Begin forwarded message: Date: Wed, 06 Jun 2018 18:39:54 +0000 From: bugzilla-dae...@bugzilla.kernel.org To: step...@networkplumber.org Subject: [Bug 199951] New: Packets send with libpcap via veth started to have trailer, (incorrect) FCS and are dropped https://bugzilla.kernel.org/show_bug.cgi?id=199951 Bug ID: 199951 Summary: Packets send with libpcap via veth started to have trailer, (incorrect) FCS and are dropped Product: Networking Version: 2.5 Kernel Version: 4.16.12 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: Other Assignee: step...@networkplumber.org Reporter: piotr.jerzy.jurkiew...@gmail.com Regression: No I have the following configuration: netns0 netns1 veth0 <---------> veth1 Inside netns0 I inject packets with libpcap into veth0. On kernels 4.16.5 and older packets were correctly received on veth1 in netns1. On kernel 4.16.12 most packets are dropped by interface veth1 (but not all, ICMP and TCP connection establishment sequence goes through, large ones are dropped). When observing packets send on veth0 with Wireshark I notice that: - on 4.16.5 packets are 1512 bytes long and do not include Ethernet trailer and FCS - on 4.16.12 packets are 1526 bytes long and include Ethernet trailer and FCS, which is incorrect (either zeros or some garbage) I suspect that the incorrect FCS is the reason why packets are dropped by veth1. Other explanation could be that packets with trailer and FCS are dropped because they are simply too long (this would explain why small packets are received). I do not have access to binaries of kernel versions other than 4.16.5 and 4.16.12 (using Debian sid), so I cannot tell in which exact version between them this regressions has been introduced. -- You are receiving this mail because: You are the assignee for the bug.
