We're very impressed by the collective smarts of the security community and we highly recommend reading the whole list and investigating any tools you are unfamiliar with. Click any tool name for more details on that particular application, including the chance to read (and write) reviews. Many site elements are explained by tool tips if you hover your mouse over them. Enjoy!
Ettercap is a suite for man in the middle attacks on LAN. It features sniffing of live connections, content filtering on the fly and many other interesting tricks.
It supports active and passive dissection of many protocols (even ciphered ones) and includes many feature for network and host analysis.
Read 7 reviews.
Latest release: version 0.8.0-Lacassagne on Sept. 21, 2013 (1 year, 5 months ago).
Ntop shows network usage in a way similar to what top does for processes. In interactive mode, it displays the network status on the user's terminal. In Web mode, it acts as a Web server, creating an HTML dump of the network status. It sports a NetFlow/sFlow emitter/collector, an HTTP-based client interface for creating ntop-centric monitoring applications, and RRD for persistently storing traffic statistics.
Read 2 reviews.
Latest release: version 4.0.3 on Oct. 24, 2010 (4 years, 4 months ago).
SolarWinds has created and sells dozens of special-purpose tools targeted at systems administrators. Security-related tools include many network discovery scanners, an SNMP brute-force cracker, router password decryption, a TCP connection reset program, one of the fastest and easiest router config download/upload applications available and more.
Read 1 review.
ngrep strives to provide most of GNU grep's common features, applying them to the network layer. ngrep is a pcap-aware tool that will allow you to specify extended regular or hexadecimal expressions to match against data payloads of packets. It currently recognizes TCP, UDP and ICMP across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces, and understands bpf filter logic in the same fashion as more common packet sniffing tools, such as tcpdump and snoop.
Review this tool.
Latest release: version 1.45 on Nov. 28, 2006 (8 years, 3 months ago).
Featuring link layer, IP, and TCP modes, EtherApe displays network activity graphically with a color coded protocols display. Hosts and links change in size with traffic. It supports Ethernet, WLAN, FDDI, Token Ring, ISDN, PPP and SLIP devices. It can filter traffic to be shown, and can read traffic from a file as well as live from the network.
Read 3 reviews.
Latest release: version 0.9.13 on May 5, 2013 (1 year, 9 months ago).
Splunk is a tool to search, report, monitor and analyze real-time streaming and historical IT data. It collects logs from a variety of sources and makes them searchable in a unified interface.
Read 5 reviews.
Latest release: version 4.1.7 on Feb. 14, 2011 (4 years ago).
NetWitness NextGen is a network security monitor. The heart of the monitor is the Decoder subsystem that records network traffic for analysis. The Investigator is a protocol analyzer meant to be run on captured traffic.
Read 2 reviews.
Latest release: version 22.214.171.124 on March 17, 2010 (4 years, 11 months ago).
Nagios is a system and network monitoring application. It watches hosts and services that you specify, alerting you when things go bad and when they get better. Some of its many features include monitoring of network services (SMTP, POP3, HTTP, NNTP, ICMP, etc.), monitoring of host resources (processor load, disk usage, etc.), and contact notifications when service or host problems occur and get resolved (via email, pager, or user-defined method).
Read 6 reviews.
Latest release: version 4.0.6 on April 29, 2014 (10 months ago).
Argus is a fixed-model Real Time Flow Monitor designed to track and report on the status and performance of all network transactions seen in a data network traffic stream. Argus provides a common data format for reporting flow metrics such as connectivity, capacity, demand, loss, delay, and jitter on a per transaction basis. The record format that Argus uses is flexible and extensible, supporting generic flow identifiers and metrics, as well as application/protocol specific information.
There is also another open source network monitoring program named Argus.
Read 1 review.
Latest release: version 3.7 on Feb. 1, 2013 (2 years ago).
P0f is able to identify the operating system of a target host simply by examining captured packets even when the device in question is behind an overzealous packet firewall. P0f does not generate ANY additional network traffic, direct or indirect. No name lookups, no mysterious probes, no ARIN queries, nothing. In the hands of advanced users, P0f can detect firewall presence, NAT use, existence of load balancers, and more!
Review this tool.
Latest release: version 2.0.8 on Sept. 6, 2006 (8 years, 5 months ago).