Commit 1e21a82c authored by Petr Pudlak's avatar Petr Pudlak

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 https://bugs.launchpad.net/bugs/930962

By turning them off completely using ethtool, we work around the
problem.
Signed-off-by: default avatarPetr Pudlak <pudlak@google.com>
Reviewed-by: default avatarKlaus Aehlig <aehlig@google.com>
parent 2175eb1c
......@@ -184,6 +184,18 @@ fi
# parameters does not produce an error.
ifconfig $INTERFACE 169.254.169.254 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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