On 12/02/2025 17:16, jean-christophe manciot wrote: > Now, if I add dhcp-range option, for instance: > dhcp-range=192.168.0.50,192.168.0.150,12h > > DHCP ports are open on **all** interfaces instead of just lo as specified > earlier: > /usr/bin/netstat -tunpevaW | grep dnsmasq > udp 0 0 0.0.0.0:67 0.0.0.0:* > 0 7411150 2807884/dnsmasq > udp 0 0 127.0.0.1:69 0.0.0.0:* > 0 7411153 2807884/dnsmasq > udp6 0 0 ::1:69 :::* > 0 7411154 2807884/dnsmasq >
That's as designed. To do DHCP successfully dnsmasq needs to get all packets. It will ignore packets arriving from interfaces it's not configured for. (You're unlikely to be able to do DHCP on the loopback interface, and certainly not with that dhcp-range. The only time when a DHCP server can do something sensible with packets arriving on lo is when there's a DHCP relay in use on the same machine, and that's pretty esoteric. Simon. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to dnsmasq in Ubuntu. https://bugs.launchpad.net/bugs/2098119 Title: dnsmasq opens DHCP server ports on all interfaces instead of just on the interface(s) defined in interface= setting Status in dnsmasq package in Ubuntu: New Bug description: ubuntu oracular linux 6.12.0-15-generic dnsmasq 2.90-4 With the following specific configuration in /etc/dnsmasq.conf (due to interference with another DNS server): port=0 The systemd service starts: # echo 'q' | sudo systemctl --no-pager --full status dnsmasq ● dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server Loaded: loaded (/usr/lib/systemd/system/dnsmasq.service; enabled; preset: enabled) Active: active (running) since Wed 2025-02-12 17:31:55 CET; 1min 24s ago Invocation: 3aa94eb3e49c40e8b7cc53f316cc90eb Main PID: 1550822 (dnsmasq) Tasks: 1 (limit: 36889) Memory: 844K (peak: 2.4M) CPU: 28ms CGroup: /system.slice/dnsmasq.service └─1550822 /usr/sbin/dnsmasq -x /run/dnsmasq/dnsmasq.pid -u dnsmasq -7 /etc/dnsmasq.d,.dpkg-dist,.dpkg-old,.dpkg-new --local-service --trust-anchor=.,20326,8,2,e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d Feb 12 17:31:55 samsung9-ubuntux systemd[1]: Starting dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server... Feb 12 17:31:55 samsung9-ubuntux dnsmasq[1550822]: started, version 2.90 DNS disabled Feb 12 17:31:55 samsung9-ubuntux dnsmasq[1550822]: compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset nftset auth cryptohash DNSSEC loop-detect inotify dumpfile Feb 12 17:31:55 samsung9-ubuntux systemd[1]: Started dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server. but there is no DHCP server port open: # /usr/bin/netstat -tunpevaW | grep dnsmasq # /usr/bin/netstat -tunpevaW | grep :67 # It does not change anything if I specify 'interface=eth0' or 'listen-address=127.0.0.1' for instance. It does not change anything either if I specify a specific DNS port other than 53 with 'port=663' for instance: still no DHCP server port open by dnsmasq. Everything works fine with TFTP though with: listen-address=127.0.0.1 bind-interfaces enable-tftp # /usr/bin/netstat -tunpevaW | grep dnsmasq udp 0 0 127.0.0.1:69 0.0.0.0:* 0 5781084 2183724/dnsmasq To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/2098119/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
