How to check particular service/ports is avaliable on device.
Common ports like ftp, http, https, telnet, etc..
Error: Failed to connect to the remote host.
We can check this by telnet particular service with its port no. For example if I am unable to ftp (ftp port 21) on a server/router(remote device ip add 188.8.131.52), I will check
> telnet 184.108.40.206 21
>telnet 220.127.116.11 161
>telnet 18.104.22.168 162
If telnet will successful, it will shows that particular service or port is open on that device/server, if not it will show you error.
>telnet 22.214.171.124 80
>telnet 126.96.36.199 443
Several times we faced problems in network while upgradation, transfer data, access remote devices, etc because customer might have blocked particular service(s) on device.