Mobile sites: Maintain multiple addresses for some peers (new feature)

[secnet.git] / README

diff --git a/README b/README
index 73679c2acd3695fd0a4377ffa4c685736cccaca2..3736b89bbf5dfe1b8f81574d098e456709058e4e 100644 (file)
--- a/README
+++ b/README
@@ -285,11 +285,12 @@ site: dict argument
   setup-retries (integer): max number of times to transmit a key negotiation
     packet [5]
   setup-timeout (integer): time between retransmissions of key negotiation
-    packets, in ms [1000]
+    packets, in ms [2000]
   wait-time (integer): after failed key setup, wait this long (in ms) before
     allowing another attempt [20000]
   renegotiate-time (integer): if we see traffic on the link after this time
-    then renegotiate another session key immediately [depends on key-lifetime]
+    then renegotiate another session key immediately (in ms)
+    [half key-lifetime, or key-lifetime minus 5 mins, whichever is longer].
   keepalive (bool): if True then attempt always to keep a valid session key.
     Not actually currently implemented. [false]
   log-events (string list): types of events to log for this site
@@ -303,7 +304,24 @@ site: dict argument
     packet-drop: whenever we throw away an outgoing packet
     dump-packets: every key setup packet we see
     errors: failure of name resolution, internal errors
+    peer-addrs: changes to sets of peer addresses (interesting for mobile peers)
     all: everything (too much!)
+  mobile (bool): if True then peer is "mobile" ie we assume it may
+    change its apparent IP address and port number without either it
+    or us being aware of the change; so, we remember the last several
+    port/addr pairs we've seen and send packets to all of them
+    (subject to a timeout).  We maintain one set of addresses for key
+    setup exchanges, and another for data traffic. Two communicating
+    peers must not each regard the other as mobile, or all the traffic
+    in each direction will be triplicated (strictly, transmitted
+    mobile-peers-max times) and anyway two peers whose public contact
+    address may suddenly change couldn't communicate reliably because
+    their contact addresses might both change at once. [false]
+  mobile-peers-max (integer): Maximum number of peer port/addr pairs we
+    remember and send to.  Must be at least 1 and no more than 5.  [3]
+  mobile-peer-expiry (integer): For "mobile" peers only, the length
+    of time (in seconds) for which we will keep sending to multiple
+    address/ports from which we have not seen incoming traffic. [120]
 
 ** transform