Hi, Recently I'm noticing an interesting issue. My CentOS servers are trying to send logs to a logging server via 514/udp, however I'm not receiving anything. I did the following on CentOS *tcpdump -vvv -nn udp -i esn160 port 514* In another session on the same server: *nc syslog-server -u 514* tcpdump started to show me messages like: *[bad udp cksum 0x3ce9 -> 0xb0f5!] SYSLOG, length: 172* After some research I disabled TCO (ethtool -K ens160 tx off rx off), now tcpdump shows: *[udp sum ok] [|syslog]* And I'm also receiving the logs. Yay! I have the same issue on multiple servers with CentOS versions 7.3.1611, 7.4.1708 & 7.5.1804. I'm having the issue no matter if it is a physical or virtual server (they also use different hardware and NIC's) Of course I could run ethtool every time a server starts but I think there should be a better solution. Also I enjoy having TCO giving some rest to the CPUs. Did anyone find a solution for this? Thanks! Laszlo
> Hi, > > Recently I'm noticing an interesting issue. > My CentOS servers are trying to send logs to a logging server via 514/udp, > however I'm not receiving anything. > > I did the following on CentOS > *tcpdump -vvv -nn udp -i esn160 port 514* > > In another session on the same server: > *nc syslog-server -u 514* > > tcpdump started to show me messages like: > *[bad udp cksum 0x3ce9 -> 0xb0f5!] SYSLOG, length: 172* > > After some research I disabled TCO (ethtool -K ens160 tx off rx off), now > tcpdump shows: > *[udp sum ok] [|syslog]* > And I'm also receiving the logs. Yay! > > I have the same issue on multiple servers with CentOS versions 7.3.1611, > 7.4.1708 & 7.5.1804. I'm having the issue no matter if it is a physical or > virtual server (they also use different hardware and NIC's) > > Of course I could run ethtool every time a server starts but I think there > should be a better solution. Also I enjoy having TCO giving some rest to > the CPUs. > > Did anyone find a solution for this?You can configure the ETHTOOL_OPTS option in the ifcfg files to automatically assign settings on startup. Regards, Simon
I could, however that is going to increase the CPU load, mostly under heavy network load. On Fri, Aug 10, 2018 at 3:34 AM, Simon Matter <simon.matter at invoca.ch> wrote:> > Hi, > > > > Recently I'm noticing an interesting issue. > > My CentOS servers are trying to send logs to a logging server via > 514/udp, > > however I'm not receiving anything. > > > > I did the following on CentOS > > *tcpdump -vvv -nn udp -i esn160 port 514* > > > > In another session on the same server: > > *nc syslog-server -u 514* > > > > tcpdump started to show me messages like: > > *[bad udp cksum 0x3ce9 -> 0xb0f5!] SYSLOG, length: 172* > > > > After some research I disabled TCO (ethtool -K ens160 tx off rx off), now > > tcpdump shows: > > *[udp sum ok] [|syslog]* > > And I'm also receiving the logs. Yay! > > > > I have the same issue on multiple servers with CentOS versions 7.3.1611, > > 7.4.1708 & 7.5.1804. I'm having the issue no matter if it is a physical > or > > virtual server (they also use different hardware and NIC's) > > > > Of course I could run ethtool every time a server starts but I think > there > > should be a better solution. Also I enjoy having TCO giving some rest to > > the CPUs. > > > > Did anyone find a solution for this? > > You can configure the ETHTOOL_OPTS option in the ifcfg files to > automatically assign settings on startup. > > Regards, > Simon > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos >
I have seen such and issue but it depends on the environment structure. I have seen it mostly on VM's and it was resolved. The hardware and software details of the setup might help to understand what's causing it. Eliezer ---- Eliezer Croitoru Linux System Administrator Mobile: +972-5-28704261 Email: eliezer at ngtech.co.il -----Original Message----- From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of Laszlo Danielisz Sent: Thursday, August 9, 2018 9:53 PM To: centos at centos.org Subject: [CentOS] bad udp cksum Hi, Recently I'm noticing an interesting issue. My CentOS servers are trying to send logs to a logging server via 514/udp, however I'm not receiving anything. I did the following on CentOS *tcpdump -vvv -nn udp -i esn160 port 514* In another session on the same server: *nc syslog-server -u 514* tcpdump started to show me messages like: *[bad udp cksum 0x3ce9 -> 0xb0f5!] SYSLOG, length: 172* After some research I disabled TCO (ethtool -K ens160 tx off rx off), now tcpdump shows: *[udp sum ok] [|syslog]* And I'm also receiving the logs. Yay! I have the same issue on multiple servers with CentOS versions 7.3.1611, 7.4.1708 & 7.5.1804. I'm having the issue no matter if it is a physical or virtual server (they also use different hardware and NIC's) Of course I could run ethtool every time a server starts but I think there should be a better solution. Also I enjoy having TCO giving some rest to the CPUs. Did anyone find a solution for this? Thanks! Laszlo _______________________________________________ CentOS mailing list CentOS at centos.org https://lists.centos.org/mailman/listinfo/centos
Well, it is in general a good idea to disable all the fancy nic feature like tso, gro, rx/tx offload if strange things happen -----Urspr?ngliche Nachricht----- Von: CentOS <centos-bounces at centos.org> Im Auftrag von Eliezer Croitoru Gesendet: Donnerstag, 6. September 2018 13:51 An: 'CentOS mailing list' <centos at centos.org> Betreff: Re: [CentOS] bad udp cksum I have seen such and issue but it depends on the environment structure. I have seen it mostly on VM's and it was resolved. The hardware and software details of the setup might help to understand what's causing it. Eliezer ---- Eliezer Croitoru Linux System Administrator Mobile: +972-5-28704261 Email: eliezer at ngtech.co.il -----Original Message----- From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of Laszlo Danielisz Sent: Thursday, August 9, 2018 9:53 PM To: centos at centos.org Subject: [CentOS] bad udp cksum Hi, Recently I'm noticing an interesting issue. My CentOS servers are trying to send logs to a logging server via 514/udp, however I'm not receiving anything. I did the following on CentOS *tcpdump -vvv -nn udp -i esn160 port 514* In another session on the same server: *nc syslog-server -u 514* tcpdump started to show me messages like: *[bad udp cksum 0x3ce9 -> 0xb0f5!] SYSLOG, length: 172* After some research I disabled TCO (ethtool -K ens160 tx off rx off), now tcpdump shows: *[udp sum ok] [|syslog]* And I'm also receiving the logs. Yay! I have the same issue on multiple servers with CentOS versions 7.3.1611, 7.4.1708 & 7.5.1804. I'm having the issue no matter if it is a physical or virtual server (they also use different hardware and NIC's) Of course I could run ethtool every time a server starts but I think there should be a better solution. Also I enjoy having TCO giving some rest to the CPUs. Did anyone find a solution for this? Thanks! Laszlo _______________________________________________ CentOS mailing list CentOS at centos.org https://lists.centos.org/mailman/listinfo/centos _______________________________________________ CentOS mailing list CentOS at centos.org https://lists.centos.org/mailman/listinfo/centos ________________________________ financial.com AG Munich Head Office/Hauptsitz M?nchen: Georg-Muche-Stra?e 3 | 80807 Munich | Germany | Tel. +49 89 318528-0 | Google Maps: https://goo.gl/maps/UHwj9 Frankfurt Branch Office/Niederlassung Frankfurt: Messeturm | Friedrich-Ebert-Anlage 49 | 60327 Frankfurt am Main | Germany | Google Maps: https://goo.gl/maps/oSGjR Management Board/Vorstand: Dr. Steffen B?hnert | Dr. Alexis Eisenhofer | Dr. Yann Samson Supervisory Board/Aufsichtsrat: Werner Engelhardt (Chairman/Vorsitzender), Eric Wasescha (Deputy Chairman/Stellv. Vorsitzender), Franz Baur Register Court/Handelsregister: Munich ? HRB 128972 | Sales Tax ID Number/St.Nr.: DE205370553