I've closed down on the root cause being the /usr/lib/NetworkManager/nm-
dhcp-helper tool. Occasionally, this binary runs, but fails to correctly
send the update to NetworkManager. No errors occur when this happens;
NetworkManager in debug mode just says "accepted connection on private
socket" then "closed connection on private socket" without any updates
happening.
I've managed to work around the issue by wrapping
/usr/lib/NetworkManager/nm-dhcp-helper in a shell script that simply
performs the same lease update until the logs indicate that
NetworkManager received it. This doesn't fix the communication problem,
but adds a safety net that prevents the resulting issues. It's been
tested in an office network of some 12 PCs.
If anyone runs into this issue as well, run the following script to work
around it:
-----8<-----
#!/bin/bash
HELPERSCRIPT="/usr/lib/NetworkManager/nm-dhcp-helper"
HELPERBIN="/usr/lib/NetworkManager/nm-dhcp-helper.bin"
function is_elf() {
readelf -h "$1" >/dev/null 2>&1
if [ "$?" = "1" ]; then
echo "0"
else
echo "1"
fi
}
if [ "$(is_elf $HELPERSCRIPT)" = "1" ]; then
mv "$HELPERSCRIPT" "$HELPERBIN"
fi
cat <<EOF >"$HELPERSCRIPT"
#!/usr/bin/perl
use strict;
use warnings;
if(\$< != 0) {
die "Must run as root\n";
}
my \$reason = \$ENV{reason} || "";
if(\$reason eq "PREINIT") {
# not lease information, so waiting for the journal will make
# nm-dhcp-helper wait for too long, just send it once and exit so
# dhclient will start to get a lease
system("${HELPERBIN}");
exit(0);
}
my \$attempts = 0;
my \$success = 0;
while(\$attempts < 10) {
\$attempts++;
my \$time = time();
sleep(1);
system("${HELPERBIN}");
sleep(1);
my \$leasetime = \`/bin/journalctl --since='\\@\$time' | grep
NetworkManager | grep ' lease time ' | wc -l\`;
if(\$leasetime == 1) {
\$success = 1;
last;
}
# Try again in 5 seconds
sleep(5);
}
if(\$attempts > 1) {
open my \$fh, ">>", "/tmp/nm-helper-retries.log" or die \$!;
my \$date = \`/bin/date\`;
1 while chomp \$date;
if(\$success) {
print \$fh "\$date: needed \$attempts attempts to update
NetworkManager (\$reason).\n";
} else {
print \$fh "\$date: gave up after \$attempts attempts
(\$reason).\n";
}
close \$fh;
}
exit(0);
EOF
chmod +x $HELPERSCRIPT
/usr/sbin/aa-complain /etc/apparmor.d/sbin.dhclient
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1696415
Title:
NetworkManager does not update IPv4 address lifetime even though DHCP
lease was successfully renewed
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1696415/+subscriptions
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