apport information ** Tags added: apport-collected trusty
** Description changed: We have observed the following behaviour on our LVS systems, which is causing issues with our monitor scripts. The systems are running Ubuntu 14.04.5 LTS and I've tested both with the stock 3.13.0 kernel (-100 and -116) and the 4.4.0-72 xenial kernel. Our systems are set up in direct routing mode for the services they handle. Our monitor scripts for DNS send test queries to our DNS servers using their real IPs. Sporadically, we have seen these checks fail as the DNS answers are coming back from the wrong IP address. We debugged this using tcpdump, and found that the response packets coming into the LVS systems were using the correct IPs (i.e. the real IPs on the DNS servers). However, applications see the responses as coming from a VIP instead. All of this has been established using UDP traffic. I have tracked this behaviour down to a specific case, which I can only assume is associated with how the kernel handles LVS NAT connections (i.e. masquerade mode): - If a DNS query is made on the LVS server to a DNS VIP, that creates an entry in the connection table, and is keyed on (srcip:sport -> dstip:dport) and associated with (vip:vport) - for example, (lvsip:50000 -> dnsip:53) associated with (dnsvip:53) - If a subsequent DNS query is made from the same UDP port, the response is correct as seen by tcpdump - When the response is seen by the application, the source IP address for the response is wrong I have inferred that as the response comes back from dnsip:53 and there is a connection table entry, IPVS seems to assume NAT is in use, and translates it using the entry (lvsip:50000 -> dnsip:53). The application layer then sees the response from (dnsvip:53), which is incorrect. /proc/version_signature (from both nodes): Ubuntu 3.13.0-100.147-generic 3.13.11-ckt39 Ubuntu 4.4.0-72.93~14.04.1-generic 4.4.49 IPVS Configuration: root@lvs5:~# ipvsadm -Sn -A -t 144.32.128.183:25 -s wlc -a -t 144.32.128.183:25 -r 144.32.129.29:25 -g -w 10 -a -t 144.32.128.183:25 -r 144.32.129.64:25 -g -w 10 -A -t 144.32.128.183:465 -s wlc -a -t 144.32.128.183:465 -r 144.32.129.29:465 -g -w 10 -a -t 144.32.128.183:465 -r 144.32.129.64:465 -g -w 10 -A -t 144.32.128.183:587 -s wlc -a -t 144.32.128.183:587 -r 144.32.129.29:587 -g -w 10 -a -t 144.32.128.183:587 -r 144.32.129.64:587 -g -w 10 -A -t 144.32.128.240:53 -s rr -a -t 144.32.128.240:53 -r 144.32.128.227:53 -g -w 10 -A -t 144.32.128.242:53 -s rr -a -t 144.32.128.242:53 -r 144.32.128.143:53 -g -w 10 -A -t 144.32.129.39:25 -s wlc -a -t 144.32.129.39:25 -r 144.32.129.163:25 -g -w 10 -a -t 144.32.129.39:25 -r 144.32.129.164:25 -g -w 10 -A -t 144.32.129.39:465 -s wlc -a -t 144.32.129.39:465 -r 144.32.129.163:465 -g -w 10 -a -t 144.32.129.39:465 -r 144.32.129.164:465 -g -w 10 -A -t 144.32.129.39:587 -s wlc -a -t 144.32.129.39:587 -r 144.32.129.163:587 -g -w 10 -a -t 144.32.129.39:587 -r 144.32.129.164:587 -g -w 10 -A -u 144.32.128.240:53 -s rr -a -u 144.32.128.240:53 -r 144.32.128.227:53 -g -w 10 -A -u 144.32.128.242:53 -s rr -a -u 144.32.128.242:53 -r 144.32.128.143:53 -g -w 10 + --- + AlsaDevices: + total 0 + crw-rw---- 1 root audio 116, 1 Apr 11 13:18 seq + crw-rw---- 1 root audio 116, 33 Apr 11 13:18 timer + AplayDevices: Error: [Errno 2] No such file or directory + ApportVersion: 2.14.1-0ubuntu3.23 + Architecture: amd64 + ArecordDevices: Error: [Errno 2] No such file or directory + AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: + CRDA: Error: [Errno 2] No such file or directory + DistroRelease: Ubuntu 14.04 + HibernationDevice: RESUME=/dev/mapper/lvs5--vg-swap + IwConfig: Error: [Errno 2] No such file or directory + Lsusb: + Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub + Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub + Bus 001 Device 003: ID 413c:a001 Dell Computer Corp. Hub + Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub + Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub + MachineType: Dell Inc. PowerEdge R320 + Package: linux (not installed) + PciMultimedia: + + ProcFB: 0 VESA VGA + ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-72-generic root=/dev/mapper/hostname--vg-root ro quiet splash vt.handoff=7 + ProcVersionSignature: Ubuntu 4.4.0-72.93~14.04.1-generic 4.4.49 + RelatedPackageVersions: + linux-restricted-modules-4.4.0-72-generic N/A + linux-backports-modules-4.4.0-72-generic N/A + linux-firmware 1.127.23 + RfKill: Error: [Errno 2] No such file or directory + Tags: trusty + Uname: Linux 4.4.0-72-generic x86_64 + UpgradeStatus: No upgrade log present (probably fresh install) + UserGroups: btcats daemon dba named oinstall yimsora + _MarkForUpload: True + dmi.bios.date: 01/29/2015 + dmi.bios.vendor: Dell Inc. + dmi.bios.version: 2.4.2 + dmi.board.name: 0KM5PX + dmi.board.vendor: Dell Inc. + dmi.board.version: A02 + dmi.chassis.type: 23 + dmi.chassis.vendor: Dell Inc. + dmi.modalias: dmi:bvnDellInc.:bvr2.4.2:bd01/29/2015:svnDellInc.:pnPowerEdgeR320:pvr:rvnDellInc.:rn0KM5PX:rvrA02:cvnDellInc.:ct23:cvr: + dmi.product.name: PowerEdge R320 + dmi.sys.vendor: Dell Inc. ** Attachment added: "BootDmesg.txt" https://bugs.launchpad.net/bugs/1681847/+attachment/4860191/+files/BootDmesg.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1681847 Title: IPVS incorrectly reverse-NATs traffic to LVS host To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1681847/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
