Network Toolbox

The commands you'd type into a Linux shell to debug connectivity: dig, curl, nc/telnet, ping, a TLS handshake and whois. They run from a server in Tokyo, so you see your DNS, web server and firewall the way the rest of the internet does.

visitor@tokyo-1: ~

Type a command below or pick an example. help lists everything.

Try these

Where does this domain's mail go?
Has a DNS change reached Cloudflare, Google and Quad9?
Redirects, headers and timings
Is the SSH port reachable from outside?
Latency from Tokyo
TLS version, cipher and certificate chain
Who owns this address?

Ground rules

One host, one port per command. No ranges, lists or scans; trying lots of different ports gets refused.
Public internet only. Private, loopback and cloud-metadata addresses are refused, after DNS and again at connect time.
Looks, never touches. curl does plain GET/HEAD with no custom headers or body; nc connects and listens, it sends nothing.
Small budgets. 10 commands a minute per visitor, and every target gets only a few probes a minute from everyone combined.
No raw sockets, so no traceroute or mtr. Port 25 is blocked by Japanese ISPs (OP25B); use 465 or 587.

Requests identify themselves as harshgulhane-nettools. Commands aren't stored; what was probed is logged briefly to spot abuse.