patch-2.0.34 linux/Documentation/networking/ip_dynaddr.txt

• Lines: 58
• Date: Wed Jun 3 15:17:46 1998
• Orig file: v2.0.33/linux/Documentation/networking/ip_dynaddr.txt
• Orig date: Wed Sep 17 12:00:48 1997

diff -u --recursive --new-file v2.0.33/linux/Documentation/networking/ip_dynaddr.txt linux/Documentation/networking/ip_dynaddr.txt
@@ -1,10 +1,10 @@
-IP dynamic address hack-port v0.03
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+IP dynamic address hack-port v0.03-rst
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 This stuff allows diald ONESHOT connections to get established by
 dynamically changing packet source address (and socket's if local procs).
 It is implemented for TCP diald-box connections(1) and IP_MASQuerading(2).
 
-If enabled[*] and forwarding interface has changed:
+If enabled[*] and forwarding interface address has changed:
   1)  Socket (and packet) source address is rewritten ON RETRANSMISSIONS
       while in SYN_SENT state (diald-box processes).
   2)  Out-bounded MASQueraded source address changes ON OUTPUT (when
@@ -16,14 +16,39 @@
 going up. So, the *same* (local AND masqueraded) connections requests that
 bring the link up will be able to get established.
 
+If you enable the RST-provoking mode, then the source address will
+be changed, even if the socket is established. This means we send
+an incorrect packet out, which causes the remote host to kill our
+socket. This is the desired behaviour, because such a socket is
+doomed anyway, and the earlier it dies, the better.  This prevents
+the dial-on-demand connection from being kept up by a dead connection,
+and tells the application that the connection was lost.
+
 [*] At boot, by default no address rewriting is attempted. 
-  To enable:
+
+The values for the ip_dynaddr sysctl are:
+
+  1:  To enable:
+  2:  To enable verbosity:
+  4:  To enable RST-provoking:
+
+Flags can be combined by adding them. Common settings
+would be:
+
+  To switch off special handling of dynamic addresses (default)
+     # echo 0 > /proc/sys/net/ipv4/ip_dynaddr
+  To enable rewriting in quiet mode:
      # echo 1 > /proc/sys/net/ipv4/ip_dynaddr
-  To enable verbose mode:
+  To enable rewriting in verbose mode:
+     # echo 3 > /proc/sys/net/ipv4/ip_dynaddr
+  (for backwards compatibility you can also use)
      # echo 2 > /proc/sys/net/ipv4/ip_dynaddr
-  To disable (default)
-     # echo 0 > /proc/sys/net/ipv4/ip_dynaddr
+  To enable quiet RST-provoking mode:
+     # echo 5 > /proc/sys/net/ipv4/ip_dynaddr
+  To enable verbose RST-provoking mode:
+     # echo 7 > /proc/sys/net/ipv4/ip_dynaddr
 
 Enjoy!
 
 -- Juanjo  <jjciarla@raiz.uncu.edu.ar>
+(with RST-provoking mode by Erik Corry <erik@arbat.com>)