Communication via public and internal networks by means of insecure protocols constitutes a potential threat. If, for example, outdated versions of IPSec, SSH, or SSL/TLS are used to establish a tunnel between two networks or endpoints, it cannot be guaranteed that this tunnel is sufficiently secure and the information transmitted in it is adequately protected. Attackers may exploit vulnerabilities of these protocols in order to inject their own contents into protected connections. Protocols in which information is transmitted in plain text are generally considered insecure.