Subject: Re: [PATCH net v2 2/4] selftests/net: add no ARP b/mcast,null poison test

From: Jakub Kicinski <[email-masked]>
Date: Wed, 28 Jan 2026 20:27:39 -0800

On Tue, 27 Jan 2026 00:53:03 +0100 Marc Suñé wrote:
> Add a selftest to test that ARP bcast/mcast/null poisioning checks
> are never bypassed.

> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index 45c4ea381bc3..a765f1800752 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -9,6 +9,7 @@ CFLAGS += -I../
>  TEST_PROGS := \
>  	altnames.sh \
>  	amt.sh \
> +	arp_no_invalid_sha_poision.sh \

alphabetical sort pls

>  	arp_ndisc_evict_nocarrier.sh \
>  	arp_ndisc_untracked_subnets.sh \
>  	bareudp.sh \

> +readonly V4_ADDR0="10.0.10.1"
> +readonly V4_ADDR1="10.0.10.2"
> +readonly BCAST_MAC="ff:ff:ff:ff:ff:ff"
> +readonly MCAST_MAC="01:00:5e:00:00:00"
> +readonly NULL_MAC="00:00:00:00:00:00"
> +readonly VALID_MAC="02:01:02:03:04:05"
> +readonly ARP_REQ=1
> +readonly ARP_REPLY=2
> +nsid=100

unused? (please run shellcheck)

> +ret=0
> +veth0_ifindex=0
> +veth1_mac=

> diff --git a/tools/testing/selftests/net/arp_send.c b/tools/testing/selftests/net/arp_send.c
> new file mode 100644

Could you check if mausezahn from netsniff-ng can send these
packets already? We already depend on mausezahn for other tests.

Similar comments on patch 4, I'm not gonna repeat.