[Bug 1833193] Re: systemd-networkd fails to apply static IPv4 when the static IP is the same as previously configured by DHCP
Dan Streetman
ddstreet at canonical.com
Thu Dec 12 22:34:58 UTC 2019
** Description changed:
- In bionic, running systemd 237-3ubuntu10.22 and netplan.io
- 0.97-0ubuntu1~18.04.1, systemd-networkd fails to configure an interface
- with a static IPv4 address if the statically confiugred address is the
- same as the interface already has gotten from DHCP.
+ [impact]
+
+ if networkd is configured with a static address, and the address has
+ already been assigned by dhcp (so that it has finite valid_lft),
+ networkd will not change the valid_lft to 'forever' during startup,
+ which leaves networkd thinking the address is static (meaning, networkd
+ will not attempt to renew the dhcp lease) but the address valid_lft
+ counting down.
+
+ Once the valid_lft expires, the kernel will remove the address from the
+ interface, breaking the system's networking.
+
+ [test case]
+
+ configure a system with networkd similar to:
+
+ [Match]
+ Name=ens3
+
+ [Network]
+ DHCP=ipv4
+
+ restart systemd-networkd, and ens3 should get a DHCP address, e.g.:
+
+ $ ip -4 a show ens3
+ 2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
+ inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
+ valid_lft 2295sec preferred_lft 2295sec
+
+ then, edit the networkd config to use a static address, e.g.:
+
+ [Match]
+ Name=ens3
+
+ [Network]
+ Address=192.168.122.147/24
+ Gateway=192.168.122.1
+ DNS=192.168.122.1
+ Domains=vm
+
+ make sure to use the exact same address that was provided by dhcp.
+
+ Then, without rebooting, just restart networkd and check the address
+ lft:
+
+ $ sudo systemctl restart systemd-networkd
+
+ $ ip -4 a show ens3
+ 2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
+ inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
+ valid_lft 2992sec preferred_lft 2992sec
+
+
+ the address should have 'forever' valid_lft, but it doesn't.
+
+ [regression potential]
+
+ this changes the details of how networkd updates static addresses during
+ startup, so any regression would occur at networkd startup when using
+ static addresses.
+
+ [scope]
+
+ this is needed only in Bionic and Disco.
+
+ this is fixed by upstream:
+ https://github.com/systemd/systemd/pull/11460/commits
+ specifically commit a47a6daebe0af26c07d8d423225eb4add110793c
+ which is included in Eoan and later.
+
+ In Xenial using networkd, testing shows this problem does not occur.
+
+ [other info]
+
+ original description:
+ ---
+
+
+ In bionic, running systemd 237-3ubuntu10.22 and netplan.io 0.97-0ubuntu1~18.04.1, systemd-networkd fails to configure an interface with a static IPv4 address if the statically confiugred address is the same as the interface already has gotten from DHCP.
This will cause the interface to loose its IP address when the DHCP
lease exires, even though you've told netplan to configure it as static.
I expect systemd-networkd to actually configure an IP address as static,
regardless of what address the interface has before from DHCP.
# lsb_release -rd
Description: Ubuntu 18.04.2 LTS
Release: 18.04
# apt-cache policy systemd
systemd:
- Installed: 237-3ubuntu10.22
+ Installed: 237-3ubuntu10.22
# apt-cache policy netplan.io
netplan.io:
- Installed: 0.97-0ubuntu1~18.04.1
+ Installed: 0.97-0ubuntu1~18.04.1
A paste of systemd-networkd's debug log when I run "netplan apply" and
the interface already has the static IP configured from DHCP.
It seems like upon a restart, systemd-networkd will allways add whatever
IP config it had before the service stopped, and then apply changes (if
any). Since my new config has the same IP as it already had, it does
nothing even though the new config has static configuration.
** Description changed:
[impact]
if networkd is configured with a static address, and the address has
already been assigned by dhcp (so that it has finite valid_lft),
networkd will not change the valid_lft to 'forever' during startup,
which leaves networkd thinking the address is static (meaning, networkd
will not attempt to renew the dhcp lease) but the address valid_lft
counting down.
Once the valid_lft expires, the kernel will remove the address from the
interface, breaking the system's networking.
[test case]
configure a system with networkd similar to:
[Match]
Name=ens3
[Network]
DHCP=ipv4
restart systemd-networkd, and ens3 should get a DHCP address, e.g.:
$ ip -4 a show ens3
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
- inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
- valid_lft 2295sec preferred_lft 2295sec
+ inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
+ valid_lft 2295sec preferred_lft 2295sec
then, edit the networkd config to use a static address, e.g.:
[Match]
Name=ens3
[Network]
Address=192.168.122.147/24
Gateway=192.168.122.1
DNS=192.168.122.1
Domains=vm
make sure to use the exact same address that was provided by dhcp.
Then, without rebooting, just restart networkd and check the address
lft:
$ sudo systemctl restart systemd-networkd
$ ip -4 a show ens3
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
- inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
- valid_lft 2992sec preferred_lft 2992sec
-
+ inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
+ valid_lft 2992sec preferred_lft 2992sec
the address should have 'forever' valid_lft, but it doesn't.
[regression potential]
this changes the details of how networkd updates static addresses during
startup, so any regression would occur at networkd startup when using
static addresses.
[scope]
this is needed only in Bionic and Disco.
this is fixed by upstream:
https://github.com/systemd/systemd/pull/11460/commits
specifically commit a47a6daebe0af26c07d8d423225eb4add110793c
which is included in Eoan and later.
- In Xenial using networkd, testing shows this problem does not occur.
+ In Xenial using networkd, testing shows this problem does not occur,
+ because this older version of networkd removes the 'foreign' dhcp
+ address before re-assigning it as a static address.
[other info]
original description:
---
-
- In bionic, running systemd 237-3ubuntu10.22 and netplan.io 0.97-0ubuntu1~18.04.1, systemd-networkd fails to configure an interface with a static IPv4 address if the statically confiugred address is the same as the interface already has gotten from DHCP.
+ In bionic, running systemd 237-3ubuntu10.22 and netplan.io
+ 0.97-0ubuntu1~18.04.1, systemd-networkd fails to configure an interface
+ with a static IPv4 address if the statically confiugred address is the
+ same as the interface already has gotten from DHCP.
This will cause the interface to loose its IP address when the DHCP
lease exires, even though you've told netplan to configure it as static.
I expect systemd-networkd to actually configure an IP address as static,
regardless of what address the interface has before from DHCP.
# lsb_release -rd
Description: Ubuntu 18.04.2 LTS
Release: 18.04
# apt-cache policy systemd
systemd:
Installed: 237-3ubuntu10.22
# apt-cache policy netplan.io
netplan.io:
Installed: 0.97-0ubuntu1~18.04.1
A paste of systemd-networkd's debug log when I run "netplan apply" and
the interface already has the static IP configured from DHCP.
It seems like upon a restart, systemd-networkd will allways add whatever
IP config it had before the service stopped, and then apply changes (if
any). Since my new config has the same IP as it already had, it does
nothing even though the new config has static configuration.
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https://bugs.launchpad.net/bugs/1833193
Title:
systemd-networkd fails to apply static IPv4 when the static IP is the
same as previously configured by DHCP
Status in systemd:
Fix Released
Status in systemd package in Ubuntu:
Fix Released
Status in systemd source package in Bionic:
In Progress
Status in systemd source package in Disco:
In Progress
Bug description:
[impact]
if networkd is configured with a static address, and the address has
already been assigned by dhcp (so that it has finite valid_lft),
networkd will not change the valid_lft to 'forever' during startup,
which leaves networkd thinking the address is static (meaning,
networkd will not attempt to renew the dhcp lease) but the address
valid_lft counting down.
Once the valid_lft expires, the kernel will remove the address from
the interface, breaking the system's networking.
[test case]
configure a system with networkd similar to:
[Match]
Name=ens3
[Network]
DHCP=ipv4
restart systemd-networkd, and ens3 should get a DHCP address, e.g.:
$ ip -4 a show ens3
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
valid_lft 2295sec preferred_lft 2295sec
then, edit the networkd config to use a static address, e.g.:
[Match]
Name=ens3
[Network]
Address=192.168.122.147/24
Gateway=192.168.122.1
DNS=192.168.122.1
Domains=vm
make sure to use the exact same address that was provided by dhcp.
Then, without rebooting, just restart networkd and check the address
lft:
$ sudo systemctl restart systemd-networkd
$ ip -4 a show ens3
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic ens3
valid_lft 2992sec preferred_lft 2992sec
the address should have 'forever' valid_lft, but it doesn't.
[regression potential]
this changes the details of how networkd updates static addresses
during startup, so any regression would occur at networkd startup when
using static addresses.
[scope]
this is needed only in Bionic and Disco.
this is fixed by upstream:
https://github.com/systemd/systemd/pull/11460/commits
specifically commit a47a6daebe0af26c07d8d423225eb4add110793c
which is included in Eoan and later.
In Xenial using networkd, testing shows this problem does not occur,
because this older version of networkd removes the 'foreign' dhcp
address before re-assigning it as a static address.
[other info]
original description:
---
In bionic, running systemd 237-3ubuntu10.22 and netplan.io
0.97-0ubuntu1~18.04.1, systemd-networkd fails to configure an
interface with a static IPv4 address if the statically confiugred
address is the same as the interface already has gotten from DHCP.
This will cause the interface to loose its IP address when the DHCP
lease exires, even though you've told netplan to configure it as
static.
I expect systemd-networkd to actually configure an IP address as
static, regardless of what address the interface has before from DHCP.
# lsb_release -rd
Description: Ubuntu 18.04.2 LTS
Release: 18.04
# apt-cache policy systemd
systemd:
Installed: 237-3ubuntu10.22
# apt-cache policy netplan.io
netplan.io:
Installed: 0.97-0ubuntu1~18.04.1
A paste of systemd-networkd's debug log when I run "netplan apply" and
the interface already has the static IP configured from DHCP.
It seems like upon a restart, systemd-networkd will allways add
whatever IP config it had before the service stopped, and then apply
changes (if any). Since my new config has the same IP as it already
had, it does nothing even though the new config has static
configuration.
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