Hi guys, i need help with an issue on dhcp,
I have encountered this problem on an ar750s and a x750V2C6
on both i use the same gl-inet version and openwrt and kernel
this is my version of gl-inet 3.203
the kernel version is 4.14.221
and this is my version of openwrt
DISTRIB_ID=‘OpenWrt’
DISTRIB_RELEASE=‘19.07.7’
DISTRIB_REVISION=‘r11306-c4a6851c72’
DISTRIB_TARGET=‘ath79/nand’
DISTRIB_ARCH=‘mips_24kc’
DISTRIB_DESCRIPTION=‘OpenWrt 19.07.7 r11306-c4a6851c72’
DISTRIB_TAINTS=‘busybox’
My scenario is:
on the ar750s i configure a bridge
when a device connects to wifi send a dhcp request over the vpn tunnel that reach the server
this is the dhcp request
11:38:57.204924 IP (tos 0x10, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 340)
0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from b2:98:3d:a5:43:a6, length 312, xid 0x72428b8a, Flags [none] (0x0000)
Client-Ethernet-Address b2:98:3d:a5:43:a6
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Request
Client-ID Option 61, length 7: ether b2:98:3d:a5:43:a6
Requested-IP Option 50, length 4: 172.16.178.57
Server-ID Option 54, length 4: 172.16.176.1
MSZ Option 57, length 2: 1500
Vendor-Class Option 60, length 15: “android-dhcp-11”
Hostname Option 12, length 10: “OnePlus-8T”
Parameter-Request Option 55, length 12:
Subnet-Mask, Default-Gateway, Domain-Name-Server, Domain-Name
MTU, BR, Lease-Time, RN
RB, Vendor-Option, URL, Option 108
the dhcp server reply with
11:38:57.217904 IP (tos 0xc0, ttl 64, id 10112, offset 0, flags [none], proto UDP (17), length 328)
172.16.176.1.67 > 172.16.178.57.68: [udp sum ok] BOOTP/DHCP, Reply, length 300, xid 0x72428b8a, Flags [none] (0x0000)
Your-IP 172.16.178.57
Server-IP 172.16.176.1
Client-Ethernet-Address b2:98:3d:a5:43:a6
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: 172.16.176.1
Lease-Time Option 51, length 4: 3600
RN Option 58, length 4: 1800
RB Option 59, length 4: 3150
Subnet-Mask Option 1, length 4: 255.255.252.0
BR Option 28, length 4: 172.16.179.255
Default-Gateway Option 3, length 4: 172.16.176.1
Domain-Name-Server Option 6, length 4: 172.16.176.1
and this is the packet that reach the wifi device
11:38:57.221251 IP (tos 0xc0, ttl 64, id 10112, offset 0, flags [none], proto UDP (17), length 328)
172.16.176.1.67 > 172.16.178.57.68: [udp sum ok] BOOTP/DHCP, Reply, length 300, xid 0x72428b8a, Flags [none] (0x0000)
Your-IP 172.16.178.57
Server-IP 172.16.176.1
Client-Ethernet-Address b2:98:3d:a5:43:a6
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: 172.16.176.1
Lease-Time Option 51, length 4: 3600
RN Option 58, length 4: 1800
RB Option 59, length 4: 3150
Subnet-Mask Option 1, length 4: 255.255.252.0
BR Option 28, length 4: 172.16.179.255
Domain-Name-Server Option 6, length 4: 172.16.176.1
as you can see DHCP option 3 is dropped and the device can’t reach internet because the default route is not created,
but the strange thing is that the scenario described above works with glinet versione
3.015
and with openwrt version
DISTRIB_ID=‘OpenWrt’
DISTRIB_RELEASE=‘18.06.1’
DISTRIB_REVISION=‘r7258-5eb055306f’
DISTRIB_TARGET=‘ar71xx/nand’
DISTRIB_ARCH=‘mips_24kc’
DISTRIB_DESCRIPTION=‘OpenWrt 18.06.1 r7258-5eb055306f’
DISTRIB_TAINTS=‘’