B #7691: loosen inherited ARP strictness in netns#7692
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to allow cross-subnet ARP replies. Network namespaces can inherit strict ARP policies (where arp_ignore is greater than 0) from the host's default configurations. When this strictness is inherited, it breaks cross-subnet ARP resolution. Specifically, the namespace silently drops and fails to reply to the VM's cross-subnet ARP requests for local endpoints, such as the 169.254.16.9. This PR explicitly loosens the inherited ARP strictness by forcing arp_ignore=0 inside the namespace. By applying this to both all and the specific interface, it guarantees the namespace will successfully reply to the VM's ARP requests for local IPs.
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Description
to allow cross-subnet ARP replies.
Network namespaces can inherit strict ARP policies (where arp_ignore is greater than 0) from the host's default configurations. When this strictness is inherited, it breaks cross-subnet ARP resolution. Specifically, the namespace silently drops and fails to reply to the VM's cross-subnet ARP requests for local endpoints, such as the 169.254.16.9.
This PR explicitly loosens the inherited ARP strictness by forcing arp_ignore=0 inside the namespace. By applying this to both all and the specific interface, it guarantees the namespace will successfully reply to the VM's ARP requests for local IPs.
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