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@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@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

-----Ursprüngliche Nachricht----- Von: CentOS centos-bounces@centos.org Im Auftrag von Eliezer Croitoru Gesendet: Donnerstag, 6. September 2018 13:51 An: 'CentOS mailing list' centos@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@ngtech.co.il

-----Original Message----- From: CentOS [mailto:centos-bounces@centos.org] On Behalf Of Laszlo Danielisz Sent: Thursday, August 9, 2018 9:53 PM To: centos@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@centos.org https://lists.centos.org/mailman/listinfo/centos

_______________________________________________ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos

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