A simple command line tool for displaying information about a TLS connection. The tool is largely based on this Stack Overflow answer.
Run dotnet build from the command line. This will build executables for .NET Framework and .NET Core.
Run tls-info <host name> [<host name 2> ... <host name N>]. For each host name provided, the tool will attempt to create a connection using a TcpClient and an SslStream, and then display information about the selected cipher suite and the remote server certificate. Where no port is specified in the host name, port 443 will be used.
Display information for Google and LinkedIn:
tls-info www.google.com www.linkedin.com
Display information for localhost on a specific port:
tls-info localhost:43889
Display information for specific IPv4 and v6 addresses:
tls-info 2002:0a00:0001::0a00:0001:44321 10.0.0.1:44321
Example output:
=============================== localhost:48189 ===============================
Resolved Host Name: localhost
TLS Version: Tls12
Key Exchange Algorithm: Ecdhe
Cipher Algorithm: Aes256
Hash Algorithm: Sha384
Certificate:
[Subject]
CN=localhost
[Issuer]
CN=localhost
[Serial Number]
0123456789ABCDEF01
[Not Before]
01/01/2020 13:48:42
[Not After]
01/01/2021 13:48:42
[Thumbprint]
FEDCBA9876543210FEDCBA9876543210FEDCBA98