11 ms·

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

• redrove 4y ago
  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 4y ago
    > 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/0596526784/ch15s09.html https://www.oreilly.com/library/view/bash-cookbook/059652678...
• jonas-w 4y ago
  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".