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Ceci est une ancienne révision du document !

Table des matières

Les clients DHCP

Sur Debian 12 (Bookworm), le client dhcp installé par défaut est le client d'isc: isc-dhcp-client. Ce client dispose d'un fichier de configuration /etc/dhcp/dhclient.conf. Comparons les configurations sur «nas» et «democlient1»

Configuration

nas

Version expurgée des commentaires: 

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;

send host-name = gethostname();
request subnet-mask, broadcast-address, time-offset, routers,
        domain-name, domain-name-servers, domain-search, host-name,
        dhcp6.name-servers, dhcp6.domain-search, dhcp6.fqdn, dhcp6.sntp-servers,
        netbios-name-servers, netbios-scope, interface-mtu,
        rfc3442-classless-static-routes, ntp-servers;
Ce fichier n'a pas été modifié, c'est donc la configuration par défaut.

Toutes les options en gras sont inutiles dans notre contexte. Elles ont été supprimées dans le fichier de configuration sur «democlient1»

democlient1

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;

send host-name = gethostname();
request subnet-mask, broadcast-address, time-offset, routers,
        domain-name, domain-name-servers, domain-search,
        rfc3442-classless-static-routes, ntp-servers;

send dhcp-client-identifier 1:52:54:00:b7:66:81;
En revanche, ici le client envoie explicitement sa seule adresse MAC comme CID, ce qui explique l'apparente anomalie constatée page précédente.

La mémoire du client

isc-dhcp-client a de la mémoire. Elle est écrite dans le fichier /var/lib/dhcp/dhclient.enp1s0.leases. Voyons la mémoire du nas: 

cat dhclient.enp1s0.leases 
default-duid "\000\001\000\001/qNjRT\000\322\232\016";
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 11:04:54;
  rebind 6 2025/03/22 11:20:11;
  expire 6 2025/03/22 11:35:11;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 11:29:41;
  rebind 6 2025/03/22 11:49:54;
  expire 6 2025/03/22 12:04:54;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 11:54:35;
  rebind 6 2025/03/22 12:14:41;
  expire 6 2025/03/22 12:29:41;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 12:21:31;
  rebind 6 2025/03/22 12:39:35;
  expire 6 2025/03/22 12:54:35;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 12:46:46;
  rebind 6 2025/03/22 13:06:31;
  expire 6 2025/03/22 13:21:31;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 13:14:36;
  rebind 6 2025/03/22 13:31:46;
  expire 6 2025/03/22 13:46:46;
}





lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 14:18:47;
  rebind 6 2025/03/22 14:38:28;
  expire 6 2025/03/22 14:53:28;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 14:48:17;
  rebind 6 2025/03/22 15:03:47;
  expire 6 2025/03/22 15:18:47;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 15:13:52;
  rebind 6 2025/03/22 15:33:17;
  expire 6 2025/03/22 15:48:17;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 15:40:37;
  rebind 6 2025/03/22 15:58:52;
  expire 6 2025/03/22 16:13:52;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 16:06:35;
  rebind 6 2025/03/22 16:25:37;
  expire 6 2025/03/22 16:40:37;
}
lease {
  interface "enp1s0";
  fixed-address 192.168.61.2;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 3600;
  option routers 192.168.61.1;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.61.1;
  option domain-name-servers 192.168.61.1;
  option domain-search "home.nain-t.net.";
  option dhcp-renewal-time 1800;
  option dhcp-rebinding-time 2700;
  option host-name "nas";
  option dhcp-client-identifier ff:0:d2:9a:e:0:1:0:1:2f:71:4e:6a:52:54:0:d2:9a:e;
  renew 6 2025/03/22 16:29:12;
  rebind 6 2025/03/22 16:51:35;
  expire 6 2025/03/22 17:06:35;
}

Le client DHCP d'ISC: Dernière modification le: 22/03/2025 à 16:23 par prof