# DF-2253 end-to-end, FIXED kernel (kernel #2 Sat Oct 17 16:28:39 UTC 2026, fix.diff applied)
guest# /root/arp_inject; sleep 2; dmesg | grep -i "arp:" | tail -2
arp_inject: wrote 42 bytes to /dev/tap0 (ar_hrd=0x1234)
arp: unknown hardware address format (0x1234)
# Full four-digit hardware-format value now logged.