Lesson 10 – SECURING YOUR NETWORK

Security devices Internal security External security Viruses and other malicious software OVERVIEW

Firewall: System enforcing security policy between two Networks. SECURITY DEVICES

Proxy Server: Server acting as a proxy (an anonymous intermediary) for Network users. Security devices

Packet filter: Enables users to set criteria for allowed and disallowed packets. Security devices

Securing Network from internal threats like: Accessing information inappropriately. Accessing other users’ files. Impersonating other users. Performing criminal activities on systems. Packet “sniffing” on the Network. INTERNAL SECURITY

Account security File and directory permissions Practices and user education Internal security

Process of managing the user accounts enabled on the Network. Account security

To manage security: Remove the guest account. Rename the default name for the administrative account. Remove access to Network resources. Work closely with HR/legal departments. Review newly assigned permissions. Account security

To maintain password security: Get users to change their Network password regularly. Set the reuse policy. Have passwords that are at least eight characters long. Establish thresholds. Account security

Control access to files and directories by using built-in permissions. File and directory permissions

Generic directory roles: Create only Read only Change Full control File and directory permissions

Inform users what is expected of them in terms of security. Discuss security issues with new employees. Have users acknowledge their understanding. Periodically audit users’ security actions. Review the NOS’ security logs. Practice and user education

Process of securing the Network from external threats. EXTERNAL SECURITY

Types of threats: Front-door threats Back-door threats Denial of service External security

Arise when a user from outside the company finds a user password and logs on to the Network. Front-door threats

Solutions: Separate Network resources accessed from and outside the LAN. Control users accessing LAN from outside the LAN. Set up a separate remote access account for remote users. Set up user accounts to use dial-back. Change password when employee with broad access resigns. Front-door threats

Software or hardware bugs in the Network’s OS enabling an outsider to crack the Network’s security. Back-door threats

Solutions: Host the company’s web site on an external server. Implement a firewall router. Review security settings for the web server. Place web server for non-employees outside the firewall.

Attacks that deny service to the Network. Denial of service

Solutions: Keep various Network software “current”. Disallow Internet Control Message Protocol (ICMP) traffic service.

Denial of service Demilitarized Zone (DMZ): The area between computers placed between the firewall an connection to an external Network.

VIRUSES AND OTHER MALICIOUS SOFTWARE

Program that spreads by infecting other files with a copy of itself. Files infected by viruses include program files (.COM,.EXE, and.DLL). Virus

Program that propagates by sending copies of itself to other computers. Spreads by attaching to s along with a message. Worm

Program that claims to do something interesting and performs malicious actions in the background. Trojan horse

Malicious piece of programming code inserted into a normal program. Can be timed to erase key files. Logic bomb

Internal security: Account security Account password security File and directory permissions SUMMARY

External security: Front-door threats Back-door threats Denial of service Summary

Viruses and other malicious software: Viruses Worms Trojan horses Logic bombs Summary