Re: NAT problems 14.3+

I found the reason, or better put, workaround for my issue. When =
disabling tx and rxcsum on the vnet internet of the jail, things starts =
to work again.

on the host, ifconfig vnet0.X -txcsum -rxcsum=20

> On 4 May 2026, at 16:28, Rob Bloemers <[email protected]> wrote:
>=20
> FWIW
>=20
> Avoiding in-kernel IPFW NAT and using the rc.firewall / type open with =
natd in userspace, nat seems to function fine for my jails.
>=20
>> On 3 May 2026, at 12:54, Rob Bloemers <[email protected]> =
wrote:
>>=20
>> I've tried this setup now on three different machines at three =
different providers, and each time my simple NAT breaks and i'm still =
clueless on the why. And it prevents me from moving quite a few machines =
from 14.3 to newer releases. What works fine on 14.3 breaks on 14.4 or =
newer, which even worse results on 15.0. Even the ipfw nat example from =
the freebsd manual does not work. I'm sure i cant be the only one with =
this issue?
>>=20
>> Really hope somebody can replicate this for him/herself to confirm =
this and/or give me a solution for my problem.=20
>>=20
>> Kind Regards
>> Rob=20
>>=20
>>> On 23 Apr 2026, at 12:34, Rob Bloemers <[email protected]> =
wrote:
>>>=20
>>> had to quickly upgrade to 14.4 again to return to the broken state. =
But unfortunately -tso -lro does not change the result.
>>>=20
>>> ice0: =
flags=3D1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> =
metric 0 mtu 9000
>>> =
options=3D4e00028<VLAN_MTU,JUMBO_MTU,RXCSUM_IPV6,TXCSUM_IPV6,HWSTATS,MEXTP=
G>
>>>=20
>>> using
>>> ifconfig_ice0=3D"DHCP mtu 9000 -tso -lro -vlanhwtso -vlanhwtag =
-vlanhwfilter"
>>>=20
>>> Inside the jail, the ISP dns stops responding then too strangely. =
Then when i update it to 1.1.1.1 i can resolve again inside the jail.
>>> Then when i ping some domain, the first reply i get is from the =
resolved ip and then i get responses from its own server ip.
>>>=20
>>> (jail)
>>> root@x-mysql:~ # ping nu.nl
>>> PING nu.nl (2.16.245.135): 56 data bytes
>>> 64 bytes from 2.16.245.135: icmp_seq=3D0 ttl=3D50 time=3D4.603 ms
>>> 64 bytes from 57.128.x.y: icmp_seq=3D1 ttl=3D50 time=3D4.588 ms
>>> 64 bytes from 57.128.x.y: icmp_seq=3D2 ttl=3D50 time=3D4.602 ms
>>> 64 bytes from 57.128.x.y: icmp_seq=3D3 ttl=3D50 time=3D4.602 ms
>>>=20
>>> Maybe this can be a clue? (i dont remember seeing this before today)
>>>=20
>>>=20
>>>> On 23 Apr 2026, at 10:22, Andrey V. Elsukov <[email protected]> =
wrote:
>>>>=20
>>>> On 23.04.2026 11:10, Rob Bloemers wrote:
>>>>> Yes sir, via ifconfig and using sysctl.conf && fresh reboot. =
Unfortunately no changed.
>>>>>>=20
>>>>>> Did you try to disable TSO on the ice0 interface?
>>>>=20
>>>> I'm not sure what you have disabled using sysctl.conf, can you show =
the output of:
>>>>=20
>>>> ifconfig ice0 | grep options
>>>>=20
>>>> --=20
>>>> WBR, Andrey V. Elsukov
>>>>=20
>>>>=20
>>>=20
>>>=20
>>=20
>=20
>=20