Binding error/bug ?

Lars Jacobsen lj at sydfynsel.dk
Fri Apr 20 09:22:14 UTC 2007


Hi list.

According to previous information on the list, IP leases are bound to
either Client ID and/or MAC. But witch MAC ?

I have noticed that if the discover packet (like the one at the bottom)
witch is coming though a relay agent, the IP is being bound to the relay
agent's MAC, and not the MAC listed in the option 61. The information
from option 12 (Hostname) is also recorded in the lease file. 

But shouldn't the lease file (DHCPd) bind the IP to the "real Client
MAC" contained in option 61, not the "Client MAC" that's sending the
packet to the DHCP server ?

Regards
Lars




Packetyzer Trace:

Frame 1 (544 bytes on wire, 544 bytes captured)
     Frame is marked: False
     Arrival Time: Apr 13, 2007 09:36:13.508328000
     Time delta from previous packet: -5.641955000 seconds
     Time since reference or first frame: 45.356884000 seconds
     Frame Number: 1
     Packet Length: 544 bytes
     Capture Length: 544 bytes
     Protocols in frame: eth:ip:udp:bootp
Ethernet II, Src: 00:04:96:10:a6:e0, Dst: 00:11:85:5c:8d:43
     Destination: 00:11:85:5c:8d:43 (HewlettP_5c:8d:43)
     Source: 00:04:96:10:a6:e0 (ExtremeN_10:a6:e0)
     Source or Destination Address: 00:11:85:5c:8d:43
(HewlettP_5c:8d:43)
     Source or Destination Address: 00:04:96:10:a6:e0
(ExtremeN_10:a6:e0)
     Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.101.1 (192.168.101.1), Dst Addr:
192.168.101.20 (192.168.101.20)
     Version: 4
     Header length: 20 bytes
     Differentiated Services Field: 0x40 (DSCP 0x10: Class Selector 2;
ECN: 0x00)
          0100 00.. = Differentiated Services Codepoint: Class Selector
2 (0x10)
          .... ..0. = ECN-Capable Transport (ECT): 0
          .... ...0 = ECN-CE: 0
     Total Length: 530
     Identification: 0x1236 (4662)
     Flags: 0x00
          0... = Reserved bit: Not set
          .0.. = Don't fragment: Not set
          ..0. = More fragments: Not set
     Fragment offset: 0
     Time to live: 59
     Protocol: UDP (0x11)
     Header checksum: 0x1fff (correct)
     Source: 192.168.101.1 (192.168.101.1)
     Source or Destination Address: 192.168.101.1 (192.168.101.1)
     Destination: 192.168.101.20 (192.168.101.20)
     Source or Destination Address: 192.168.101.20 (192.168.101.20)
User Datagram Protocol, Src Port: bootpc (68), Dst Port: bootps (67)
     Source port: bootpc (68)
     Destination port: bootps (67)
     Source or Destination Port: 68
     Source or Destination Port: 67
     Length: 510
     Checksum: 0x46c0 (correct)
Bootstrap Protocol
     Message type: Boot Request (1)
     Hardware type: Ethernet
     Hardware address length: 6
     Hops: 1
     Transaction ID: 0xb9800e56
     Seconds elapsed: 0
     Bootp flags: 0x8000 (Broadcast)
          1... .... .... .... = Broadcast flag: Broadcast
          .000 0000 0000 0000 = Reserved flags: 0x0000
     Client IP address: 0.0.0.0 (0.0.0.0)
     Your (client) IP address: 0.0.0.0 (0.0.0.0)
     Next server IP address: 0.0.0.0 (0.0.0.0)
     Relay agent IP address: 85.27.148.193 (85.27.148.193)
     Client MAC address: 00:06:0d:4d:c0:be (HP_4d:c0:be)
     Server host name not given
     Boot file name not given
     Magic cookie: (OK)
     Frame is DHCP: True
     Option 53: DHCP Message Type = DHCP Discover
     Option 61: Client identifier
          Hardware type: Ethernet
          Client MAC address: 00:50:b9:80:0e:56 (XitronTe_80:0e:56)
     Option 12: Host Name = "0050B9800E56"
     Option 55: Parameter Request List
          1 = Subnet Mask
          3 = Router
          6 = Domain Name Server
          54 = Server Identifier
     Option 82: Agent Information Option (9 bytes)
          Suboption 1: no room left in option for suboption value
     End Option
     Padding

0000:  00 11 85 5C 8D 43 00 04 96 10 A6 E0 08 00 45 40  ...\.C........E@
0010:  02 12 12 36 00 00 3B 11 1F FF C0 A8 65 01 C0 A8  ...6..;.....e...
0020:  65 14 00 44 00 43 01 FE 46 C0 01 01 06 01 B9 80  e..D.C..F.......
0030:  0E 56 00 00 80 00 00 00 00 00 00 00 00 00 00 00  .V..............
0040:  00 00 55 1B 94 C1 00 06 0D 4D C0 BE 00 00 00 00  ..U......M......
0050:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0060:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0070:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0080:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0090:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00A0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00B0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00C0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00D0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00E0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
00F0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0100:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0110:  00 00 00 00 00 00 63 82 53 63 35 01 01 3D 07 01  ......c.Sc5..=..
0120:  00 50 B9 80 0E 56 0C 0C 30 30 35 30 42 39 38 30  .P...V..0050B980
0130:  30 45 35 36 37 04 01 03 06 36 52 09 01 07 31 30  0E567....6R...10
0140:  30 31 30 31 31 FF 00 00 00 00 00 00 00 00 00 00  01011...........
0150:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0160:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0170:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0180:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0190:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
01A0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
01B0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
01C0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
01D0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
01E0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
01F0:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0200:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0210:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................



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