[veganjay]

I have burned a lot of time thinking a host was down only to find it blocks ICMP echo (ping).

As a follow-up to a ping fail, I check to see if a known port is open using nmap.

gist: https://gist.github.com/veganjay/6b902c478bda429187f39e53a5b...

[redrove]

I find that a little hard to remember, and nmap isn't as widely available as netcat:

  nc -zv 1.1.1.1 443

Alternatively, the most barebones version, useful for inside a container where all you have is a shell and the kernel:

  cat > /dev/tcp/www.google.com/443

[tredre3]

> Alternatively, the most barebones version, useful for inside a container where all you have is a shell and the kernel:

> cat > /dev/tcp/www.google.com/443

I was unfamiliar with this device so I googled a bit. This isn't a real file/device, it's a bash-ism when built with --enable-net-redirections (apparently disabled in debian-based distros [1]).

That's too bad, would have been cool to have such easy access to sockets anywhere using fopen().

1. https://www.oreilly.com/library/view/bash-cookbook/059652678...

[jonas-w]

If it is a device in your local network, arp-scanning is also very useful. IIRC e.g. windows or ios devices won't respond to icmp pings but to arp "pings".