Bruteblock allows system administrators to block various bruteforce attacks on UNIX services. The program analyzes system logs and adds attackers' IP addresses into the ipfw2 table, effectively blocking them. Addresses are automatically removed from the table after specified amount of time. Bruteblock uses regular expressions to parse logs, which gives it enough flexibility to be used with almost any network service. Bruteblock doesn't use any external programs and works with ipfw2 tables via the raw sockets API.