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Mon, 16 Feb 2026 20:27:03 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 293227] VNET jail regression on 14-STABLE from 14.3 using bridge and epair Date: Mon, 16 Feb 2026 20:27:02 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 14.3-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: tom@eborcom.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated List-Id: Bug reports List-Archive: https://lists.freebsd.org/archives/freebsd-bugs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-bugs@FreeBSD.org MIME-Version: 1.0 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D293227 Bug ID: 293227 Summary: VNET jail regression on 14-STABLE from 14.3 using bridge and epair Product: Base System Version: 14.3-STABLE Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: tom@eborcom.com I am running a recent 14-STABLE (14-n273651-d7207388cc58) and I see a netwo= rk regression from 14.3-RELEASE running VNET jails using bridge(4) and epair(4= ). The problem occurs when a client receives data from an IPv6 TCP server runn= ing in a VNET jail when the jail has a larger MTU than either the client or ano= ther device that packets route through. I noticed this using a wg(4) tunnel with mtu 1420 between the client and server. On 14.3-RELEASE, the jail receives an "ICMP6, packet too big" message which causes it to send smaller packets, but on 14-STABLE the jail repeatedly receives these ICMP messages but does not decrease the size of packets it sends. I first noticed this problem running an nginx server in the jail and curl(1= ) on the client, but can also reproduce it running nc(1). To reproduce the problem, create a VNET jail using bridge(4) in epair(4), w= ith the bridge and jailed epair interface having IPv6 addresses within the same prefix. The jail host needs the "net.inet6.ip6.forwarding" sysctl set. The client needs to have a smaller mtu that the jail's bridge and epair interfa= ces, which default to 1500. I notice that 503bf058cd0 was committed to STABLE-14 after 14.3 release to checksum offloading support for epair, but I don't know if this matters. Please let me know if you would like me to run any specific diagnostic commands, test experimental code, or if you need more detail about what I observe. --=20 You are receiving this mail because: You are the assignee for the bug.=