46 CONTENTS
14.3 Action on local network failures
AutoPing is designed to control operation of remote hosts. You usually don't want to e.g. cycle power to all servers
if you turn on same subnet restriction. So AutoPing tries not to trigger if there might be a problem local to the unit
itself. For example, if you detach the Ethernet cable from the unit, you'll see messages similar to the following:
kernel: eth0: link down
config.net: Interface "eth0" is down
autoping: ping x.y.z.t: no usable route to host, ..., not considered a failure
and no actions will be performed. A similar situation will occur if you reconfigure the controller to use a new IP
network from which old addresses are unreachable.
14.4 Advanced ping targets
AutoPing targets don't have to be IP addresses. If you enter a hostname, it will be resolved before sending each
request. If the name resolution fails, it is assumed to be a local error and, as described above, no action is taken. If
a name is resolved to multiple IP addresses, a random one is chosen.
AutoPing defaults to checking targets using the ICMP protocol by default. A variety of other ping target kinds can
be used if you specify a URL instead of simply an IP address or hostname. Supported URL schemes include:
• icmp — this is explicit specification of the "regular" ping protocol, e.g. icmp://192.168.0.1 is equiva-
lent to 192.168.0.1 (note that no trailing slash is used);
• tcp — this causes AutoPing to try to establish a TCP connection to the given port, e.g. tcp←-
://192.168.0.1:22 can be used to check that there's a service listening on TCP port 22 (usually SSH)
of 192.168.0.1 (note that no trailing slash is used);
• http and https — this causes AutoPing to perform a HTTP/HTTPS GET request for the given URL, e.g.
http://www.digital-loggers.com/index.html can be used to check that the web server is
responding and can serve its main page.
14.5 AutoPing events
The most often encountered AutoPing events are:
• pinging ... (timeout)
• ping ... succeeded (time)
• ping ... failed (time)
The time is request round-trip time, in seconds. Note that it's purely informative and can't be used as a measure of
target response time unless it has order of hundreds of milliseconds and above.
Several failures in a row trigger AutoPing actions which are reported with corresponding events:
• item ... (addresses...) failed [failures/max]
• item ... (addresses...) failed over (max) times in a row, disabling
DLI DIN4 User’s Guide: 20170809T111540Z
To Next Page
Loading...