Wardialing is a method used to attempt to gain access to a computer or computer network by using a phone line to connect to a remote computer modem. When war dialing, a range of computer numbers may be dialed and if a modem is detected on the other end, the attacker may attempt to identify the operating system that is installed on the remote computer. If the remote computer operating system can be identified, the attacker may attempt a penetration test to gain access to the computer. When wardialing common user names and passwords such as default user names and passwords may be used to attempt to access the network or computer systems. Wardialing attacks may try to exploit a vulnerability in the computer system to gain access but will usually try to use common or default user names and passwords to gain access.