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Description of problem: local-address 10.0.0.1; setting in /etc/dhcp/dhcpd.conf makes the dhcpd service listen on 10.0.0.1:67 but the raw socket still listens on all interfaces. Version-Release number of selected component (if applicable): isc-dhcpd-4.3.6 How reproducible: Install F27 Install dhcpd Use this config file: option domain-name "lajoie.org"; local-address 10.0.0.1; option domain-name-servers 10.0.0.1; default-lease-time 600; max-lease-time 7200; authoritative; subnet 10.0.0.0 netmask 255.255.255.0 { range dynamic-bootp 10.0.0.100 10.0.0.254; option broadcast-address 10.0.0.255; option routers 10.0.0.1; option interface-mtu 1452; } Steps to Reproduce: 1. systemctl enable dhcpd.service 2. systemctl start dhcpd.service 3. ss -4lnp | grep dhcpd Actual results: raw UNCONN 0 0 0.0.0.0:1 udp UNCONN 12183 0 10.0.0.1:67 Expected results: raw UNCONN 0 0 10.0.0.1:1 udp UNCONN 12183 0 10.0.0.1:67 Additional info: The raw socket should only listen off the interface which DHCPD is serving.
Hi Eric! This is not actually a problem. DHCPd *should* be listening to the "all balls" address because the daemon needs direct, unrestricted access to the packets on the network. If the raw socket is bound to a particular IP, the kernel may (or may not) limit which packets are presented to the daemon. DHCPd very quickly examines and discards any packets that it does not need to process when packets are received. Without listening on 0.0.0.0, packets from unconfigured or partially configured clients may not be exposed to DHCPd, breaking the functionality of the service. If you need to prevent DHCPd from listening to 0.0.0.0, you can compile the software to no use raw sockets, but you will need a DHCP relay that does use raw sockets to proxy the packets to/from the clients. See also : https://kb.isc.org/docs/aa-00379 -Rich Alloway (Rogue Wave)
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Fedora 27 changed to end-of-life (EOL) status on 2018-11-30. Fedora 27 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. If you are unable to reopen this bug, please file a new report against the current release. If you experience problems, please add a comment to this bug. Thank you for reporting this bug and we are sorry it could not be fixed.