** Description changed:
- Hi there,
- we found a replicable issue that involves the Ubuntu Core networking and
causes complete loss of connectivity.
+
+ [Impact]
+
+ * networkd fails to renew a lease, specifically it fails to change IPv4
address via DHCP renew/rebind.
+ * networkd relies on a kernel feature to promote secondary IPv4 address to
primary, upon primary address lease expiry.
+ * this sysctl tunable was not enabled by default in systemd.
+
+ [Test Case]
+
+ Add a device, and assign two IPv4 addresses. First one, with a short
+ lease time. Second one, with a different ip and a longer lease time.
+ Second one should be treated as secondary ip address, and upon expiry of
+ the first one, should be promoted and become primary ip address. The
+ below scripted instructions simulate this:
+
+ sudo ip link add name testleases type dummy
+
+ sudo ip address add 192.0.2.10/27 dev testleases \
+ valid_lft 5 preferred_lft 5
+
+ sudo ip address add 192.0.2.11/27 dev testleases \
+ valid_lft 11 preferred_lft 11
+
+ ip address list dev testleases | \
+ grep -q 'inet 192.0.2.10/27 scope global dynamic testleases' \
+ && echo ok || echo not ok
+
+ ip address list dev testleases | \
+ grep -q 'inet 192.0.2.11/27 scope global secondary dynamic testleases' \
+ && echo ok || echo not ok
+
+ sleep 6
+
+ ip address list dev testleases | \
+ grep -q 'inet 192.0.2.11/27 scope global dynamic testleases' \
+ && echo ok || echo not ok
+
+ sudo ip link del dev testleases
+
+ [Regression Potential]
+
+ * This changes the default kernel behaviour, previously upon expiry of
+ the primary address, secondary addresses were removed as well. Which is
+ imho silly.
+
+ * comparing networkd renewal with isc-dhcp renewal the semantics are
+ quite different. Upon acquiring new ip address, isc-dhcp would instantly
+ flush existing ip address, and add a new one. Networkd add the new
+ address as secondary, and waits for old one to expire first before
+ promoting / switching to using the new ip address. IMHO kernel should
+ have an API to promote secondary ip address to a primary one.
+
+ * This update also applies other safe-looking options, which are
+ currently also already applied via sysctls shipped in other packages
+
+ # Source route verification
+ net.ipv4.conf.default.rp_filter = 1
+ net.ipv4.conf.all.rp_filter = 1
+
+ # Do not accept source routing
+ net.ipv4.conf.default.accept_source_route = 0
+ net.ipv4.conf.all.accept_source_route = 0
+
+ # Enable hard and soft link protection
+ fs.protected_hardlinks = 1
+ fs.protected_symlinks = 1
+
+ * This update also applies the following upstream/bufferbloat.net
+ recommended setting
+
+ # Fair Queue CoDel packet scheduler to fight bufferbloat
+ net.core.default_qdisc = fq_codel
+
+ [Other Info]
+
+ * Original bug report
+
+ Hi there,
+ we found a replicable issue that involves the Ubuntu Core networking and
causes complete loss of connectivity.
We run a custom board with ubuntu core: the architecure is amrhf.
We replicated this issue with an official Ubuntu Core image on a Raspberry
Pi: other platform was been tested.
It shows that it is a snap core problem which interests networkd: we use the
default network stack based on networkd + netplan.
Below steps to replicate the issue.
- 1)Setup a dhcp server for lease of about some minutes (i.e 10 minutes).
- 2)Boot the board and wait for get an ip from dhcp server
- 3)Before the lease expires, set a reservation for a different ip address
+ 1)Setup a dhcp server for lease of about some minutes (i.e 10 minutes).
+ 2)Boot the board and wait for get an ip from dhcp server
+ 3)Before the lease expires, set a reservation for a different ip address
Depending on lease duration before the lease expires( for 10 minute we have 2
minutes before ), networkd configure the new address in addition to the
previous one.
When the lease expire both ip address ( the prevoius and the new one )
disappear from the interested network interface.
Depending on lease duration before the second lease expires ( for 10 minure
we have 2 minutes before ) networkd configure only the new ip address on the
network interface and the ping toward an outside host work properly.
During the test the dhcp server records correctly leases and their
duration.
We check directly from console the network interface setting with the
tool ip, checking continuously the value for ip address and valid_lft
fields for the interested network interface.
Please note that if the ip address setting are the same between leases
the problem doesn’t jump out.
Please note that if the ip address setting are different between lease
the problem jumps out and it is very bad:
Typically the lease time on consumer router are about some day, then a
board that change ip between lease loses the network connectivity for
some day without a direct action.
Please, after a confirmation from your side of the issue, could you fix
the problem or escalate the issue at the upstream project?
We are available for further testing.
Below syslog annotated with ip address state:
-
Oct 4 09:48:06 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:49:36 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:49:25 localhost systemd-timesyncd[996]: Network configuration
changed, trying to establish connection.
Oct 4 09:49:26 localhost systemd-timesyncd[996]: Synchronized to time server
91.189.89.199:123 (ntp.ubuntu.com).
Oct 4 09:49:26 localhost systemd[1]: Starting Update resolvconf for networkd
DNS...
Oct 4 09:49:26 localhost systemd[1]: Started Update resolvconf for networkd
DNS.
Oct 4 09:49:37 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:51:07 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:51:09 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:52:39 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:52:40 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:54:10 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:54:11 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:55:41 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:54:23 localhost systemd-timesyncd[996]: Network configuration
changed, trying to establish connection.
Oct 4 09:54:23 localhost systemd[1]: Starting Update resolvconf for networkd
DNS...
Oct 4 09:54:23 localhost systemd-timesyncd[996]: Synchronized to time server
91.189.89.199:123 (ntp.ubuntu.com).
Oct 4 09:54:23 localhost systemd[1]: Started Update resolvconf for networkd
DNS.
Oct 4 09:55:43 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:57:13 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:57:14 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 09:58:44 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 09:58:46 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:00:16 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:00:17 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:01:47 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:01:48 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:03:18 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:03:05 localhost systemd-networkd[623]: eth0: DHCPv4 address
192.168.5.124/24 via 192.168.5.1 -----> here begin two ip address state
Oct 4 10:03:05 localhost systemd-timesyncd[996]: Network configuration
changed, trying to establish connection.
Oct 4 10:03:05 localhost systemd[1]: Starting Update resolvconf for networkd
DNS...
Oct 4 10:03:05 localhost systemd[1]: Started Update resolvconf for networkd
DNS.
Oct 4 10:03:15 localhost systemd-timesyncd[996]: Timed out waiting for reply
from 91.189.89.199:123 (ntp.ubuntu.com).
Oct 4 10:03:16 localhost systemd-timesyncd[996]: Synchronized to time server
91.189.89.198:123 (ntp.ubuntu.com).
Oct 4 10:03:20 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:04:50 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:04:23 localhost systemd-timesyncd[996]: Network configuration
changed, trying to establish connection. ----> disappear any address
Oct 4 10:04:23 localhost systemd[1]: Starting Update resolvconf for networkd
DNS...
Oct 4 10:04:23 localhost systemd[1]: Started Update resolvconf for networkd
DNS.
Oct 4 10:04:51 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:06:21 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:06:23 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:07:53 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:07:54 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:09:24 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:09:24 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:10:54 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
- Oct 4 10:10:55 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4
+ Oct 4 10:10:55 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4
10:12:25 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ] ------>
before this line interface eth0 don't have address, after this line the
interfaces get 192.168.5.124/24( the second lise adddress)
-
Oct 4 10:11:49 localhost systemd[1]: Starting Update resolvconf for networkd
DNS...
Oct 4 10:11:49 localhost systemd[1]: Started Update resolvconf for networkd
DNS.
Oct 4 10:12:25 localhost rsyslogd-2007: action 'action 11' suspended, next
retry is Wed Oct 4 10:13:55 2017 [v8.16.0 try http://www.rsyslog.com/e/2007 ]
Oct 4 10:13:18 localhost systemd[1]: Started Session 23 of user domotz.
-
Cheers,
Nicolino
** Changed in: systemd (Ubuntu Artful)
Status: New => In Progress
** Changed in: systemd (Ubuntu Artful)
Importance: Undecided => High
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https://bugs.launchpad.net/bugs/1721223
Title:
Networkd fail to set ip address between leases if ip address changes
on UbuntuCore
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