** Description changed: + [impact] + + networkd does not remove old route(s) after DHCP address change + + [test case] + + on a system using networkd, that is connected to a network where you can + control the addresses that the DHCP server provides, setup system with + networkd to get address via DHCP, e.g. + + [Match] + Name=ens3 + + [Network] + DHCP=ipv4 + + + (re)start networkd or reboot, so the system gets an ipv4 DHCP address, and corresponding route to the gateway. + + + Then on the dhcp server, change the subnet to a different subnet. On the client, once its renews its DHCP address, the server will provide a new address in the new subnet, and the client will add a new default route to the new gateway address. However, the old default route to the old gateway address isn't removed. + + Note this also happens without changing the entire subnet, but is more + subtle as shown in the original description. + + [regression potential] + + this affects how networkd handles routes, so has the potential to leave + a system with partial or incorrect networking, or no networking at all. + Any regression would most likely occur during networkd (re)start or + during renewal of a DHCP lease, or when an interface is brought up. + + [other info] + + original description: + --- + + Netplan config: network: - version: 2 - renderer: networkd - ethernets: - eno4: - dhcp4: no - eno1np0: - dhcp4: no - addresses: - - 172.16.0.2/24 - bridges: - br0: - dhcp4: yes - interfaces: - - eno4 + version: 2 + renderer: networkd + ethernets: + eno4: + dhcp4: no + eno1np0: + dhcp4: no + addresses: + - 172.16.0.2/24 + bridges: + br0: + dhcp4: yes + interfaces: + - eno4 On initial boot, machine got 10.0.15.109 IP address: May 03 13:09:41 ceph2 systemd-networkd[29349]: br0: Configured May 03 13:09:41 ceph2 systemd-networkd[29349]: br0: DHCPv4 address 10.0.15.109/23 via 10.0.15.253 At one point, DHCP server reserver this IP address and client eventually picked up new IP address: May 03 15:01:12 ceph2 systemd-networkd[1137]: br0: DHCPv4 address 10.0.15.128/23 via 10.0.15.253 This resulted in IP addresses: # ip -o a 1: lo inet 127.0.0.1/8 scope host lo\ valid_lft forever preferred_lft forever 1: lo inet6 ::1/128 scope host \ valid_lft forever preferred_lft forever 2: eno1np0 inet 172.16.0.2/24 brd 172.16.0.255 scope global eno1np0\ valid_lft forever preferred_lft forever 2: eno1np0 inet6 fe80::b226:28ff:fe53:56be/64 scope link \ valid_lft forever preferred_lft forever 6: br0 inet 10.0.15.128/23 brd 10.0.15.255 scope global dynamic br0\ valid_lft 503sec preferred_lft 503sec 6: br0 inet6 fe80::b8d7:5eff:fe6b:62a/64 scope link \ valid_lft forever preferred_lft forever So far, everything is fine. But, the routes on the machine are bogus: # ip r - default via 10.0.15.253 dev br0 proto dhcp src 10.0.15.109 metric 100 - default via 10.0.15.253 dev br0 proto dhcp src 10.0.15.128 metric 100 - 10.0.14.0/23 dev br0 proto kernel scope link src 10.0.15.128 - 10.0.15.253 dev br0 proto dhcp scope link src 10.0.15.109 metric 100 - 10.0.15.253 dev br0 proto dhcp scope link src 10.0.15.128 metric 100 - 172.16.0.0/24 dev eno1np0 proto kernel scope link src 172.16.0.2 + default via 10.0.15.253 dev br0 proto dhcp src 10.0.15.109 metric 100 + default via 10.0.15.253 dev br0 proto dhcp src 10.0.15.128 metric 100 + 10.0.14.0/23 dev br0 proto kernel scope link src 10.0.15.128 + 10.0.15.253 dev br0 proto dhcp scope link src 10.0.15.109 metric 100 + 10.0.15.253 dev br0 proto dhcp scope link src 10.0.15.128 metric 100 + 172.16.0.0/24 dev eno1np0 proto kernel scope link src 172.16.0.2 routes with src 10.0.15.109 should have been removed when lease was renewed. I'm not sure if this is a bug in netplan or systemd. This is 18.04, systemd 37-3ubuntu10.21, netplan 0.40.1~18.04.4.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1831787 Title: Bogus routes after DHCP lease change To manage notifications about this bug go to: https://bugs.launchpad.net/netplan/+bug/1831787/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
