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Date:      Fri, 20 Jun 2025 15:43:51 +0200 (CEST)
From:      Ronald Klop <ronald-lists@klop.ws>
To:        Karl Denninger <karl@denninger.net>
Cc:        freebsd-net@freebsd.org
Subject:   Re: dhcpcd(8) into FreeBSD base
Message-ID:  <549425506.8980.1750427031217@localhost>
In-Reply-To: <5f4fe904-dda8-42d8-8325-dd3bb0403df8@denninger.net>
References:  <e401671f-6a67-49ed-bc41-e8fbb9de27cb@www.fastmail.com> <CAPyFy2BackF0FshyjfV6qoOoJjFqiqcu%2BVxx9X_%2BRHpepOXTsw@mail.gmail.com> <18ff2d4772a.129dde187836962.5411001908566459400@marples.name> <bf3f1d62-70bb-4191-82ae-d8c9358d0b47@denninger.net> <1188806329.62817.1750321263908@localhost> <5f4fe904-dda8-42d8-8325-dd3bb0403df8@denninger.net>

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I have tried the "noip4ll" and "noarp" option. Didn't change anything.

My issue ended up that dhcpcd said in the logs it would sent a dhcp packet (the port 67/68 thing), but nothing appeared on the network. And so the lease timed out after a long time and it removed the IP address from the interface.

Ronald.

 
Van: Karl Denninger <karl@denninger.net>
Datum:vrijdag, 20 juni 2025 15:24
Aan:freebsd-net@freebsd.org
Onderwerp:Re: dhcpcd(8) into FreeBSD base
> 
> On 6/19/2025 04:21, Ronald Klop wrote:
>> Hi,
>> 
>> I don't know the details about your setup, but I tried dhcpcd in my network last few months and I encountered that it:
>> 
>> - runs fine in a 14.X jail on a 14.X machine (RPI3B) for both IP4 and IP6
>> - it does not work well on a 14.X jail on a 15.x machines. (RPI4)
>> 
>> The symptoms look a lot like what you describe. Sometimes it got an address and a day later it was gone again. Restarting sometimes helped, often didn't change anything.
>> Up to the point that I started reading to code of dhcpcd and encountered that it writes a line in the log about getting a lease and the next statement was sending a packet out on the network and I never see that packet in tcpdump.
>> 
>> Anyway on the RPI3 I still use it. On the RPI4 I went back to dhclient + SLAAC after I put a lot of time in tcpdumping and testing. Maybe it is just that 14 userland doesn't match enough with 15 kernel to do BPF/dhcp. But than again.... with dhclient it works fine.
>> 
>> I didn't run dhcpcd yet on the host OS yet as I was first testing it in the VNET jails.
>> 
>> Just my 2 cents.
>> 
>> Regards,
>> Ronald.
>>  > 
> Now that's very curious.
> 
> Could you (where you can control what's going on with the other end, which I can't) try again with "noip4ll" and "noarp" and see if you still get the oddness?
> 
> I have a suspicion this is the cause (from the docs "noarp" should be enough to disable both, but never hurts to stick 'em both in there) -- and if so then perhaps default behavior should be changed.
> 
> --
> Karl Denninger
> karl@denninger.net
> The Market Ticker
> [S/MIME encrypted email preferred]
>  

 
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I have tried the&nbsp;"noip4ll" and "noarp" option. Didn't change anything.<br>
<br>
My issue ended up that dhcpcd said in the logs it would sent a dhcp packet (the port 67/68 thing), but nothing appeared on the network. And so the lease timed out after a long time and it removed the IP address from the interface.<br>
<br>
Ronald.<br>
<br>
&nbsp;
<p><strong>Van:</strong> Karl Denninger &lt;karl@denninger.net&gt;<br>
<strong>Datum:</strong>vrijdag, 20 juni 2025 15:24<br>
<strong>Aan:</strong>freebsd-net@freebsd.org<br>
<strong>Onderwerp:</strong>Re: dhcpcd(8) into FreeBSD base</p>

<blockquote style="padding-right: 0px; padding-left: 5px; margin-left: 5px; border-left: #000000 2px solid; margin-right: 0px">
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<div class="moz-cite-prefix">On 6/19/2025 04:21, Ronald Klop wrote:</div>

<blockquote>Hi,<br>
<br>
I don't know the details about your setup, but I tried dhcpcd in my network last few months and I encountered that it:<br>
<br>
- runs fine in a 14.X jail on a 14.X machine (RPI3B) for both IP4 and IP6<br>
- it does not work well on a 14.X jail on a 15.x machines. (RPI4)<br>
<br>
The symptoms look a lot like what you describe. Sometimes it got an address and a day later it was gone again. Restarting sometimes helped, often didn't change anything.<br>
Up to the point that I started reading to code of dhcpcd and encountered that it writes a line in the log about getting a lease and the next statement was sending a packet out on the network and I never see that packet in tcpdump.<br>
<br>
Anyway on the RPI3 I still use it. On the RPI4 I went back to dhclient + SLAAC after I put a lot of time in tcpdumping and testing. Maybe it is just that 14 userland doesn't match enough with 15 kernel to do BPF/dhcp. But than again.... with dhclient it works fine.<br>
<br>
I didn't run dhcpcd yet on the host OS yet as I was first testing it in the VNET jails.<br>
<br>
Just my 2 cents.<br>
<br>
Regards,<br>
Ronald.<br>
&nbsp;</blockquote>

<p>Now that's very curious.</p>

<p>Could you (where you can control what's going on with the other end, which I can't) try again with "noip4ll" and "noarp" and see if you still get the oddness?</p>

<p>I have a suspicion this is the cause (from the docs "noarp" should be enough to disable both, but never hurts to stick 'em both in there) -- and if so then perhaps default behavior should be changed.</p>

<div class="moz-signature">--<br>
Karl Denninger<br>
<a class="moz-txt-link-freetext" href="mailto:karl@denninger.net">karl@denninger.net</a><br>
<i>The Market Ticker</i><br>
<font size="-2"><i>[S/MIME encrypted email preferred]</i></font></div>
</div>
</div>

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