Ragnar Wisloff skrev:
I'm observing a puzzling problem. It seems that the DHCP request sent
out by the thin client is subtly different the first and second time
(two DHCP requests are sent during a single boot). The second DHCP
request contains more information, and the DHCPD server sees this as a
different request. Even if the MAC address is the same, they have
different uids and so a different IP is handed out. These two stanzas
from a leases file shows this behaviour:
lease 192.168.199.153 {
starts 3 2005/05/25 09:56:32;
ends 4 2005/05/26 09:56:32;
tstp 4 2005/05/26 09:56:32;
binding state active;
next binding state free;
hardware ethernet 00:50:8b:50:c1:85;
}
lease 192.168.199.245 {
starts 3 2005/05/25 09:56:43;
ends 4 2005/05/26 09:56:43;
tstp 4 2005/05/26 09:56:43;
binding state active;
next binding state free;
hardware ethernet 00:50:8b:50:c1:85;
uid "\001\000P\213P\301\205";
I sniffed a bit of traffic during bootup (see attached packet contents).
The DHCP requests are indeed different (quite a bit different actually).
However, it seems that the last line with the uid is derived from the
second request which contains an explicit
Option 61: Client identifier
Hardware type: Ethernet
Client MAC address: 90:12:02:51:58:34 (10.0.3.103)
It must be this information that makes the DHCP server think there are
two different clients talking to it.
I did try out the "deny duplicates;" line in dhcpd.conf, but that did
not help (Jim never thought it would ;).
So it might be that the two solutions are to either assign fixed IPs or
change the behaviour of the client request during boot. The linuxrc
script seems to call dhcpcd with almost no options, perhaps some more
options could be added. I know too little about dhcpcd.
Ragnar
No. Time Source Destination Protocol Info
35 12.336726 0.0.0.0 255.255.255.255 DHCP DHCP
Discover - Transaction ID 0x3515834
Frame 35 (590 bytes on wire, 590 bytes captured)
Arrival Time: May 26, 2005 09:05:32.991491000
Time delta from previous packet: 1.176060000 seconds
Time since reference or first frame: 12.336726000 seconds
Frame Number: 35
Packet Length: 590 bytes
Capture Length: 590 bytes
Protocols in frame: eth:ip:udp:bootp
Ethernet II, Src: 90:12:02:51:58:34, Dst: ff:ff:ff:ff:ff:ff
Destination: ff:ff:ff:ff:ff:ff (Broadcast)
Source: 90:12:02:51:58:34 (10.0.3.103)
Type: IP (0x0800)
Internet Protocol, Src Addr: 0.0.0.0 (0.0.0.0), Dst Addr: 255.255.255.255
(255.255.255.255)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 576
Identification: 0x0000 (0)
Flags: 0x00
0... = Reserved bit: Not set
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 20
Protocol: UDP (0x11)
Header checksum: 0xa4ae (correct)
Source: 0.0.0.0 (0.0.0.0)
Destination: 255.255.255.255 (255.255.255.255)
User Datagram Protocol, Src Port: bootpc (68), Dst Port: bootps (67)
Source port: bootpc (68)
Destination port: bootps (67)
Length: 556
Checksum: 0xab88 (correct)
Bootstrap Protocol
Message type: Boot Request (1)
Hardware type: Ethernet
Hardware address length: 6
Hops: 0
Transaction ID: 0x03515834
Seconds elapsed: 4
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: 0.0.0.0 (0.0.0.0)
Client MAC address: 90:12:02:51:58:34 (10.0.3.103)
Server host name not given
Boot file name not given
Magic cookie: (OK)
Option 53: DHCP Message Type = DHCP Discover
Option 55: Parameter Request List
1 = Subnet Mask
2 = Time Offset
3 = Router
5 = Name Server
6 = Domain Name Server
11 = Resource Location Server
12 = Host Name
13 = Boot File Size
15 = Domain Name
16 = Swap Server
17 = Root Path
18 = Extensions Path
43 = Vendor-Specific Information
54 = Server Identifier
60 = Vendor class identifier
67 = Bootfile name
128 = Private
129 = Private
130 = Private
131 = Private
132 = Private
133 = Private
134 = Private
135 = Private
Option 57: Maximum DHCP Message Size = 1260
Option 93: Client System Architecture (2 bytes)
Option 94: Client Network Device Interface (3 bytes)
Option 60: Vendor class identifier = "PXEClient:Arch:00000:UNDI:002001"
End Option
Padding
No. Time Source Destination Protocol Info
2821 20.583186 0.0.0.0 255.255.255.255 DHCP DHCP
Discover - Transaction ID 0x45809633
Frame 2821 (590 bytes on wire, 590 bytes captured)
Arrival Time: May 26, 2005 09:05:41.237951000
Time delta from previous packet: 0.265270000 seconds
Time since reference or first frame: 20.583186000 seconds
Frame Number: 2821
Packet Length: 590 bytes
Capture Length: 590 bytes
Protocols in frame: eth:ip:udp:bootp
Ethernet II, Src: 90:12:02:51:58:34, Dst: ff:ff:ff:ff:ff:ff
Destination: ff:ff:ff:ff:ff:ff (Broadcast)
Source: 90:12:02:51:58:34 (10.0.3.103)
Type: IP (0x0800)
Internet Protocol, Src Addr: 0.0.0.0 (0.0.0.0), Dst Addr: 255.255.255.255
(255.255.255.255)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 576
Identification: 0xe2b6 (58038)
Flags: 0x00
0... = Reserved bit: Not set
.0.. = Don't fragment: Not set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 64
Protocol: UDP (0x11)
Header checksum: 0x95f7 (correct)
Source: 0.0.0.0 (0.0.0.0)
Destination: 255.255.255.255 (255.255.255.255)
User Datagram Protocol, Src Port: bootpc (68), Dst Port: bootps (67)
Source port: bootpc (68)
Destination port: bootps (67)
Length: 556
Checksum: 0x25d3 (correct)
Bootstrap Protocol
Message type: Boot Request (1)
Hardware type: Ethernet
Hardware address length: 6
Hops: 0
Transaction ID: 0x45809633
Seconds elapsed: 10
Bootp flags: 0x0000 (Unicast)
0... .... .... .... = Broadcast flag: Unicast
.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: 0.0.0.0 (0.0.0.0)
Client MAC address: 90:12:02:51:58:34 (10.0.3.103)
Server host name not given
Boot file name not given
Magic cookie: (OK)
Option 53: DHCP Message Type = DHCP Discover
Option 57: Maximum DHCP Message Size = 548
Option 51: IP Address Lease Time = infinity
Option 55: Parameter Request List
1 = Subnet Mask
3 = Router
6 = Domain Name Server
12 = Host Name
15 = Domain Name
17 = Root Path
23 = Default IP Time-to-Live
28 = Broadcast Address
29 = Perform Mask Discovery
31 = Perform Router Discover
33 = Static Route
40 = Network Information Service Domain
41 = Network Information Service Servers
42 = Network Time Protocol Servers
Option 60: Vendor class identifier = "Linux 2.4.26-ltsp-3 i686"
Option 61: Client identifier
Hardware type: Ethernet
Client MAC address: 90:12:02:51:58:34 (10.0.3.103)
End Option
Padding
