Fails to provide network on IPv6-only hosts #207
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helmutg
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The networkd template explicitly disables IPv6-connectivity. When connecting to a host, the attempt to use IPv6 results in -ENETUNREACH from the guest kernel. If the host is IPv6-only, the host kernel likewise makes attempts to use IPv4 result in -ENETUNREACH. Hence fakemachine has dysfunctional network when invoked on an IPv6-only host. Closes: go-debos#207 Signed-off-by: Helmut Grohne <helmut@subdivi.de>
sjoerdsimons
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Feb 16, 2025
The networkd template explicitly disables IPv6-connectivity. When connecting to a host, the attempt to use IPv6 results in -ENETUNREACH from the guest kernel. If the host is IPv6-only, the host kernel likewise makes attempts to use IPv4 result in -ENETUNREACH. Hence fakemachine has dysfunctional network when invoked on an IPv6-only host. Closes: go-debos#207 Signed-off-by: Helmut Grohne <helmut@subdivi.de>
sjoerdsimons
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Feb 16, 2025
The networkd template explicitly disables IPv6-connectivity. When connecting to a host, the attempt to use IPv6 results in -ENETUNREACH from the guest kernel. If the host is IPv6-only, the host kernel likewise makes attempts to use IPv4 result in -ENETUNREACH. Hence fakemachine has dysfunctional network when invoked on an IPv6-only host. Closes: go-debos#207 Signed-off-by: Helmut Grohne <helmut@subdivi.de>
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Running fakemachine on an IPv6-only host results in "Network is unreachable" when trying to access the network. The network stack usually tries IPv6 first, but
machine.gosetsLinkLocalAddressing=noandIPv6AcceptRA=no, so it does not have any IPv6 address nor route and the Linux kernel inside KVM reports-ENETUNREACH. It then falls back to IPv4 and sends a packet. KVM's slirp-based user network stack then tries to send this packet, but observes that the host machine does not have any IPv4 addresses nor routes and generates an ICMPv4 packet indicating-ENETUNREACH. Having failed both address families,-ENETUNREACHis reported to the end user. This makes e.g.debosfail.Debian-Bug: https://bugs.debian.org/1071033
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