Date: Fri, 12 Dec 2025 22:25:29 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 291420] [epair] Bad UDP packet checksum with epair(4) and txcsum enabled Message-ID: <bug-291420-7501-WeIjAOgIFU@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-291420-7501@https.bugs.freebsd.org/bugzilla/> References: <bug-291420-7501@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=291420 leper <leper4@protonmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |leper4@protonmail.com --- Comment #22 from leper <leper4@protonmail.com> --- I encountered the same problem with a slightly different setup that does not involve bge, and then reproduced it on 15.0-RELEASE in a VM with only vtnet, epair, bridge, tap devices involved. A bridge with two vnet jails attached to it. One jail running unbound. The second jail running bhyve and an Ubuntu VM with the vm jail's networking setup being another bridge of the vnet epair and the tap. The host handles routing for the bridge network for outside connectivity. The VM cannot use the unbound server running in the dns jail for DNS, the UDP packets have just a partial checksum (according to Wireshark, and it just not working). The VM can use external DNS servers just fine. If one disables txcsum on the dns jails epair interface it starts working. At least ICMP between the VM and the DNS jail works fine regardless of the txcsum setting. As does DNS from the jail running bhyve. (Out of curiosity I tried if adding the patches for txcsum support for tap devices ( review D51289, review D51291, review D51688) would make a difference (but still on 14-stable) and that also did not change anything.) If it is useful I could provide this test VM image. Host network ``` bridge0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 options=10<VLAN_HWTAGGING> ether 58:9c:fc:10:95:97 inet 172.16.0.1 netmask 0xfff00000 broadcast 172.31.255.255 id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200 root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0 bridge flags=0<> member: e0a_vmjail flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP> port 7 priority 128 path cost 2000 vlan protocol 802.1q member: e0a_dns flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP> port 4 priority 128 path cost 2000 vlan protocol 802.1q groups: bridge nd6 options=3<PERFORMNUD,ACCEPT_RTADV> e0a_dns: flags=1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 description: vnet0 host interface for Bastille jail dns options=60000b<RXCSUM,TXCSUM,VLAN_MTU,RXCSUM_IPV6,TXCSUM_IPV6> ether 58:9c:fc:7f:2f:6a hwaddr 58:9c:fc:10:c5:5f groups: epair media: Ethernet 10Gbase-T (10Gbase-T <full-duplex>) status: active nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> e0a_vmjail: flags=1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 description: vnet0 host interface for Bastille jail vmjail options=20000b<RXCSUM,TXCSUM,VLAN_MTU,RXCSUM_IPV6> ether 58:9c:fc:6c:b0:ca hwaddr 58:9c:fc:10:67:eb groups: epair media: Ethernet 10Gbase-T (10Gbase-T <full-duplex>) status: active nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> ``` vmjail network: ``` vnet0: flags=1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 description: jail interface for bridge0 options=20000b<RXCSUM,TXCSUM,VLAN_MTU,RXCSUM_IPV6> ether 58:9c:fc:6c:b0:cb hwaddr 58:9c:fc:10:13:af groups: epair media: Ethernet 10Gbase-T (10Gbase-T <full-duplex>) status: active nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> bridge1: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 options=10<VLAN_HWTAGGING> ether 9a:e7:95:53:f9:56 inet 172.16.0.2 netmask 0xffffff00 broadcast 172.16.0.255 id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200 root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0 bridge flags=0<> member: tap0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP> port 11 priority 128 path cost 2000000 vlan protocol 802.1q member: vnet0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP> port 8 priority 128 path cost 2000 vlan protocol 802.1q groups: bridge vm-switch viid-4c918@ nd6 options=9<PERFORMNUD,IFDISABLED> tap0: flags=1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500 description: vmnet/linvm/0/public options=80000<LINKSTATE> ether 0e:79:d9:96:d3:03 groups: tap vm-port media: Ethernet 1000baseT <full-duplex> status: active nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> Opened by PID 10785 ``` -- You are receiving this mail because: You are on the CC list for the bug.help
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