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Hi, with recent guest installs (both centos 5 and 7) on centos 7 hosts I seem to have to disable checksum offloading using "ethtool -K eth0 tx off" in order to allow traffic to flow a specific route. Basically the guest is installed with IP 192.168.21.10 and a default gateway of 192.168.21.254. Up until that point I can ssh into the system normally. There exists an OpenVPN System with

...when dealing with th routed traffic and not the > regular one. > > Does anyone have an idea what is going on here? Could this be an issue > with the virtio driver? Things are optimized with virtio-net so that no checksum is ever written until the packet reaches a physical NIC. So with commnuication between 2 guest on the same physical host no checksums will ever be done, & it is expected that tcpdump would show corrupt checksums in that case. Normally this is just fine as almost no applications in the guest OS will operate directly on the ethernet packets, so will never even realize...