Dernière version du 10 août 2023 à 20:37

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Installation

sudo pacman dnsmasq

Configuration DNS

/etc/dnsmasq.conf

# ip du serveur
listen-address=::1, 127.0.0.1, 192.168.0.x

# définit la route par défaut si ce n'est pas celle du serveur dnsmasq
dhcp-option=option:router,192.168.0.y

# Associer un domaine à une adresse IP
address=/mon-domaine.fr/192.168.0.10

# ignore /etc/resolv.conf if there is only localhost
no-resolv
# ignore /etc/hosts if there is only localhost
no-hosts
# Upstream DNS server addresses (serveur DNS de la box)
server=192.168.0.x

/etc/resolv.conf

nameserver ::1
nameserver 127.0.0.1

/etc/hosts

#<ip-address>	<hostname.domain.org>   <hostname>
127.0.0.1                               localhost
::1                                     localhost

192.168.0.x     mabox
192.168.0.y     site1.domaine.net site2.domaine.net
192.168.0.z     site3 site4

NetworkManager

Restart of NetworkManager overwrite the /etc/resolv.conf file.

/etc/NetworkManager/NetworkManager.conf

[main]
# add the following line to avoid NetworkManager to change the resolv.conf file
dns=none

DHCPCD

/etc/dhcpcd.conf

# dhcpcd, unfortunately, tends to overwrite /etc/resolv.conf by default,
# so if you use DHCP it is a good idea to protect /etc/resolv.conf. 
nohook resolv.conf

Configuration DHCP

/etc/dnsmasq.conf

interface=eth0
bind-interfaces

# allouer dynamique les ip 192.168.0.50 à 192.168.0.150
dhcp-range=192.168.0.50,192.168.0.150,12h
# pas d'allocations dynamique, seul les allocations statiques sont autorisées
dhcp-range=192.168.0.0,static

# Baux DHCP statiques
# donne un nom et une ip à l'adresse MAC correspondante
dhcp-host=xx:xx:xx:xx:xx:xx,Nom,192.168.x.x,infinite
# donne une ip à la machine dont le nom correspond
dhcp-host=Nom,192.168.x.x,infinite

# si unique serveur DHCP
dhcp-authoritative

Afficher les baux dhcp en cours

cat /var/lib/misc/dnsmasq.leases

Mettre fin à un bail

systemctl stop dnsmasq

# supprimer la ligne correspondant au bail
nano /var/lib/misc/dnsmasq.leases

systemctl start dnsmasq

# restart the client to get a new ip adress
sc-restart dhcpcd@eth0

VPN

/etc/dnsmasq.conf

interface=eth0
# ajouter l'interface tun
interface=tun0

# ajouter l'ip du serveur sur le réseau VPN
listen-address=127.0.0.1, 10.8.0.1

bind-interfaces

failed to create listening socket for 10.8.0.1: Cannot assign requested address

Dnsmasq démarre avant qu'OpenVPN n'ai eu le temp d'enregistrer l'ip 10.8.0.1
Étendre la configuration du service dnsmasq sans écraser la configuration par défaut: /usr/lib/systemd/system/dnsmasq.service

/etc/systemd/system/dnsmasq.service.d/openvpn.conf

[Unit]
After=openvpn@server.service

Firewall

# allow incoming communication on port 53 with protocol tcp and udp
sudo ufw allow 53 comment 'DNS tcp/udp port 53'

sudo ufw allow 67,68/udp comment 'DHCP udp ports 67,68'

UFW DNSmasq application

log

/var/log/messages.log

/etc/dnsmasq.conf

# For debugging purposes, log each DNS query as it passes through dnsmasq.
log-queries
# Log lots of extra information about DHCP transactions.
log-dhcp

Erreurs

Temporary failure in name resolution

cron reboot

crontab

# restart dnsmasq 60 seconds after reboot
@reboot sleep 60 && systemctl restart dnsmasq

dnsmasq.service

bug

Dnsmasq fails to respond on network devices that weren't up when its service started, thus not binding as expected.
Fix: delay startup until after the network is online.

/lib/systemd/system/dnsmasq.service

[Unit]
#Requires=network.target
#After=network.target
Requires=network-online.target
After=network-online.target

failed to create listening socket for port 53: Address already in use

Un autre programme utilise déjà le port 53.

sudo netstat -peanut | grep :53
# tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      102        16584      2147/systemd-resolv 
# udp        0      0 127.0.0.53:53           0.0.0.0:*                           102        16583      2147/systemd-resolv

Arrêter systemd-resolved (Ubuntu 18.04)

sc-stop systemd-resolved
sc-disable systemd-resolved

# supprimer le lien symbolique /etc/resolv.conf
ls -lh /etc/resolv.conf
# /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf
sudo rm /etc/resolv.conf

/etc/resolv.conf

nameserver 127.0.0.1

Modifier resolved.conf

/etc/systemd/resolved.conf

[Resolve]
DNS=127.0.0.1
DNSStubListener=no

/etc/resolv.conf

nameserver  127.0.0.1

sc-restart systemd-resolved
sc-start dnsmasq

Ne fonctionne pas avec Android

Android fait des requêtes DNS IPv6 et n'utilise donc pas DNSmasq.
Utiliser une application de changement d'adresse DNS.