Add DTLS (TLS over UDP) support

[OrenShm]

What OS?

• [x] Windows
• [ ] Mac
• [ ] Linux (Which distro?)

Description of issue

Currently the packet sender supports udp \ tcp \ ssl (TLS). It would be great if it could also support DTLS (Datagram TLS == "TLS over UDP").

It could be checked again OpenSSL \ mbedTLS.

Opening DTLS server using mbedTLS: ./programs/ssl/ssl_server2 ca_file= crt_file= key_file= server_addr= server_port= auth_mode=required dtls=1

Opening DTLS server using OpenSSL: openssl s_server -accept -auth -cert -key -cert2 -key2 -CAfile -servername -Verify required -dtls1_2

An echo server of DTLS could be found here (It also requires openssl)- https://github.com/nplab/DTLS-Examples

[dannagle]

Very interesting idea. A few years back when I looked at this, I determined DTLS was not that stable with hard-to-find examples. It seems worth another look now.

[OrenShm]

Sounds great, thanks 👍

[danfoxley]

For a WebRTC application, the large DTLS (larger than MTU size) packet gets fragmented and reassembled. We've run into scenarios where firewalls are blocking large UPD.