Re: Does the debian kernel sends the gratuitous arp ?
On Mon, Oct 09, 2023 at 08:39:02PM +0530, Balaji G wrote:
> Hi Geert,
Hello mailinglist (archive )readers of debian-user@lists.debian.org
> >>> During `ip link set down dev eno5np0` and `ip link set up dev eno5np0`
> >>> are NO IP-addresses involved.
>
> This interface eno5np0 is configured with the ip addresses(10.45.10.4 ).
>
> # ifconfig
} ( mismatch between `ifconfig` command expected `ifconfig` output )
> eno5np0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
> inet 10.45.10.4 netmask 255.255.255.0 broadcast 10.45.10.255
> ether 88:e9:a4:49:18:48 txqueuelen 1000 (Ethernet)
> RX packets 2967346895 bytes 4417546189260 (4.0 TiB)
> RX errors 0 dropped 1 overruns 0 frame 0
> TX packets 1634521866 bytes 2220475762246 (2.0 TiB)
> TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
I did missed "LOWER_UP", then I noticed that `ifconfig` is used. More
on that later. Back to 'Subject: Re: Does the debian kernel sends the
gratuitous arp ?'
To me is the answer "Yes, Debian kernel sends gratuitous ARP when it
supposed to do". But we, this mailinglist, have this discussion because
somewhere is the gratuitous ARP missing. What triggered the "I wonder
why there is no gratuitous ARP?" is yet unknown.
Let me try to capture a gratuitous ARP. I will be using only one
interface (it is OK if the computer has many other network interfaces)
Using two logins as root, one for "tcpdump", the other "set address".
In "tcpdump session"
tcpdump -n -i eth0 arp
In "set address session"
sudo ip address add 198.51.100.23/24 dev eth0
Back to "tcpdump session".
And to my surprise: **no** gratuitous ARP !
It should be there. I even tried after:
$ cat /proc/sys/net/ipv4/conf/eth0/arp_notify
0
$ echo 1 | sudo tee -a /proc/sys/net/ipv4/conf/eth0/arp_notify
1
$ cat /proc/sys/net/ipv4/conf/eth0/arp_notify
1
$
I'm gonna sleep about. Expect me back over 48 hours.
> Thanks,
Yeah, thanks for the good question.
> Balaji
Groeten
Geert Stappers
About ifconfig :
https://serverfault.com/questions/633087/where-is-the-statement-of-deprecation-of-ifconfig-on-linux
--
Silence is hard to parse
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