From 72b40d872ba61f7542b97600d8169528e5e9357c Mon Sep 17 00:00:00 2001 From: Trevor Daniels Date: Wed, 3 Mar 2010 00:39:11 +0000 Subject: [PATCH] Docs: CG 2.4.6 Add warning about MTU in domestic router --- Documentation/contributor/source-code.itexi | 25 +++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/Documentation/contributor/source-code.itexi b/Documentation/contributor/source-code.itexi index b27228d2f3..27e30b165a 100644 --- a/Documentation/contributor/source-code.itexi +++ b/Documentation/contributor/source-code.itexi @@ -1452,6 +1452,31 @@ should add these lines to @file{.git/config}: @end example @end itemize +@knownissues +Encryption protocols, including ssh, generally do not permit packet +fragmentation to avoid introducing a point of insecurity. This +means that the maximum packet size must not exceed the smallest +MTU (Maximum Transmission Unit) set in the routers along the path. +This smallest MTU is determined by a procedure during call set-up +which relies on the transmission over the path of ICMP packets. +If any of the routers in the path block ICMP packets this mechanism +fails, resulting in the possibility of packets being transmitted +which exceed the MTU of one of the routers. If this happens the +packet is discarded, causing the ssh session to hang, timeout or +terminate with the error message + +@example +ssh: connect to host port 22: Bad file number +fatal: The remote end hung up unexpectedly +@end example + +depending on precisely when in the proceedings the first large +packet is transmitted. Most routers on the internet have MTU +set to 1500, but routers installed in homes to connect via +broadband may use a slightly smaller MTU for efficient transmission +over ATM. If this problem is encountered a possible work-around is +to set the MTU in the local router to 1500. + @node Git on Windows @section Git on Windows -- 2.39.5