PPPoSSH provides an L3 tunnel over SSH and specifically Dropbear. It is easy to configure and takes little extra space to set up. Although it can be quite handy for personal use, but generally not considered for production due to the TCP-over-TCP drawbacks.

PPPoSSH generally relies on public-key cryptography. It requires to generate a private and public key for each peer and exchange only the public keys. While the private key is best never disclosed outside the peer where it was generated.