Magic Cookie Error

[mcmar]

I'm testing this package. When my Android phone attempts to connect and asks for an IPv4 address, I get this error:

2022/05/18 22:02:15  warn failed to serve request from <32:b1:27:a1:dc:81>0.0.0.0:68: malformed DHCP packet: got magic cookie [0 0 0 0], want [99 130 83 99]

This is my Dhcpfile:

192.168.1.64 - 192.168.1.253
lease 1h
option {
    router 192.168.1.254
    nameserver 8.8.8.8
}

Have I done something wrong? I don't know why Android would make a DHCP request with a malformed packet and it seems to work with other DHCP servers I've tried, such as a standard off-the-shelf consumer router.

[ppacher]

Hi @mcmar, thanks for reporting.

I'm not sure whats up here. The value of the magic cookie has been fixed to 99 130 83 99 in RFC1048. I'm not sure why your phone does not send it as expected. Could you try to catch the DHCP request message using tcpdump (see here)? Maybe that can help us to get some more insights into the problem.

Also, what android version are you using?

[czerwe]

Hi, i have the same issue here with an iPhone

• serving request from <12:49:dc:33:90:a4>0.0.0.0:68
• failed to serve request from <12:49:dc:33:90:a4>0.0.0.0:68: malformed DHCP packet: got magic cookie [0 0 0 0], want [99 130 83 99]

i did a tcpdump

 20:33:22.174028 12:49:dc:33:90:a4 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 342: (tos 0x0, ttl 255, id 10023, offset 0, flags  [none], proto UDP (17), length 328)
0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from 12:49:dc:33:90:a4, length 300, xid 0x9a048d0e, Flags [none] (0x0000)
      Client-Ethernet-Address 12:49:dc:33:90:a4
      Vendor-rfc1048 Extensions
        Magic Cookie 0x63825363
        DHCP-Message Option 53, length 1: Request
        Parameter-Request Option 55, length 9:
          Subnet-Mask, Classless-Static-Route, Default-Gateway, Domain-Name-Server
          Domain-Name, Option 108, URL, Option 119
          Option 252
        MSZ Option 57, length 2: 1500
        Client-ID Option 61, length 7: ether 12:49:dc:33:90:a4
        Requested-IP Option 50, length 4: 10.0.10.186
        Lease-Time Option 51, length 4: 7776000

I looks like there are correct Magic cookie information's.