dhcpcd-discuss

Hi Steffano

Sorry for the late reply, I struggled to get a new Linux VM working.

On 09/01/2019 10:50, Stefano Cappa wrote:
> Hi everyone, this is my first mail in this mailing list.
>
> I'm using dhcpcd 6.11.5 on an embedded device with yocto thud (Linux 4.9 
> based).
> I'm using the official porting of dhcpcd in open-embedded, but probably 
> this is not relevant.
>
> I'm trying to run Apple bonjour conformance test 1.5.0 released at the 
> beginning of December. Everything is perfect with ipv6, but when I try 
> with IPv4 I get en error about arp announcements.
>
> Conformance test runs this test (as defined by Apple): "The operator 
> disconnects and reconnects the device's network cable. The test tool 
> verifies that the device repeats its address probing to verify that its 
> address is still unique. The test tool denies the first probe and 
> verifies that the device picks a new address and probes/announces again. 
> It is a warning if the device does not use its original address as its 
> first probing candidate."
>
> But it throws this message:" arp src dst address mismatch: Did not 
> receive 2 announcements after 3 unanswered probes" because it is an arp 
> packet with target address equals to the DNS IPv4 address (because I'm 
> running also mdns).
>
> As I know this apr behaviour is defined in rfc 5227, but it seems that 
> dhcpcd is not following the specification about 3 probes and 2 arp 
> announcements.
>
> I'm not an expert about networking in Linux, so I could saying stupid 
> things.
>
> Is this an issue of dhcpcd 6.11.5?

Not that I know of.
I just spun up a new Arch Linux VM, and tried both dhcpcd-6.11.5 and the 
latest 7.0.8 release.
I simulated the removal and insertion of the cable by doing:
	ip link set down dev ens4
	ip link set up dev ens4

dhcpcd then did 3 ARP probes followed by 2 ARP announcements which I 
verified with wireshark.
You should be able to see this as well if you add the word debug to 
/etc/dhcpcd.conf

> How can I fix it to pass 
> certification?

I have no idea as from my perspective it works fine.

> Dhcpcd 7 fixes this problem (I cannot try it quickly 
> because the porting is still not available and it isn't so simple).
Well, if dhcpcd-7 works for you then use dhcpcd-7?
Porting is actually very easy, why do you think it's not so simple?

Roy