I have 5 desktop on Ubuntu 16.04 with various official kernel 4.4, 4.8, 4.10. All this desktop are connected via CIFS to a Windows Server 2008 R2 for a simple shared folder.
After some minutes of activity i got a high CIFS flood traffic between desktop and server. Many giga per desktop are transferred! CMD (on desktop): sudo tcpdump -p -s 0 port 445 EXAMPLE (This 5 lines below are in loop and repeated all the time): 12:10:14.778859 IP oracle.microsoft-ds > res3-ubuntu.35514: Flags [R.], seq 1, ack 43, win 0, length 0 12:10:14.778891 IP res3-ubuntu.35516 > oracle.microsoft-ds: Flags [S], seq 2388943218, win 29200, options [mss 1460,sackOK,TS val 11568532 ecr 0,nop,wscale 7], length 0 12:10:14.779104 IP oracle.microsoft-ds > res3-ubuntu.35516: Flags [S.], seq 1906593829, ack 2388943219, win 8192, options [mss 1460,nop,wscale 8,sackOK,TS val 172827841 ecr 11568532], length 0 12:10:14.779118 IP res3-ubuntu.35516 > oracle.microsoft-ds: Flags [.], ack 1, win 229, options [nop,nop,TS val 11568532 ecr 172827841], length 0 12:10:14.779210 IP res3-ubuntu.35516 > oracle.microsoft-ds: Flags [P.], seq 1:43, ack 1, win 229, options [nop,nop,TS val 11568532 ecr 172827841], length 42 SMB PACKET: SMBecho (REQUEST) -- 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/1686099 Title: connection flood to port 445 on mounting cifs volume under kernel Status in Linux: Confirmed Status in linux package in Ubuntu: Confirmed Bug description: This is identical to the bug reported on the Debian kernel list, only I'm running 4.4.0, not 4.[89].0 After about 15 mintues, the cifsd daemon starts flooding echo requests on port 445 to the windows server causing a constant 1MB/s load (around 10,000 packets per second) that eventually leads to system instability that forces a reboot to correct. This is repeatable and as far as I know started about a week ago (possibly with the installation of 4.4.0-75). https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=856843 To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1686099/+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
