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I noticed some strange public IP addresses in the ARP table of my Ubuntu laptop. They also keep reappearing quickly after flushing it. The adresses all resolve to bc.googleusercontent.com and only appear on my Server-VLAN (ID 90) as (obviously) "incomplete".

╰─$ arp -a
32.121.122.34.bc.googleusercontent.com (34.122.121.32) auf <unvollständig> auf enp0s25.90
84.170.224.35.bc.googleusercontent.com (35.224.170.84) auf <unvollständig> auf enp0s25.90
router.srv.zhaus (192.168.90.1) auf 00:e0:4c:67:86:63 [ether] auf enp0s25.90
router.zhaus (192.168.1.1) auf 00:e0:4c:67:86:63 [ether] auf enp0s25
17.111.232.35.bc.googleusercontent.com (35.232.111.17) auf <unvollständig> auf enp0s25.90

My routing table looks normal. I also thought maybe it is because VLAN 90 does not route to the internet and it tries to resolve the address but gets stuck in the LAN. But that's just a rather wild guess. It shouldn't even touch this network according to the routing table.

╰─$ ip route
default via 192.168.1.1 dev enp0s25 proto dhcp metric 100 
192.168.1.0/24 dev enp0s25 proto kernel scope link src 192.168.1.105 
192.168.1.0/24 dev enp0s25 proto kernel scope link src 192.168.1.127 metric 100 
192.168.90.0/24 dev enp0s25.90 proto kernel scope link src 192.168.90.100 
192.168.100.0/24 via 192.168.90.1 dev enp0s25.90 

(Yes, enp0s25 has 2 IP addresses)

I don't know if i should be worried, it's probably just some strange phenomena. But i wanted to get a second opinion to that.

thanks.

jogo
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  • https://networkengineering.stackexchange.com/q/50843/645 – Michael Hampton Dec 21 '20 at 18:16
  • As a side note, this would prevent these specific ARP to be working and thus to be cached: `sysctl -w net.ipv4.conf.enp0s25/90.arp_ignore=2` . Of course have a remote console access in case it disrupts connectivity even if it shouldn't. – A.B Dec 22 '20 at 20:36

1 Answers1

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xxx.xxx.xxx.xxx.bc.googleusercontent.com are people using compute engine, part of the cloud services offered by google, so it's not anything related to google themselves crawling your site.

If you think that they are doing something untoward, you can report abuse of the system here: https://support.google.com/code/contact/cloud_platform_report?hl=en

Source: https://support.google.com/webmasters/thread/3056781?hl=en

Peycho Dimitrov
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