Bogus routes after DHCP lease change
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| netplan |
Invalid
|
Undecided
|
Unassigned | ||
| systemd |
Unknown
|
Unknown
|
|||
| systemd (Ubuntu) |
Fix Released
|
High
|
Dan Streetman | ||
| Bionic |
Fix Released
|
High
|
Dan Streetman | ||
| Disco |
Won't Fix
|
High
|
Dan Streetman | ||
| Eoan |
Fix Released
|
High
|
Dan Streetman | ||
Bug Description
[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
On initial boot, machine got 10.0.15.109 IP address:
May 03 13:09:41 ceph2 systemd-
May 03 13:09:41 ceph2 systemd-
At one point, DHCP server reserver this IP address and client eventually picked up new IP address:
May 03 15:01:12 ceph2 systemd-
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:
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:
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
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.
| Ante Karamatić (ivoks) wrote | #1 |
| Ryan Harper (raharper) wrote | #2 |
| Changed in netplan: | |
| status: | New → Incomplete |
| Ryan Harper (raharper) wrote | #3 |
| Changed in systemd (Ubuntu): | |
| status: | New → Incomplete |
| Ante Karamatić (ivoks) wrote | #4 |
| Changed in netplan: | |
| status: | Incomplete → Invalid |
| Changed in systemd (Ubuntu): | |
| importance: | Undecided → High |
| status: | Incomplete → Triaged |
| Changed in systemd (Ubuntu): | |
| assignee: | nobody → Dan Streetman (ddstreet) |
| Changed in systemd (Ubuntu Eoan): | |
| status: | Triaged → In Progress |
| Changed in systemd (Ubuntu Disco): | |
| assignee: | nobody → Dan Streetman (ddstreet) |
| Changed in systemd (Ubuntu Bionic): | |
| assignee: | nobody → Dan Streetman (ddstreet) |
| Changed in systemd (Ubuntu Disco): | |
| importance: | Undecided → Medium |
| Changed in systemd (Ubuntu Bionic): | |
| importance: | Undecided → Medium |
| tags: | added: bionic disco eoan next-ddstreet systemd |
| tags: |
added: ddstreet removed: next-ddstreet |
| Changed in systemd (Ubuntu Disco): | |
| status: | New → In Progress |
| Changed in systemd (Ubuntu Bionic): | |
| status: | New → In Progress |
| description: | updated |
| Łukasz Zemczak (sil2100) wrote Please test proposed package | #5 |
| Changed in systemd (Ubuntu Eoan): | |
| status: | In Progress → Fix Committed |
| tags: | added: verification-needed verification-needed-eoan |
| Ubuntu SRU Bot (ubuntu-sru-bot) wrote Autopkgtest regression report (systemd/242-7ubuntu3.2) | #6 |
| Dan Streetman (ddstreet) wrote | #7 |
| tags: |
added: verification-done verification-done-eoan removed: verification-needed verification-needed-eoan |
| Launchpad Janitor (janitor) wrote | #9 |
| Changed in systemd (Ubuntu Eoan): | |
| status: | Fix Committed → Fix Released |
| Łukasz Zemczak (sil2100) wrote Update Released | #8 |
| Changed in systemd (Ubuntu Disco): | |
| importance: | Medium → High |
| Changed in systemd (Ubuntu Bionic): | |
| importance: | Medium → High |
| Dan Streetman (ddstreet) wrote | #10 |
| Changed in systemd (Ubuntu Disco): | |
| status: | In Progress → Won't Fix |
| Changed in systemd (Ubuntu): | |
| status: | In Progress → Fix Released |
| Dan Streetman (ddstreet) wrote | #11 |
| Changed in systemd (Ubuntu Bionic): | |
| status: | In Progress → Fix Released |
I forgot to mention; this puts machine in a weird state. It can be connected to, via 10.0.15.128, but it can't initiate connections to outside. By removing routes:
# ip r d default via 10.0.15.253 dev br0 proto dhcp src 10.0.15.109 metric 100
# ip r d 10.0.15.253 dev br0 proto dhcp scope link src 10.0.15.109 metric 100
machine is usable again.