NTPD service is deleting and enabling the network
We have a couple of virtual interfaces configured on eth0 on a CentOS, and every now and then, they went down seemingly out of the blue. Now after going through the log files, I found out that apparently ntpd deletes all eth0 interfaces, and that dhclient automatically brings eth0 back up. The virtual interfaces, however, stay down which causes several of our websites to be inaccessible.
Can someone explain to me why ntpd deletes interfaces? Can / should that be turned off, or can / should I configure dhclient to bring the virtual interfaces back up automatically, too?
EDIT// The log files that I should've posted :
Nov 12 13:10:28 raptor dhclient[20048]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x6a825e97)
Nov 12 13:10:42 raptor dhclient[20048]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8 (xid=0x24554092)
Nov 12 13:10:42 raptor dhclient[20048]: DHCPOFFER from 96.126.108.78
Nov 12 13:10:42 raptor dhclient[20048]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x24554092)
Nov 12 13:10:42 raptor dhclient[20048]: DHCPACK from 96.126.108.78 (xid=0x24554092)
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #31 eth0, 50.116.50.97#123, interface stats: received=3255, sent=3256, dropped=0, active_time=1559394 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #32 eth0:0, 50.116.53.56#123, interface stats: received=3, sent=0, dropped=0, active_time=1559391 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #33 eth0:1, 66.175.211.192#123, interface stats: received=2, sent=0, dropped=0, active_time=1559389 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #34 eth0:2, 50.116.53.95#123, interface stats: received=3, sent=0, dropped=0, active_time=1559387 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #35 eth0:3, 97.107.132.32#123, interface stats: received=2, sent=0, dropped=0, active_time=1559385 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #36 eth0:4, 50.116.56.201#123, interface stats: received=2, sent=0, dropped=0, active_time=1559383 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #37 eth0:5, 66.175.212.121#123, interface stats: received=2, sent=0, dropped=0, active_time=1559381 secs
Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #38 eth0:6, 66.175.215.137#123, interface stats: received=2, sent=0, dropped=0, active_time=1559379 secs
Nov 12 13:10:44 raptor NET[1573]: /sbin/dhclient-script : updated /etc/resolv.conf
Nov 12 13:10:44 raptor dhclient[20048]: bound to 50.116.50.97 -- renewal in 32692 seconds.
Nov 12 13:10:45 raptor ntpd[2109]: Listening on interface #39 eth0, 50.116.50.97#123 Enabled
The eth0 config :
DEVICE="eth0"
ONBOOT="yes"
BOOTPROTO="dhcp"
IPV6INIT="no"
IPADDR=50.116.50.97
NETMASK=255.255.255.0
GATEWAY=50.116.50.1
And the virtual interfaces (I posted the first one only, they look the same for the most part) :
# Configuration for eth0:0
DEVICE=eth0:0
BOOTPROTO=none
# This line ensures that the interface will be brought up during boot.
ONBOOT=yes
# eth0:0
IPADDR=50.116.53.56
NETMASK=255.255.255.0
Answers答复：
The BOOTPROTO="dhcp" means you have DHCP.
If you look, the DHCP client is running immediately before ntp changes anything. I think your DHCP client is removing all the static addresses on eth0. When NTP notices this it knows that it needs to stop listening on all the sockets it was listening on for the static addresses.
Resolution
Use the -L option to tell ntpd to not listen on virtual interfaces. You can set -L in /etc/sysconfig/ntpd.
When the interface is down or removed, ntpd updates the listen interface according to the current interface status.
--- /etc/sysconfig/ntpd.bak 2016-09-26 08:35:05.408966980 -0400
+++ /etc/sysconfig/ntpd 2016-09-26 08:35:14.461086105 -0400
@@ -1,2 +1,2 @@
# Command line options for ntpd
-OPTIONS="-g"
+OPTIONS="-g -L"
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