Intrusion Prevention - SSH

SSHGuard – protects hosts from brute-force attacks against SSH and other services

SSHGuard is an intrusion prevention system that parses server logs, determines malicious activity, and uses the system firewall to block the IP addresses of malicious connections.

SSHGuard protects hosts from brute-force attacks against SSH and other services. It aggregates system logs and blocks repeat offenders using one of several firewall backends, including iptables, ipfw, and pf.

The software runs on a machine as a small daemon, and receives log messages (in a number of ways, e.g. from syslog). When it determines that address X did something bad to service Y, it fires a rule in the machine’s firewall (one of the many supported) for blocking X.

SSHGuard keeps X blocked for some time, then releases it automatically.

Features include:

  • Easy to set up, simple one-line command to use
  • Touchiness and automatic blacklisting.
  • Full IPv6 support.
  • Monitor multiple log files at once and handles log rotation and temporary log files automatically.
  • Small system footprint.
  • Sophisticated whitelisting.
  • Recognizes many logging formats transparently.
  • Handles host names or addresses in log files.
  • Supports the following log formats: cockpit, Common Log Format, macOS log , metalog, multilog, raw log files, syslog, syslog-ng, and systemd journal
  • Recognizes attacks against: OpenSSH, Sendmail, Exim, Dovecot, Cucipop, UWimap (IMAP, POP), vsftpd, Postfix, proftpd, pure-ftpd, and FreeBSD ftpd.
  • Integrates with the following firewall backends: FirewallID, ipfw, IPFILTER, netfilter/iptables, netfilter/ipset, PF, tcpd’s host.allow, and IBM AIX’s firewall.
  • Simple, extensible firewall interface.

Support: Documentation, SourceForge Project Site, Git repository
Developer: Mij
License: BSD License

SSHGuard is written in C. Learn C with our recommended free books and free tutorials.

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