Commit 1e21a82c authored by Petr Pudlak's avatar Petr Pudlak
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Turn off UDP packet checksums on the metadata interface

There appears to be a bug that UDP packet checksums aren't computed on
the way from a host to a guest, which means the recipient just drops
them. See

By turning them off completely using ethtool, we work around the
Signed-off-by: default avatarPetr Pudlak <>
Reviewed-by: default avatarKlaus Aehlig <>
parent 2175eb1c
......@@ -184,6 +184,18 @@ fi
# parameters does not produce an error.
ifconfig $INTERFACE netmask $NETMASK up
# There is a known bug where UDP packets comming from a host to a XEN
# guest are missing checksums. There are several ways how to tackle the
# issue, for example fixing the checksums using iptables (requires a
# newer version):
# iptables -A POSTROUTING -t mangle -p udp --dport bootpc -j CHECKSUM \
# --checksum-fill
# The easiest one currently seems to be to just turn checksumming off
# for this direction:
ethtool -K $INTERFACE tx off || true
# Configure the routing table
# Given that all TAP network interfaces in the instance communication
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