Networking Change Causes Distribution Headaches Nov 10, 2008, 02 :03 UTC (3 Talkback[s]) (6429 reads) (Other stories by Jake Edge)
"The problem stems from changes that were made to clean up the TCP option code that were merged back in July as part of the 2.6.27 merge window. TCP options are a mechanism to expand the functionality of the protocol as conditions change. There are a handful of commonly used options that the two endpoints of a connection can agree to use, for things like maximum segment size (MSS), window scaling, selective acknowledgment (SACK), and timestamps. Options have been added over time to provide more internet robustness and performance as well as to support higher-bandwidth physical connections.
"A perfectly reasonable, if unintended, consequence of the code change was that the the options were put into the header in a slightly different order. According to the relevant RFCs, options can appear in any order in the option section of the TCP header. But, some home and/or internet routers seem to expect a fixed order; refusing to make connections if the order is "wrong". In particular, it would seem that the MSS option needs to appear before the SACK option."
