Tools Network Admin & Sysadmin

Tools PenTest
#Nessus
#Acunetix
#Canvas  
#Open Resolver
#CentralOps  
#NetCraft

Firewall 
#Pfsense
#Fail2Ban

Port Blocking
#PortSentry

OpenSource IDS 
# OSSEC
OSSEC is an Open Source Host-based Intrusion Detection System that performs log analysis, file integrity checking, policy monitoring, rootkit detection, real-time alerting and active response. It runs on most operating systems, including Linux, MacOS, Solaris, HP-UX, AIX and Windows.

#Suricata
Suricata is truly open source. First of all, it is released under GPLv2 licence and, equally important, the copyright for the code is owned by the Open Information Security Foundation (OISF), created specifically to be a long term safe haven for Suricata. There is not an IPO or acquisition in Suricata’s future. It is open source and will remain open source, governed equally by the community and vendors who rely on and help maintain the engine. Thus Suricata is completely vendor and platform neutral.

#Snort
Snort® is an open source network intrusion prevention and detection system (IDS/IPS) developed by Sourcefire. Combining the benefits of signature, protocol, and anomaly-based inspection, Snort is the most widely deployed IDS/IPS technology worldwide. With millions of downloads and nearly 400,000 registered users, Snort has become the de facto standard for IPS.