Abstract: The growing fast of the computer networks require a very high security, to keep the networks , data and , the resources of the network as much safe as possible and to get sure safely and trusty communication between the networks members . The security issues is rising as it is facing a growing problems of unauthorized access , viruses , malicious , etc. so it demand an updated technologies to face all of these circumstance ,The growing rapidly of networks as we said coming with security risks , so every computer network should be fully secure and safe unfortunately it is something can't be possible easily . In the paper we will look to the security issues and count measures of the computer networks and going further also about the intrusion detection systems . SNORT which it’s open source system and also SURICATA and also comparison of these two tools