broken

root@OpenWrt:~# reset; \
> NET_IF="wan"; \
> NET_DEV="$(uci get network.${NET_IF}.ifname)"; \
> ifup "${NET_IF}"; sleep 10; \
> tcpdump -v -n -i "${NET_DEV}" udp port 67 or udp port 68 & \
> ip address show dev "${NET_DEV}"; \
> kill -SIGUSR2 "$(pidof udhcpc)"; sleep 10; \
> ip address show dev "${NET_DEV}"; \
> kill -SIGUSR1 "$(pidof udhcpc)"; sleep 10; \
> ip address show dev "${NET_DEV}"; \
> killall tcpdump
10: eth1.2@eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    link/ether 24:f5:a2:c4:7a:d0 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::26f5:a2ff:fec4:7ad0/64 scope link
       valid_lft forever preferred_lft forever
tcpdump: listening on eth1.2, link-type EN10MB (Ethernet), capture size 262144 bytes
10: eth1.2@eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    link/ether 24:f5:a2:c4:7a:d0 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::26f5:a2ff:fec4:7ad0/64 scope link
       valid_lft forever preferred_lft forever
05:51:26.279006 IP (tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 24:f5:a2:c4:7a:d0, length 300, xid 0xaada861a, Flags [none]
          Client-Ethernet-Address 24:f5:a2:c4:7a:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            MSZ Option 57, length 2: 576
            Parameter-Request Option 55, length 8:
              Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
              Domain-Name, BR, NTP, Classless-Static-Route
            Vendor-Class Option 60, length 12: "udhcp 1.28.4"
            Hostname Option 12, length 7: "OpenWrt"
05:51:29.139002 IP (tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 24:f5:a2:c4:7a:d0, length 300, xid 0xaada861a, secs 3, Flags [none]
          Client-Ethernet-Address 24:f5:a2:c4:7a:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            MSZ Option 57, length 2: 576
            Parameter-Request Option 55, length 8:
              Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
              Domain-Name, BR, NTP, Classless-Static-Route
            Vendor-Class Option 60, length 12: "udhcp 1.28.4"
            Hostname Option 12, length 7: "OpenWrt"
05:51:32.419000 IP (tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 24:f5:a2:c4:7a:d0, length 300, xid 0xaada861a, secs 6, Flags [none]
          Client-Ethernet-Address 24:f5:a2:c4:7a:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            MSZ Option 57, length 2: 576
            Parameter-Request Option 55, length 8:
              Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
              Domain-Name, BR, NTP, Classless-Static-Route
            Vendor-Class Option 60, length 12: "udhcp 1.28.4"
            Hostname Option 12, length 7: "OpenWrt"
05:51:35.189002 IP (tos 0x0, ttl 64, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 24:f5:a2:c4:7a:d0, length 300, xid 0xaada861a, secs 9, Flags [none]
          Client-Ethernet-Address 24:f5:a2:c4:7a:d0
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            MSZ Option 57, length 2: 576
            Parameter-Request Option 55, length 8:
              Subnet-Mask, Default-Gateway, Domain-Name-Server, Hostname
              Domain-Name, BR, NTP, Classless-Static-Route
            Vendor-Class Option 60, length 12: "udhcp 1.28.4"
            Hostname Option 12, length 7: "OpenWrt"
10: eth1.2@eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
    link/ether 24:f5:a2:c4:7a:d0 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::26f5:a2ff:fec4:7ad0/64 scope link
       valid_lft forever preferred_lft forever

4 packets captured
4 packets received by filter
0 packets dropped by kernel
root@OpenWrt:~#