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Using nc (netcat) instead of telnet

A commonly used command in Linux is telnet, used to check if a connection can be established to another device. For example:

telnet <ip/host> <port>

However, when this fails, a decent error message is missing. The only thing the user can do is use [ Ctrl ] + [ C ] to abort the command. Instead of teltnet, it's better to use nc, which is a modern replacement and also has a built-in option for connection timeouts. Using nc is considered much cleaner/better than using telnet for connectivity checks. For example:

nc -vz -w 5 <ip/host> <port>
  • -w 5 → 5-second timeout
  • -z → just scan, don’t send data
  • -v → verbose

Examples, comparing the output from telnet to nc/netcat:

Using telnet
Using nc/netcat
telnet concera.com 80

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 nc -vz -w 5 concera.com 80

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telnet concera.com 800

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 nc -vz -w 5 concera.com 800

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telnet 192.168.200.123 443

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 nc -vz -w 5 192.168.200.123 800

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References:
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