On 08/18/18 17:24, Jonathan Ryshpan wrote:
I had thought that the DHCP communication tells computers attached to
the router
how to set up their routing, /etc/resolv.conf, etc. Maybe not.
Yes, it does.
This is a typical DHCP response.... As you can see, it tells the client the IP
address, subnet mask, broadcast address, DNS server, and Default router.
Frame 8505: 345 bytes on wire (2760 bits), 345 bytes captured (2760 bits) on interface 0
Ethernet II, Src: Synology_76:13:a8 (00:11:32:76:13:a8), Dst: PcsCompu_d7:8c:f0
(08:00:27:d7:8c:f0)
Internet Protocol Version 4, Src: 192.168.1.1, Dst: 192.168.1.80
User Datagram Protocol, Src Port: 67, Dst Port: 68
Bootstrap Protocol (ACK)
Message type: Boot Reply (2)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xb06cb07f
Seconds elapsed: 0
Bootp flags: 0x0000 (Unicast)
0... .... .... .... = Broadcast flag: Unicast
.000 0000 0000 0000 = Reserved flags: 0x0000
Client IP address: 0.0.0.0
Your (client) IP address: 192.168.1.80
Next server IP address: 192.168.1.1
Relay agent IP address: 0.0.0.0
Client MAC address: PcsCompu_d7:8c:f0 (08:00:27:d7:8c:f0)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type (ACK)
Length: 1
DHCP: ACK (5)
Option: (54) DHCP Server Identifier
Length: 4
DHCP Server Identifier: 192.168.1.1
Option: (51) IP Address Lease Time
Length: 4
IP Address Lease Time: (86400s) 1 day
Option: (58) Renewal Time Value
Length: 4
Renewal Time Value: (43200s) 12 hours
Option: (59) Rebinding Time Value
Length: 4
Rebinding Time Value: (75600s) 21 hours
Option: (1) Subnet Mask
Length: 4
Subnet Mask: 255.255.255.0
Option: (28) Broadcast Address
Length: 4
Broadcast Address: 192.168.1.255
Option: (12) Host Name
Length: 7
Host Name: f28k-b1
Option: (252) Private/Proxy autodiscovery
Length: 0
Value: <MISSING>
Private/Proxy autodiscovery: [Empty]
Option: (6) Domain Name Server
Length: 4
Domain Name Server: 192.168.1.1
Option: (3) Router
Length: 4
Router: 192.168.1.1
Option: (255) End
Option End: 255
--
Conjecture is just a conclusion based on incomplete information. It isn't a fact.