Notice when WAN disconnected

[SolidPaint]

For any device in the LAN which is past the Modem (i.e. PC, Smartphone, Router etc.):

Is it possible to check if WAN disconnected?



The naive approach is to simply ping to a "known" address, though it doesn't sound robust.

 

[degrub]

the router does it automatically.
windows and mac OS do so as well and display the "no internet" symbol.
Ping is very reliable and can be automated - pingplotter for example.
Nothing naive about it..

 

[SolidPaint]

the router does it automatically.
windows and mac OS do so as well and display the "no internet" symbol.
Ping is very reliable and can be automated - pingplotter for example.
Nothing naive about it..

Then how do you choose a reliable server to ping to?
How do you know that packet won't be dropped somehow? A glitch or something

 

[degrub]

pingplotter can indicate drops/glitches, phase of the moon, etc. for the packets.
Google is generally pretty reliable at 8.8.8.8

 

[drinkingbird]

For any device in the LAN which is past the Modem (i.e. PC, Smartphone, Router etc.):

Is it possible to check if WAN disconnected?



The naive approach is to simply ping to a "known" address, though it doesn't sound robust.

As already mentioned, if you just want your web browser to tell you, the asus is configured to do this automatically by default. You'll get a page saying WAN is down. However it requires a physical link down by default. You can change this under administration - system and enable ping or dns lookup for network monitoring so even if the physical link is up it will detect a "soft" failure.

However most OSes will detect the outage themselves and the asus redirect won't work as they will give their own message that the internet is down before even attempting to go out to the internet, so that feature has been somewhat obsoleted by most OSes.

If you want to monitor from a PC, pingplotter to 8.8.8.8 or google.com will work. Even if it drops a packet every now and then that will be easily distinguished from a real outage of many dropped pings.

 

[SolidPaint]

pingplotter can indicate drops/glitches, phase of the moon, etc. for the packets.
Google is generally pretty reliable at 8.8.8.8

As already mentioned, if you just want your web browser to tell you, the asus is configured to do this automatically by default. You'll get a page saying WAN is down. However it requires a physical link down by default. You can change this under administration - system and enable ping or dns lookup for network monitoring so even if the physical link is up it will detect a "soft" failure.

However most OSes will detect the outage themselves and the asus redirect won't work as they will give their own message that the internet is down before even attempting to go out to the internet, so that feature has been somewhat obsoleted by most OSes.

If you want to monitor from a PC, pingplotter to 8.8.8.8 or google.com will work. Even if it drops a packet every now and then that will be easily distinguished from a real outage of many dropped pings.

Thank you guys for the reply.

So anyone who wants to test for WAN connectivity is constantly pinging google's server 8.8.8.8 ?
Isn't that overloading their servers or something?
Sounds like DDOS that everyone agreed to(?)

 

[ColinTaylor]

So anyone who wants to test for WAN connectivity is constantly pinging google's server 8.8.8.8 ?
Isn't that overloading their servers or something?
Sounds like DDOS that everyone agreed to(?)

No. ICMP (ping) traffic is a normal part of how the internet works. Sending a ping to a server once a second (or once every 5 seconds in the case of router) is negligible in the scheme of things. For a DoS attack you'd have to be sending hundreds of thousands of pings per second.

 

[drinkingbird]

Thank you guys for the reply.

So anyone who wants to test for WAN connectivity is constantly pinging google's server 8.8.8.8 ?
Isn't that overloading their servers or something?
Sounds like DDOS that everyone agreed to(?)

As @ColinTaylor mentioned, it is normal and they're "used to it". 8.8.8.8 isn't a single machine, it is dozens if not hundreds spread throughout the country (my guess would be international as well). And they have firewalls that rate limit pings and dns lookups to prevent against DOS/DDOS attacks anyway. If google was concerned, they would just block ping alltogether.

It is virtually impossible to DDOS using ping these days, everything is designed to give it lowest priority and drop it if it is excessive. DDOS against DNS would be doing millions of DNS lookups simultaneously from thousands of machines.