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I have a server that has some VMs, but the VMs can't communicate properly with the server because the server has several interfaces, and it responds on the wrong one.

Q: We know that there is a kernel parameter that can ensure that ARP responses will come only from that interface where the request went. What is that sysctl setting?

Server is Debian machine.

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You need to execute:

sysctl -w net.ipv4.conf.all.arp_filter=1

This can be useful reading: Multiple network interfaces and ARP flux

  • this will be only permament if I edit "/etc/sysctl.conf"? – LanceBaynes Feb 7 '12 at 14:59
  • from kernel.org/doc/Documentation/networking/ip-sysctl.txt : arp_filter - BOOLEAN / 1 - Allows you to have multiple network interfaces on the same subnet, In other words it allows control of which cards (usually 1) will respond to an arp request. / 0 - (default) The kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. – Daniel S. Sterling Jun 5 '17 at 20:17

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