CODEWITHSUNDEEP
opensslsocat
Benjamin Lindqvist
Benjamin Lindqvist

Reputation: 4610

Using socat and openssl as DTLS/PSK tunnel

I want to combine openssl and socat to add encryption to plain-text UDP sockets. Specifically,

My app opens an UDP socket and sends plain-text data to 127.0.0.1:8032. I want socat to establish a DTLS session with a remote openssl server and encrypt the plain-text data sent by me app, as well as decrypt and relay back the response.

I've managed to handshake using openssl s_client:

openssl s_client -dtls1_2 -psk <KEY> -psk_identity <ID> -connect <IP>:<PORT>

but I can't get the socat tunnel to work:

socat -x -vvvvvvv SYSTEM:'openssl s_client -dtls1_2 -psk <KEY> -psk_identity <ID> -connect <IP>:<PORT>' UDP-LISTEN:8032

It seems that socat relays the plain-text data, but

I'm not sure the handshake ever gets done, and I'm not sure socat will relay the response correctly anyway with this setup. Help?

Upvotes: 2

Views: 1363

Answers (1)

Benjamin Lindqvist
Benjamin Lindqvist

Reputation: 4610

I managed to get it work with the following modification. Instead of -connect <IP>:<PORT>, use -connect <IP> -port <PORT>. Not particularily intuitive imo, but dumping the traffic with wireshark made it fairly easy to figure out. Yay wireshark.

Upvotes: 2

Related Questions