[Bug 292319] [network: fibs] traffic comes from the wrong fib in some cases.

From: <bugzilla-noreply_at_freebsd.org>
Date: Wed, 11 Mar 2026 06:26:36 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292319

--- Comment #4 from William Brown <william@firstyear.id.au> ---

Please answer the questions below to help me reproduce:
1. sysctl output of your:
1.1. net.inet.ip.forwarding

net.inet.ip.forwarding: 1

1.2. net.inet.icmp.drop_redirect

net.inet.icmp.drop_redirect: 0  (during the issue)

2. what is your openvpn configuration?
2.1. is it client or server?

client

2.2. any `dev` interface specified?

# openvpn_instance.conf
dev-type tun
dev tun5

# /etc/rc.conf
cloned_interfaces="... tun5"
ifconfig_tun5="fib 1"


2.3. what is your `topology` configuration? subnet? p2p?

subnet

2.4. on ifconfig -v tun5, what is your driver name? openvpn? tun?

tun5: flags=1008051<UP,POINTOPOINT,RUNNING,MULTICAST,LOWER_UP> metric 0 mtu
1500
        options=4080000<LINKSTATE,MEXTPG>
        inet 10.149.210.138 --> 10.149.210.137 netmask 0xffffffff
        inet6 fe80::5a9c:fcff:fe0a:5755%tun5 prefixlen 64 scopeid 0xb
        inet6 2a07:de40:b2bf:1b::10a1 prefixlen 64
        groups: tun
        fib: 1
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        Opened by PID 81039
        drivername: tun5

3. netstat -rn4 output of both fibs after before and after receiving redirect:
3.1. netstat -rn4F1
3.2. netstat -rn4F5

BEFORE:

roxie% sudo -s
roxie# netstat -rn4F1
Routing tables (fib: 1)

Internet:
Destination        Gateway            Flags         Netif Expire
default            172.24.17.1        UGS          vtnet1
10.0.0.0/8         link#11            US             tun5
10.149.242.41      link#11            UH             tun5
10.149.242.42      link#7             UHS             lo0
127.0.0.1          link#7             UHS             lo0
137.65.0.0/16      link#11            US             tun5
147.2.0.0/16       link#11            US             tun5
149.44.0.0/16      link#11            US             tun5
151.155.128.0/17   link#11            US             tun5
164.99.0.0/16      link#11            US             tun5
172.24.17.0/24     link#2             U            vtnet1
172.24.17.24       link#7             UHS             lo0
roxie# netstat -rn4F5
Routing tables (fib: 5)

Internet:
Destination        Gateway            Flags         Netif Expire
default            172.24.17.1        UGS          vtnet5
127.0.0.1          link#7             UHS             lo0
172.24.17.0/24     link#6             U            vtnet5
172.24.17.26       link#7             UHS             lo0

AFTER:

roxie# netstat -rn4F1
Routing tables (fib: 1)

Internet:
Destination        Gateway            Flags         Netif Expire
default            172.24.17.1        UGS          vtnet1
10.0.0.0/8         link#11            US             tun5
10.149.242.41      link#11            UH             tun5
10.149.242.42      link#7             UHS             lo0
127.0.0.1          link#7             UHS             lo0
137.65.0.0/16      link#11            US             tun5
147.2.0.0/16       link#11            US             tun5
149.44.0.0/16      link#11            US             tun5
151.155.128.0/17   link#11            US             tun5
164.99.0.0/16      link#11            US             tun5
172.24.17.0/24     link#2             U            vtnet1
172.24.17.24       link#7             UHS             lo0
roxie# netstat -rn4F5
Routing tables (fib: 5)

Internet:
Destination        Gateway            Flags         Netif Expire
default            172.24.17.1        UGS          vtnet5
127.0.0.1          link#7             UHS             lo0
172.24.17.0/24     link#6             U            vtnet5
172.24.17.26       link#7             UHS             lo0

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