This bug is missing log files that will aid in diagnosing the problem. >From a terminal window please run:
apport-collect 1388786 and then change the status of the bug to 'Confirmed'. If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'. This change has been made by an automated script, maintained by the Ubuntu Kernel Team. ** Changed in: linux (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1388786 Title: TCP stale transfer with erroneous SACK information Status in “linux” package in Ubuntu: Incomplete Bug description: Cisco PIX/FWSM changes TCP sequence numbers but doesn't change numbers in SACK TCP options. When this erroneous information comes to Linux server there is some corruption in TCP stack in some circunstances with CUBIC TCP congestion algorithm and transfer stales. Problem can be reproduced in Ubuntu Server 14.04 when a Cisco FWSM is changing sequence numbers (default configuration) and a big file (30MB, for example) is being transfered. Can be solved deactivating SACK: sysctl -w net.ipv4.tcp_sack=0 We have solved it also with this configuration: sysctl -w net.ipv4.tcp_congestion_control=reno sysctl -w net.ipv4.tcp_frto=1 sysctl -w net.ipv4.tcp_early_retrans=1 We can also fix it by changing firewall configuration. Find attached a wireshark capture where you can see at 16613 frame how client requests segment 853521869 and server (158.42.250.128) resends again a previous segment for 87 seconds until it stops transfer. Thanks To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1388786/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp