hi there
i have a question in mind
how can do something like dst-nat for ping(icmp) an specific device inside local network
And this approach makes a lot of sense, because a response to a ping tells you nothing more than that the network stack of the machine is running, but nothing about the health of the application - and what you are actually interested in is usually the availability of the service provided by the application.if any of the hosts have open ports (a web, ftp, or mail server for example), you can send tcp pickets to those ports and get a response. Most monitoring services can check for all sorts of ports.
Correct. For some things, a ping is all you need, for some things more detail is useful. I use a commercial monitoring service called UpTimeRobot.com that can ping, make a tcp probe on either any of the commonly used ports, or custom ports. There are some things that I do just ping, because all I really need to know is that a domain name resolved, but I also have it looking for an http response on a bunch of different ports (many of them are a login prompt for something), port 25 for a mail server, etc.And this approach makes a lot of sense, because a response to a ping tells you nothing more than that the network stack of the machine is running, but nothing about the health of the application - and what you are actually interested in is usually the availability of the service provided by the application.if any of the hosts have open ports (a web, ftp, or mail server for example), you can send tcp pickets to those ports and get a response. Most monitoring services can check for all sorts of ports.