IP/Network |
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DHCP IPv4
DHCP stands for Dynamic Host Configuration Protocol. For almost every data communication we commonly do with PC or Smartphone, they are all based on IP (Internet Protocol). For all IP communication, the first requirement is every device should get a specific IP address. Even until several years ago, most of these IP allocation was done manually. It means they put a specific IP (we call it static IP) into a configuration window. However, you see this process done automatically in the background. How this IP can automatically assigned ? For this automatic IP allocation, the industry came up with special protocol designed for automatic IP allocation. One of this specific IP allocation protocol is DHCP. Since we have two different types of IP, IPv4 and IPv6. We have two different type of DHCP. When we say just 'DHCP', it usually mean 'DHCP for IPv4'. In case of IPv6, we call it DHCPv6. This page is only for DHCP for IPv4. I will write separate page for IPv6.
Bootstrap Protocol (Discover) Message type: Boot Request (1) Hardware type: Ethernet (0x01) Hardware address length: 6 Hops: 0 Transaction ID: 0xff18ecc3 Seconds elapsed: 1 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: aa:bb:cc:dd:ee:ff Client hardware address padding: 00000000000000000000 Server host name not given Boot file name not given Magic cookie: DHCP Option: (53) DHCP Message Type (Discover) Length: 1 DHCP: Discover (1) Option: (61) Client identifier Length: 7 Hardware type: Ethernet (0x01) Client MAC address: aa:bb:cc:dd:ee:ff Option: (57) Maximum DHCP Message Size Length: 2 Maximum DHCP Message Size: 1500 Option: (60) Vendor class identifier Length: 12 Vendor class identifier: dhcpcd-5.5.6 Option: (12) Host Name Length: 24 Host Name: android-21b08ec0480ae8b6 Option: (55) Parameter Request List Length: 10 Parameter Request List Item: (1) Subnet Mask Parameter Request List Item: (33) Static Route Parameter Request List Item: (3) Router Parameter Request List Item: (6) Domain Name Server Parameter Request List Item: (15) Domain Name Parameter Request List Item: (26) Interface MTU Parameter Request List Item: (28) Broadcast Address Parameter Request List Item: (51) IP Address Lease Time Parameter Request List Item: (58) Renewal Time Value Parameter Request List Item: (59) Rebinding Time Value Option: (255) End Option End: 255
Bootstrap Protocol (Offer) Message type: Boot Reply (2) Hardware type: Ethernet (0x01) Hardware address length: 6 Hops: 0 Transaction ID: 0xff18ecc3 Seconds elapsed: 1 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: 192.168.0.1 (192.168.0.1) Next server IP address: 192.168.0.254 (192.168.0.254) Relay agent IP address: 0.0.0.0 (0.0.0.0) Client MAC address: aa:bb:cc:dd:ee:ff Client hardware address padding: 00000000000000000000 Server host name not given Boot file name not given Magic cookie: DHCP Option: (53) DHCP Message Type (Offer) Length: 1 DHCP: Offer (2) Option: (54) DHCP Server Identifier Length: 4 DHCP Server Identifier: 192.168.0.254 (192.168.0.254) Option: (51) IP Address Lease Time Length: 4 IP Address Lease Time: (3600s) 1 hour Option: (58) Renewal Time Value Length: 4 Renewal Time Value: (1800s) 30 minutes Option: (59) Rebinding Time Value Length: 4 Rebinding Time Value: (3200s) 53 minutes, 20 seconds Option: (1) Subnet Mask Length: 4 Subnet Mask: 255.255.255.0 (255.255.255.0) Option: (28) Broadcast Address Length: 4 Broadcast Address: 192.168.0.255 (192.168.0.255) Option: (6) Domain Name Server Length: 4 Domain Name Server: 192.168.0.254 (192.168.0.254) Option: (255) End Option End: 255 Padding
Bootstrap Protocol (Request) Message type: Boot Request (1) Hardware type: Ethernet (0x01) Hardware address length: 6 Hops: 0 Transaction ID: 0xff18ecc3 Seconds elapsed: 1 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: aa:bb:cc:dd:ee:ff Client hardware address padding: 00000000000000000000 Server host name not given Boot file name not given Magic cookie: DHCP Option: (53) DHCP Message Type (Request) Length: 1 DHCP: Request (3) Option: (61) Client identifier Length: 7 Hardware type: Ethernet (0x01) Client MAC address: aa:bb:cc:dd:ee:ff Option: (50) Requested IP Address Length: 4 Requested IP Address: 192.168.0.1 (192.168.0.1) Option: (54) DHCP Server Identifier Length: 4 DHCP Server Identifier: 192.168.0.254 (192.168.0.254) Option: (57) Maximum DHCP Message Size Length: 2 Maximum DHCP Message Size: 1500 Option: (60) Vendor class identifier Length: 12 Vendor class identifier: dhcpcd-5.5.6 Option: (12) Host Name Length: 24 Host Name: android-21b08ec0480ae8b6 Option: (55) Parameter Request List Length: 10 Parameter Request List Item: (1) Subnet Mask Parameter Request List Item: (33) Static Route Parameter Request List Item: (3) Router Parameter Request List Item: (6) Domain Name Server Parameter Request List Item: (15) Domain Name Parameter Request List Item: (26) Interface MTU Parameter Request List Item: (28) Broadcast Address Parameter Request List Item: (51) IP Address Lease Time Parameter Request List Item: (58) Renewal Time Value Parameter Request List Item: (59) Rebinding Time Value Option: (255) End Option End: 255
Bootstrap Protocol (ACK) Message type: Boot Reply (2) Hardware type: Ethernet (0x01) Hardware address length: 6 Hops: 0 Transaction ID: 0xff18ecc3 Seconds elapsed: 1 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: 192.168.0.1 (192.168.0.1) Next server IP address: 192.168.0.254 (192.168.0.254) Relay agent IP address: 0.0.0.0 (0.0.0.0) Client MAC address: aa:bb:cc:dd:ee:ff 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: 192.168.0.254 (192.168.0.254) Option: (51) IP Address Lease Time Length: 4 IP Address Lease Time: (3600s) 1 hour Option: (58) Renewal Time Value Length: 4 Renewal Time Value: (1800s) 30 minutes Option: (59) Rebinding Time Value Length: 4 Rebinding Time Value: (3200s) 53 minutes, 20 seconds Option: (1) Subnet Mask Length: 4 Subnet Mask: 255.255.255.0 (255.255.255.0) Option: (28) Broadcast Address Length: 4 Broadcast Address: 192.168.0.255 (192.168.0.255) Option: (6) Domain Name Server Length: 4 Domain Name Server: 192.168.0.254 (192.168.0.254) Option: (255) End Option End: 255 Padding
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