Also the number of users will be limited toby the number of lines available. Some users will have to pay long-distance charges is they do not live in he local area. One time password systems offer a good defence against password attacks for both modem and Internet. Network access is commonly a more favorable remote access solution because it is cost effective and convenient for employee to use. One-time passwords and firewalls do not protect against connection hijacking.
Hijacking allows commands can be transparently added to remote terminal sessions.
The necessary programs can be bought off the shelf and a competent programmer could write them in a matter of days. The best defence against these attacks is encryption. By encrypting the login data stream it becomes impossible for attackers to monitor the communications as well as hijack the data stream. Other advantages of the use of encryption is the ability of the hosts authenticate with the use of public keys in addition to the passwords, thus further increasing the security. Systems can be configured to only allow inbound access from known sites and ignore login attempts from unknown Internet sites.