Linuxguy123 wrote: > On Tue, 2010-02-09 at 11:25 +0800, Ed Greshko wrote: > > >> That is starting to stir the synapse.... >> >> The problem is related to what is in the "syn, ack" packet coming from >> 12.17.249.39. In the TCP Options it is sending "Window scale: 0 >> (multiply by 1)". I think this is causing problems since later packets >> have the TCP data segment being only 92 bytes from 12.17.249.39. >> >> While the same info is in the "syn, ack" the RHELv4 system seems to deal >> with it OK and the TCP data segments from 12.17.249.39 are 1460 bytes. >> >> The "problem" can be fixed by.... >> >> echo 0 > /proc/sys/net/ipv4/tcp_window_scaling >> >> Now, while this fixes the problem for this site it may cause performance >> issues with other sites. I don't know at this point and my head hurts. >> :-) It is hurting since my RHELv4 system has tcp_window_scaling set to >> 1 and it seems to deal with it. >> > > >> Note: Make sure you issue the "echo" above after some quite time. The >> connection must first be rst (reset) before the sides will renegotiate >> the TCP/IP settings. (That too caused me some grief.) >> > > Questions: > > a) does an "echo 1 /proc/sys/net/ipv4/tcp_window_scaling" put the system > back to what it is now ? > Yes. You can "cat /proc/sys/net/ipv4/tcp_window_scaling" to see it is set to "1" by default. > $cat /proc/sys/net/ipv4/tcp_window_scaling > 1 > > b) does the command have to be issued after every reboot / login ? > It is defaulted to "1" at boot. So, if you want to have it set to "0" you'll either have to issue the echo command or place the following in /etc/sysctl.conf net.ipv4.tcp_window_scaling = 0 (you need the spaces). > c) please tell us more on resetting the network connection. > > Nothing needs to be done to reset the connection. It will do so after a time of inactivity between your system and the affected web site. (The resets are per connection). So, if you just visited the site with scaling set to 1 you should wait a couple of minutes after setting it to 0 before trying again. Ed
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