To reproduce the issue:
Server session
$ coap-server -v9 -n -k secretPSK -c server.pem -C ca.pem -R /etc/ssl/certs
Client session
$ examples/coap-client -v9 coaps://127.0.0.1/
include/coap2/coap_dtls.h:
src/coap_gnutls.c:
If neither coap_new_client_session_pki() or coap_new_client_session_psk()
is called, but coap_new_client_session() is (as done by coap-client if
no PKI or PSK options set), then set up a default PKI session to be
able to talk to a coap server.
Jon Shallow
b74aab1971