Linux
banshee/linux-collection/linux/snmp/
clock
Offset of a Linux host's clock from a time server, read by SNMP and compared by NTP.
by banshee1 installation2 versions
v2Latest
Published on October 28, 2026. One naming convention across collections; documentation completed.
Clock of a Linux host, by SNMP
Returns the offset of the host's clock from a time server, with and without its sign, in seconds. One watch is offered: the clock off.
Versions
Generic: net-snmp serves hrSystemDate with its offset from UTC on any Linux; an agent that leaves the offset out stops the collector (see below).
How it works
The collector reads the system time, hrSystemDate (HOST-RESOURCES-MIB), by SNMP, and asks a time server for its time by NTP (pool.ntp.org when the "Time server" variable is unset).
- The server's time is brought back to the middle of the SNMP read: neither the SNMP round trip, nor the time between the two reads, nor the error of the poller's own clock counts in the offset.
- A positive offset means the host's clock is ahead; negative, behind.
- An agent that serves the date without its offset from UTC does not say which instant it is: the collector then stops as misconfigured rather than guess. net-snmp serves the offset.
- A time server that does not answer stops the collector as unreachable.
Prerequisites
snmpd(net-snmp) running on the host, listening on an address the poller reaches (UDP 161), with the firewall open to the poller only.- The view granted to the poller includes
hrSystem(.1.3.6.1.2.1.25.1), which most default configurations already allow. - Read-only access, SNMPv2c or SNMPv3, set on the host or one of its folders (
protocol:snmp:*variables). - The poller reaches the time server on UDP 123 (
protocol:ntp:server,protocol:ntp:timeout).
# /etc/snmp/snmpd.conf
agentaddress udp:161
view banshee included .1.3.6.1.2.1.25.1
rocommunity <community> 192.0.2.10 -V banshee
# or: rouser <user> priv -V bansheeOutputs
| Name | Label | Unit | Per instance |
|---|---|---|---|
offset | Offset from the time server | s | no |
drift | Offset, without its sign | s | no |
Watches
| Name | Title | Kind | Defaults | Checked by default |
|---|---|---|---|---|
clock-drift | Clock off | above a threshold, on drift | warning above 5 s, critical above 60 s | yes |
Limits
hrSystemDateis only precise to a tenth of a second: an offset below that is noise.- The collector measures the offset; it does not say whether the host synchronises its clock (chrony, systemd-timesyncd).