Add DHCP options while the ESP is requesting a server #8223
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DHCP client is configured there. Do you think you could propose a pull request on this repository ? |
d-a-v
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@d-a-v I can try. |
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Basic Infos
Platform
Settings in IDE
Problem Description
The ESP8266 is not sending the Client Identifier when it request a DHCP server.
Some routers-gateway-dhcp require this option to register the ESP's hostname into their DNS.
On devices with several network interfaces it prevents the DHCP to assign an new address per interface.
Can we amend the Client Identifier (option 61) to the DHCP query?
MCVE Sketch
// cf https://github.com/esp8266/Arduino/blob/master/libraries/ESP8266mDNS/examples/mDNS_Web_Server/mDNS_Web_Server.inoDebug Messages
VERSUS a right DHCP request:
me@ime /Users/me sudo dhcpdump -i en0 TIME: 2021-07-18 00:36:27.113 IP: 0.0.0.0 (98:1:a7:ZZ:ZZ:ZZ) > 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: 7519ZZZZ SECS: 0 FLAGS: 0 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 98:01:a7:ZZ:ZZ:ZZ:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 3 (DHCPREQUEST) OPTION: 55 ( 11) Parameter Request List 1 (Subnet mask) 121 (Classless Static Route) 3 (Routers) 6 (DNS server) 15 (Domainname) 114 (URL) 119 (Domain Search) 252 (MSFT - WinSock Proxy Auto Detect) 95 (LDAP) 44 (NetBIOS name server) 46 (NetBIOS node type) OPTION: 57 ( 2) Maximum DHCP message size 1500 OPTION: 61 ( 7) Client-identifier 01:98:01:a7:ZZ:ZZ:ZZ OPTION: 50 ( 4) Request IP address 192.168.1.11 OPTION: 51 ( 4) IP address leasetime 7776000 (12w6d) OPTION: 12 ( 3) Host name iMe --------------------------------------------------------------------------- TIME: 2021-07-18 00:36:28.529 IP: 0.0.0.0 (98:1:a7:ZZ:ZZ:ZZ) > 255.255.255.255 (ff:ff:ff:ff:ff:ff) OP: 1 (BOOTPREQUEST) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: 7519ZZZZ SECS: 1 FLAGS: 0 CIADDR: 0.0.0.0 YIADDR: 0.0.0.0 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 98:01:a7:ZZ:ZZ:ZZ:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 3 (DHCPREQUEST) OPTION: 55 ( 11) Parameter Request List 1 (Subnet mask) 121 (Classless Static Route) 3 (Routers) 6 (DNS server) 15 (Domainname) 114 (URL) 119 (Domain Search) 252 (MSFT - WinSock Proxy Auto Detect) 95 (LDAP) 44 (NetBIOS name server) 46 (NetBIOS node type) OPTION: 57 ( 2) Maximum DHCP message size 1500 OPTION: 61 ( 7) Client-identifier 01:98:01:a7:ZZ:ZZ:ZZ OPTION: 50 ( 4) Request IP address 192.168.1.11 OPTION: 51 ( 4) IP address leasetime 7776000 (12w6d) OPTION: 12 ( 3) Host name iMe --------------------------------------------------------------------------- TIME: 2021-07-18 00:36:28.634 IP: 192.168.1.254 (0:24:d4:ZZ:ZZ:ZZ) > 192.168.1.11 (98:1:a7:ZZ:ZZ:ZZ) OP: 2 (BOOTPREPLY) HTYPE: 1 (Ethernet) HLEN: 6 HOPS: 0 XID: 75198106 SECS: 0 FLAGS: 0 CIADDR: 0.0.0.0 YIADDR: 192.168.1.11 SIADDR: 0.0.0.0 GIADDR: 0.0.0.0 CHADDR: 98:01:a7:ZZ:ZZ:ZZ:00:00:00:00:00:00:00:00:00:00 SNAME: . FNAME: . OPTION: 53 ( 1) DHCP message type 5 (DHCPACK) OPTION: 54 ( 4) Server identifier 192.168.1.254 OPTION: 51 ( 4) IP address leasetime 864000 (1w3d) OPTION: 1 ( 4) Subnet mask 255.255.255.0 OPTION: 3 ( 4) Routers 192.168.1.254 OPTION: 6 ( 8) DNS server 212.27.888.888,212.27.888.888 ---------------------------------------------------------------------------As you can see, the default Client Identifier is:
OPTION: 61 ( 7) Client-identifier 01:{{macAddress}}
And the field should be optional:
https://datatracker.ietf.org/doc/html/rfc4361
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