A Stateful Packet Inspection (SPI) firewall, Login/Intrusion Detection and Security application for Linux servers.

The latest version of csf can be downloaded here: csf.tgz

The latest SHA256 checksums of all our products can be downloaded here: checksums.txt

• Straight-forward SPI iptables firewall script
• Daemon process that checks for login authentication failures for:
  • Courier imap, Dovecot, uw-imap, Kerio
  • openSSH
  •  cPanel, WHM, Webmail (cPanel servers only)
  • Pure-ftpd, vsftpd, Proftpd
  • Password protected web pages (htpasswd)
  •  Mod_security failures (v1 and v2)
  • Suhosin failures
  • Exim SMTP AUTH
  • Custom login failures with separate log file and regular expression matching
• POP3/IMAP login tracking to enforce logins per hour
• SSH login notification
• SU login notification
• Excessive connection blocking
• UI Integration for cPanel, DirectAdmin, InterWorx, CentOS Web Panel (CWP), VestaCP and Webmin
• Easy upgrade between versions from within the control panel
• Easy upgrade between versions from shell
• Pre-configured to work on a cPanel server with all the standard cPanel ports open
• Pre-configured to work on a DirectAdmin server with all the standard DirectAdmin ports open
• Auto-configures the SSH port if it’s non-standard on installation
• Block traffic on unused server IP addresses – helps reduce the risk to your server
• Alert when end-user scripts sending excessive emails per hour – for identifying spamming scripts
• Suspicious process reporting – reports potential exploits running on the server
• Excessive user processes reporting
• Excessive user process usage reporting and optional termination
• Suspicious file reporting – reports potential exploit files in /tmp and similar directories
• Directory and file watching – reports if a watched directory or a file changes
• Block traffic on a variety of Block Lists including DShield Block List and Spamhaus DROP List
• BOGON packet protection
• Pre-configured settings for Low, Medium or High firewall security (cPanel servers only)
• Works with multiple ethernet devices
• Server Security Check – Performs a basic security and settings check on the server (via cPanel/DirectAdmin/Webmin UI)
• Allow Dynamic DNS IP addresses – always allow your IP address even if it changes whenever you connect to the internet
• Alert sent if server load average remains high for a specified length of time
• mod_security log reporting (if installed)
• Email relay tracking – tracks all email sent through the server and issues alerts for excessive usage (cPanel servers only)
• IDS (Intrusion Detection System) – the last line of detection alerts you to changes to system and application binaries
• SYN Flood protection
• Ping of death protection
• Port Scan tracking and blocking
• Permanent and Temporary (with TTL) IP blocking
• Exploit checks
• Account modification tracking – sends alerts if an account entry is modified, e.g. if the password is changed or the login shell
• Shared syslog aware
• Messenger Service – Allows you to redirect connection requests from blocked IP addresses to preconfigured text and html pages to inform the visitor that they have been blocked in the firewall. This can be particularly useful for those with a large user base and help process support requests more efficiently
•  Country Code blocking – Allows you to deny or allow access by ISO Country Code
•  Port Flooding Detection – Per IP, per Port connection flooding detection and mitigation to help block DOS attacks
• WHM root access notification (cPanel servers only)
• lfd Clustering – allows IP address blocks to be automatically propagated around a group of servers running lfd. It allows allows cluster-wide allows, removals and configuration changes
• Quick start csf – deferred startup by lfd for servers with large block and/or allow lists
• Distributed Login Failure Attack detection
• Temporary IP allows (with TTL)
• IPv6 Support with ip6tables
• Integrated UI – no need for a separate Control Panel or Apache to use the csf configuration
• Integrated support for cse within the Integrated UI
• cPanel Reseller access to per reseller configurable options Unblock, Deny, Allow and Search IP address blocks
• System Statistics – Basic graphs showing the performance of the server, e.g. Load Averages, CPU Usage, Memory Usage, etc
• ipset support for large IP lists
• Integrated with the CloudFlare Firewall
• …lots more!

The reason we have developed this suite is that we have found over the years of providing server services that many of the tools available for the task are either over-complex, not user friendly, or simply aren’t as effective as they could be.

We have developed an SPI iptables firewall that is comprehensive, straight-forward, easy and flexible to configure

To complement the ConfigServer Firewall (csf), we have developed a Login Failure Daemon (lfd) process that runs all the time and periodically (every X seconds) scans the latest log file entries for login attempts against your server that continually fail within a short period of time. Such attempts are often called “Brute-force attacks” and the daemon process responds very quickly to such patterns and blocks offending IP’s quickly. Other similar products run every x minutes via cron and as such often miss break-in attempts until after they’ve finished, our daemon eliminates such long waits and makes it much more effective at performing its task.

Login tracking is an extension of lfd, it keeps track of POP3 and IMAP logins and limits them to X connections per hour per account per IP address.

To help with the ease and flexibility of the suite we have developed a front-end to both csf and lfd which is accessible by the root account through cPanel, DirectAdmin and Webmin. From there you can modify the configuration files and stop, start and restart the applications and check their status. This makes configuring and managing the firewall very simple indeed.

This application is released under our script license. It is released free of charge, with no warranty to its suitability. There is no support provided with this application except through the ConfigServer Community Forum where the community of csf users may assist one another.

cPanel Only: If you don’t feel confident doing any of this yourself, or if you would like a comprehensive security service for your server, we do have cPanel Server Services that include the installation and configuration of this application.