Network Security Management prevents unauthorized use of resources – if no secure authentication and secure authorization exists (eg rlogin). Monitoring of data and control information – all unencrypted protocols, such as POP3, IMAP, SMTP, Telnet, rlogin and http.
Smuggling of data or information – all logs without adequate message authentication, such as POP3, SMTP, Telnet, rlogin and http. Tunnels can be used to approved protocols (HTTP) embed data traffic. This firewall rules can be circumvented. A more detailed description can be found.
For example, the SSH client builds over https and proxy to connect to a server outside of the internal network. This bypassing the rules that control SSH traffic to the outside. This compound can also be reversed whereby a connection from the outside is connected to the internal network.
The congestion of services is referred to as DoS attacks (Denial of Service).
