X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/01fe3d80cb9ebc8eefa8003cc852ec469fd87b24..dc08d858e78fc5c55c4bb1975b5df4b2db12d869:/doc/config.but

diff --git a/doc/config.but b/doc/config.but
index 7572a779..86102030 100644
--- a/doc/config.but
+++ b/doc/config.but
@@ -1,4 +1,4 @@
-\versionid $Id: config.but,v 1.83 2004/06/15 11:31:30 jacob Exp $
+\versionid $Id: config.but,v 1.86 2004/07/22 11:18:08 jacob Exp $
 
 \C{config} Configuring PuTTY
 
@@ -1447,8 +1447,9 @@ badly to the default value.
 
 The format is a pair of numbers separated by a comma, for instance,
 \c{38400,38400}. The first number represents the output speed
-(\e{from} the server), and the second is the input speed (\e{to} the
-server). (Only the first is used in the Rlogin protocol.)
+(\e{from} the server) in bits per second, and the second is the input
+speed (\e{to} the server). (Only the first is used in the Rlogin
+protocol.)
 
 This option has no effect on Raw connections.
 
@@ -1506,7 +1507,8 @@ what \e{kind} of network problems you have between you and the
 server.
 
 Keepalives are only supported in Telnet and SSH; the Rlogin and Raw
-protocols offer no way of implementing them.
+protocols offer no way of implementing them. (For an alternative, see
+\k{config-tcp-keepalives}.)
 
 Note that if you are using SSH1 and the server has a bug that makes
 it unable to deal with SSH1 ignore messages (see
@@ -1525,6 +1527,34 @@ types of server.
 
 The Nagle algorithm is disabled by default.
 
+\S{config-tcp-keepalives} \q{Enable TCP keepalives}
+
+\cfg{winhelp-topic}{connection.tcpkeepalive}
+
+\e{NOTE:} TCP keepalives should not be confused with the
+application-level keepalives described in \k{config-keepalive}. If in
+doubt, you probably want application-level keepalives; TCP keepalives
+are provided for completeness.
+
+The idea of TCP keepalives is similar to application-level keepalives,
+and the same caveats apply. The main differences are:
+
+\b TCP keepalives are available on \e{all} connection types, including
+Raw and Rlogin.
+
+\b The interval between TCP keepalives is usually much longer,
+typically two hours; this is set by the operating system, and cannot
+be configured within PuTTY.
+
+\b If the operating system does not receive a response to a keepalive,
+it may send out more in quick succession and if terminate the connection
+if no response is received.
+
+TCP keepalives may be more useful for ensuring that half-open connections
+are terminated than for keeping a connection alive.
+
+TCP keepalives are disabled by default.
+
 \H{config-proxy} The Proxy panel
 
 \cfg{winhelp-topic}{proxy.main}