Connection from/to 169.254.169.254 google services

[Sylvain Bergé]

Hi,

Can you please explain why internal google name server 169.254.169.254 send TCP request from 80 logical port to the internal instance IP?

In more general terms, what are the default connections from/to Google services with instances images provided by Google?

Thanks.

[Gary Ling]

Hi Sylvain,

Network load balancing service does health check by issuing HTTP requests that originate from this IP. For more, see the doc here.

Hope it helps.

Gary Ling

[Sylvain Bergé]

Hi Gary,

The problem is I didn't set up any check:

$ gcloud compute http-health-checks list

NAME HOST PORT REQUEST_PATH

In addition, the traffic was about :

SRC=169.254.169.254 SPT:80 ===> DST=internal instance IP DPT : 40021 or 40016

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Sylvain

[David Newgas]

Hi Sylvain,

Are you looking at this from a tcpdump? It looks like you are looking at the *response* to a request from your instance to the metadata server.

David

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[Sylvain Bergé]

Hi David,

You right, it could be the explanation.

However, I am surprised because I use the following iptables rule:

pkts bytes target     prot opt in     out     source               destination

 124K   44M ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED

Because I didn't find any other trace, I think it is now fixed.

Thank you for your support.

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Sylvain