)<BR>
+This parameter authorize to change the source IP of the tunnels l2tp.
+This parameter can be used when the remotes BAS/LAC are l2tpns server
+configured in cluster mode, but that the interface to remote LNS are
+not clustered (the tunnel can be coming from different source IP)
+(default: no).
+</LI>
+
+</UL>
+
+<P><U><B>LAC configuration</B></U></P>
+<UL>
+<LI><B>bind_address_remotelns</B> (ip address)<BR>
+Address of the interface to listen the remote LNS tunnels.
+If no address is given, all interfaces are listened (Any Address).
+</LI>
+
+<LI><B>bind_portremotelns</B> (short)<BR>
+Port to bind for the Remote LNS (default: 65432).
+</LI>
+
+</UL>
+
+<P>A static REMOTES LNS configuration can be entered by the command:</P>
+<DL> <DD><B>setforward</B> <I>MASK</I> <I>IP</I> <I>PORT</I> <I>SECRET</I> </DL>
+
+where <I>MASK</I> specifies the mask of users who have forwarded to
+remote LNS (ex: "/friendISP@company.com").</BR>
+where <I>IP</I> specifies the IP of the  remote LNS (ex: "66.66.66.55").</BR>
+where <I>PORT</I> specifies the L2TP Port of the remote LNS
+(Normally should be 1701) (ex: 1701).</BR>
+where <I>SECRET</I> specifies the secret password the remote LNS (ex: mysecret).</BR>
+</BR>
+The static Remote LNS configuration can be used when the friend ISP not 
+have a proxied Radius.</BR>
+If the proxied Radius is used, It will return the RADIUS attributes:</BR>
+       Tunnel-Type: 1 = L2TP</BR>
+       Tunnel-Medium-Type: 1 = IPv4</BR>
+       Tunnel-Password: 1 = "LESECRETL2TP"</BR>
+       Tunnel-Server-Endpoint: 1 = "88.xx.xx.x1"</BR>
+       Tunnel-Assignment-Id: 1 = "friendisp_lns1"</BR>
+       Tunnel-Type: 2 = L2TP</BR>
+       Tunnel-Medium-Type: 2 = IPv4</BR>
+       Tunnel-Password: 2 = "LESECRETL2TP"</BR>
+       Tunnel-Server-Endpoint: 2 = "88.xx.xx.x2"</BR>
+       Tunnel-Assignment-Id: 2 = "friendisp_lns2"</BR>    
+
+<P><U><B>PPPOE configuration</B></U></P>
+
+<UL>
+<LI><B>pppoe_if_to_bind</B> (string)<BR>
+PPPOE server interface to bind (ex: "eth0.12"), If not specified the server PPPOE is not enabled.
+For the pppoe clustering, all the interfaces PPPOE of the clusters must use the same HW address (MAC address).
+</LI>
+
+<LI><B>pppoe_service_name</B> (string)<BR>
+PPPOE service name (default: NULL).
+</LI>
+
+<LI><B>pppoe_ac_name</B> (string)<BR>
+PPPOE  access concentrator name (default: "l2tpns-pppoe").
+</LI>
+

 </UL>
 
 </UL>
 

+<P><U><B>BGP configuration</B></U></P>
+

 <P>BGP routing configuration is entered by the command:
 The routing configuration section is entered by the command
 <DL><DD><B>router bgp</B> <I>as</I></DL>
 <P>BGP routing configuration is entered by the command:
 The routing configuration section is entered by the command
 <DL><DD><B>router bgp</B> <I>as</I></DL>


@@ -360,23 +479,25 @@ define the body of the access-list.  Standard access-list syntax:
 
 Extended access-lists:
 
 
 Extended access-lists:
 

-<DL>
-  <DD>{<B>permit</B>|<B>deny</B>} <B>ip</B>
+<DIV STYLE="margin-left: 4em; text-indent: -2em">
+  <P>{<B>permit</B>|<B>deny</B>} <B>ip</B>

     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}

-    {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
-  <DD>{<B>permit</B>|<B>deny</B>} <B>udp</B>
+    {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>} [<B>fragments</B>]
+  <P>{<B>permit</B>|<B>deny</B>} <B>udp</B>

     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]

-  <DD>{<B>permit</B>|<B>deny</B>} <B>tcp</B>
+       [<B>fragments</B>]
+  <P>{<B>permit</B>|<B>deny</B>} <B>tcp</B>

     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
        [{<B>established</B>|{<B>match-any</B>|<B>match-all</B>}
     {<I>host</I>|<I>source source-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
     {<I>host</I>|<I>destination destination-wildcard</I>|<B>any</B>}
        [{<B>eq</B>|<B>neq</B>|<B>gt</B>|<B>lt</B>} <I>port</I>|<B>range</B> <I>from</I> <I>to</I>]
        [{<B>established</B>|{<B>match-any</B>|<B>match-all</B>}

-           {<B>+</B>|<B>-</B>}{<B>fin</B>|<B>syn</B>|<B>rst</B>|<B>psh</B>|<B>ack</B>|<B>urg</B>} ...]
-</DL>
+           {<B>+</B>|<B>-</B>}{<B>fin</B>|<B>syn</B>|<B>rst</B>|<B>psh</B>|<B>ack</B>|<B>urg</B>}
+           ...|<B>fragments</B>]
+</DIV>

 
 <H3 ID="users">users</H3>
 
 
 <H3 ID="users">users</H3>
 


@@ -682,16 +803,15 @@ killall -HUP l2tpns
 </PRE>
 
 The signals understood are:
 </PRE>
 
 The signals understood are:

-<UL>
-<LI>SIGHUP - Reload the config from disk and re-open log file<P></LI>
-<LI>SIGTERM / SIGINT - Shut down for a restart.  This will dump the current
-state to disk (if <EM>save_state</EM> is set to true).  Upon restart, the
-process will read this saved state to resume active sessions.<P>
-<LI>SIGQUIT - Shut down cleanly.  This will send a disconnect message for
-every active session and tunnel before shutting down.  This is a good idea
-when upgrading the code, as no sessions will be left with the remote end
-thinking they are open.</LI>
-</UL>
+<DL>
+<DT>SIGHUP</DT><DD>Reload the config from disk and re-open log file.</DD>
+<DT>SIGTERM, SIGINT</DT><DD>Stop process.  Tunnels and sessions are not
+terminated.  This signal should be used to stop l2tpns on a
+<A HREF="#Clustering">cluster node</A> where there are other machines to
+continue handling traffic.</DD>
+<DT>SIGQUIT</DT><DD>Shut down tunnels and sessions, exit process when
+complete.</DD>
+</DL>

 
 <H2 ID="Throttling">Throttling</H2>
 
 
 <H2 ID="Throttling">Throttling</H2>
 


@@ -804,14 +924,14 @@ supplied structure:
                some way.
                </TD>
                <TD>
                some way.
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-                       <LI>username</LI>
-                       <LI>password</LI>
-                       <LI>protocol (0xC023 for PAP, 0xC223 for CHAP)</LI>
-                       <LI>continue_auth - Set to 0 to stop processing authentication modules</LI>
-               </UL>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+                       <DT>username
+                       <DT>password
+                       <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
+                       <DT>continue_auth<DD>Set to 0 to stop processing authentication modules
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>post_auth</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>post_auth</B></TD>


@@ -821,16 +941,16 @@ supplied structure:
                to be accepted.
                </TD>
                <TD>
                to be accepted.
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-                       <LI>username</LI>
-                       <LI>auth_allowed - This is already set to true or
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+                       <DT>username
+                       <DT>auth_allowed<DD>This is already set to true or

                        false depending on whether authentication has been
                        allowed so far.  You can set this to 1 or 0 to force
                        false depending on whether authentication has been
                        allowed so far.  You can set this to 1 or 0 to force

-                       allow or disallow authentication</LI>
-                       <LI>protocol (0xC023 for PAP, 0xC223 for CHAP)</LI>
-               </UL>
+                       allow or disallow authentication
+                       <DT>protocol<DD>0xC023 for PAP, 0xC223 for CHAP
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_rx</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_rx</B></TD>


@@ -839,12 +959,12 @@ supplied structure:
                seriously slow down the system.</FONT>
                </TD>
                <TD>
                seriously slow down the system.</FONT>
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-                       <LI>buf - The raw packet data</LI>
-                       <LI>len - The length of buf</LI>
-               </UL>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+                       <DT>buf<DD>The raw packet data
+                       <DT>len<DD>The length of buf
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_tx</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>packet_tx</B></TD>


@@ -853,12 +973,12 @@ supplied structure:
                seriously slow down the system.</FONT>
                </TD>
                <TD>
                seriously slow down the system.</FONT>
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-                       <LI>buf - The raw packet data</LI>
-                       <LI>len - The length of buf</LI>
-               </UL>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+                       <DT>buf<DD>The raw packet data
+                       <DT>len<DD>The length of buf
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>timer</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>timer</B></TD>


@@ -867,9 +987,9 @@ supplied structure:
                you do is reentrant.
                </TD>
                <TD>
                you do is reentrant.
                </TD>
                <TD>

-               <UL>
-                       <LI>time_now - The current unix timestamp</LI>
-               </UL>
+               <DL>
+                       <DT>time_now<DD>The current unix timestamp
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>new_session</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>new_session</B></TD>


@@ -877,10 +997,10 @@ supplied structure:
                session is now ready to handle traffic.
                </TD>
                <TD>
                session is now ready to handle traffic.
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-               </UL>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>kill_session</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>kill_session</B></TD>


@@ -888,10 +1008,10 @@ supplied structure:
                This may be called multiple times for the same session.
                </TD>
                <TD>
                This may be called multiple times for the same session.
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-               </UL>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_response</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_response</B></TD>


@@ -901,12 +1021,24 @@ supplied structure:
                modules.
                </TD>
                <TD>
                modules.
                </TD>
                <TD>

-               <UL>
-                       <LI>t - Tunnel ID</LI>
-                       <LI>s - Session ID</LI>
-                       <LI>key</LI>
-                       <LI>value</LI>
-               </UL>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+                       <DT>key
+                       <DT>value
+               </DL>
+               </TD>
+       </TR>
+       <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>radius_reset</B></TD>
+               <TD>This is called whenever a RADIUS CoA request is
+               received to reset any options to default values before
+               the new values are applied.
+               </TD>
+               <TD>
+               <DL>
+                       <DT>t<DD>Tunnel
+                       <DT>s<DD>Session
+               </DL>

                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>control</B></TD>
                </TD>
        </TR>
        <TR VALIGN=TOP BGCOLOR=WHITE><TD><B>control</B></TD>


@@ -915,21 +1047,13 @@ supplied structure:
                required.
                </TD>
                <TD>
                required.
                </TD>
                <TD>

-               <UL>
-                       <LI>buf - The raw packet data</LI>
-                       <LI>l - The raw packet data length</LI>
-                       <LI>source_ip - Where the request came from</LI>
-                       <LI>source_port - Where the request came from</LI>
-                       <LI>response - Allocate a buffer and put your response in here</LI>
-                       <LI>response_length - Length of response</LI>
-                       <LI>send_response - true or false whether a response
-                       should be sent.  If you set this to true, you must
-                       allocate a response buffer.</LI>
-                       <LI>type - Type of request (see nsctl.c)</LI>
-                       <LI>id - ID of request</LI>
-                       <LI>data - I'm really not sure</LI>
-                       <LI>data_length - Length of data</LI>
-               </UL>
+               <DL>
+                       <DT>iam_master<DD>Cluster master status
+                       <DT>argc<DD>The number of arguments
+                       <DT>argv<DD>Arguments
+                       <DT>response<DD>Return value: NSCTL_RES_OK or NSCTL_RES_ERR
+                       <DT>additional<DD>Extended response text
+               </DL>

                </TD>
        </TR>
 </TABLE>
                </TD>
        </TR>
 </TABLE>