Fast, lightweight CLI tool to check if a host supports HTTP/2 via ALPN.
Tested with OpenSSL 1.1.1d.
On Debian-based:
sudo apt install libssl-dev
Use make. To skip certificate verification, compile with make noverify.
./ish2 host [port].
By default, port 443 is used.
For example:
$ ./ish2 www.google.com
www.google.com h2
$ ./ish2 www.github.com 443
www.github.com http/1.1
NOTE: this tool hangs when the server does not support HTTPS. The quickest workaround is to use timeout(1):
$ timeout 3 ./ish2 deaddomain.com