Understanding IDS for Linux
A port scan to a service like portmap (port 111), which is known to have various exploits, would be alerted by PortSentry:
Dec 9 03:03:17 flamengo portsentry: attackalert: TCP SYN/Normal scan from host: 220.127.116.11/18.104.22.168 to TCP port: 111
Learning how to interpret log files is one of the most important things that an intrusion or security analyst must learn in order to decide what action to take in a given situation. The excerpt from the PortSentry alert above was obtained from the syslog file. This alert states that on December 9 at 03:03, the host called flamengo, which has PortSentry installed, detected an SYN-flag Normal port scan in the TCP port 111 which, in general, runs the service portmap, from host IP 22.214.171.124.
A firewall is a primary security element in a network, but it will not detect attacks on a service that is already opened, such as an attack to your DNS or web server. An IDS by itself will not solve all your problems as a security element, but if you customize it for your needs, it certainly will help alert you to strange behaviors and unauthorized attempts to your host or network. With this information, you should contact the administrator of the network in which the intrusion's IP is located and then inform them of what is going on. Being in contact with the security community is also the best way to keep up to date on new attacks and the signatures to detect them. Be aware—install an IDS!
Pedro Bueno (firstname.lastname@example.org) is a former data engineer from Lucent Technologies and currently is a security engineer at Open Communications Security. He also contributes at Best Linux as a volunteer, and his favorite hobby, besides soccer, is analyzing the alerts generated by Snort.
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- Petros Koutoupis' RapidDisk
- ServersCheck's Thermal Imaging Camera Sensor
- The Italian Army Switches to LibreOffice
- Linux Mint 18
- Oracle vs. Google: Round 2
- The FBI and the Mozilla Foundation Lock Horns over Known Security Hole
- Privacy and the New Math
- Varnish Software's Varnish Massive Storage Engine
Until recently, IBM’s Power Platform was looked upon as being the system that hosted IBM’s flavor of UNIX and proprietary operating system called IBM i. These servers often are found in medium-size businesses running ERP, CRM and financials for on-premise customers. By enabling the Power platform to run the Linux OS, IBM now has positioned Power to be the platform of choice for those already running Linux that are facing scalability issues, especially customers looking at analytics, big data or cloud computing.
￼Running Linux on IBM’s Power hardware offers some obvious benefits, including improved processing speed and memory bandwidth, inherent security, and simpler deployment and management. But if you look beyond the impressive architecture, you’ll also find an open ecosystem that has given rise to a strong, innovative community, as well as an inventory of system and network management applications that really help leverage the benefits offered by running Linux on Power.Get the Guide