With the following setup: port=0 interface=eth0 bind-interfaces dhcp-range=192.168.1.2,192.168.1.254
I get: # /usr/bin/netstat -tunpevaW | grep dnsmasq udp 0 0 0.0.0.0:67 0.0.0.0:* 0 19371604 3877093/dnsmasq which contradicts your own documentation (please read until the end): # If you want dnsmasq to listen for DHCP and DNS requests only on # specified interfaces (and the loopback) give the name of the # interface (eg eth0) here. # Repeat the line for more than one interface. # interface= # On systems which support it, dnsmasq binds the wildcard address, # even when it is listening on only some interfaces. It then discards # requests that it shouldn't reply to. This has the advantage of # working even when interfaces come and go and change address. If you # want dnsmasq to really bind only the interfaces it is listening on, # uncomment this option. About the only time you may need this is when # running another nameserver on the same machine. # bind-interfaces So, bind-interfaces is not applied. Why is it a problem? In cases where there are multiple DHCP servers, this dnsmasq issue prevents the coexistence with these other servers as it binds to **all** ionterfaces and prevent other servers from listening on the interfaces they were setup for. A perfect example is libvirtd: this issue prevents libvirtd from starting its one instance of dnsmasq over virbr0 (for instance). Cf. https://wiki.libvirt.org/Libvirtd_and_dnsmasq.html. FYI, this failed behavior did not exist in Ubuntu noble. -- 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
