The main question would be _why_ do you use LB in the first place. The
reasonable solution depends on the answer to this question.
If you had a network-level load-balancer, it would work without any
further configuration, as you have a proxy-type load-balancer, it's only
natural to have the LB IP as your $fromhost-ip and there is not much you
can do about.it.
You either need to configure your sources to provide individually
distinguishable source identifiers in the events (so that if you have
multiple logging servers they don't all report hostname of "server1") or
think about reorganizing your infrastructure.
In syslog there is no concept of "headers" so you can't add proxy
headers on your nginx. If you want to modify your event on the
loadbalancer, you'd need to use a syslog daemon (rsyslog?) for
load-balancing. But that seems a bit overengineered since probably just
a single rsyslog receiving events would suffice.
MK
On 22.08.2023 10:58, JPIM (Jan Primdahl Madsen) via rsyslog wrote:
Hello All rsyslog users and developers 😊
The main problem.
When receiving loadbalanced TCP syslog messages our Loadbalancer IP is the IP
added to the variable $fromhost-ip no matter what we do. This is due to the
fact that the LB is doing TCP routing and becomes the sending IP on the network
layer. The syslog message does not contain the IP of the sending node.
The Setup:
The setup contains only 2 servers which have 2 subnets (Frontend and a
Backend(For TCP messages))
The servers are using the following software
* Nginx (For LB)
* Keepalived (For VIP handling)
* Rsyslog (yes for syslog messages)
Question 1:
I was thinking about adding some Proxy Headers to the log message on the LB
(nginx) side and then using that in rsyslog to overwrite the $fronhost-ip. Is
this possible in anyway to have rsyslog to use Proxy Headers like:
* X-Forwarded-For
* X-Real-IP
If possible howto do it ?
If not, any other great suggestions to preserve IP address of sending source in
a LB TCP syslog setup is appreciated
Please be aware, adding more HW to the setup is not an option.
Best regards
Jan P. Madsen
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