Description

The syslog2iptables.conf configuration file is specified by this partial bnf description. The entire config file is case sensitive. All the keywords are lower case.

CONFIG     = {CONTEXT ";"}+
CONTEXT    = "context" NAME "{" {STATEMENT}+ "}"
STATEMENT := (THRESHOLD | ADD-CMD | REM-CMD | IGNORE | FILE) ";"
THRESHOLD := "threshold" THRESHOLD-INTEGER-VALUE
ADD-CMD   := "add_command" IPT-CMD
REM-CMD   := "remove_command" IPT-CMD
IGNORE    := "ignore" "{" IG-SINGLE+ "}"
IG-SINGLE := IP-ADDRESS "/" CIDR-BITS
FILE      := "file" FILENAME "{" PATTERN+ "}"
PATTERN   := "pattern" REGULAR-EXPRESSION "{" {INDEX | BUCKET | MESSAGE}+ "};"
INDEX     := "index" REGEX-INTEGER-VALUE ";"
BUCKET    := "bucket" BUCKET-ADD-INTEGER-VALUE ";"
MESSAGE   := "message" REASON ";"
REASON    := string to appear in syslog messages
IPT-CMD   := string containing exactly one %s replacement token for
             the ip address

Sample

context dns {
    threshold 1100;

    add_command    "/sbin/iptables -I INPUT --protocol udp --destination-port 53 --src %s --jump DROP";
    remove_command "/sbin/iptables -D INPUT --protocol udp --destination-port 53 --src %s --jump DROP";

    ignore {
        127.0.0.0/8;        // localhost
    };

    file "/var/log/messages" {
        pattern "named.*client (.*)#.*query.*cache.*denied" {
            index 1;    // zero based
            bucket 400;
            message "DNS attack";
        };
    };
};


context general {
    threshold 550;

    add_command    "/sbin/iptables -I INPUT --src %s --jump DROP";
    remove_command "/sbin/iptables -D INPUT --src %s --jump DROP";

    ignore {
        127.0.0.0/8;        // localhost
    };

    file "/var/log/secure" {
        pattern "sshd.*Failed password .* from ::ffff:(.*) port" {
            index 1;    // zero based
            bucket 400;
            message "ssh failed password";
        };
        pattern "sshd.*Failed password .* from (.*) port" {
            index 1;    // zero based
            bucket 400;
            message "ssh failed password";
        };
        pattern "proftpd.*no such user found from (.*) \[" {
            index 1;    // zero based
            bucket 400;
            message "ftp failed password";
        };
    };

    file "/var/log/messages" {
        pattern "ipop3d.* Login failed .* \[(.*)\]" {
            index 1;    // zero based
            bucket 400;
            message "pop3 failed password";
        };
    };

    file "/var/log/httpd/access_log" {
        // of course you cannot use this if you actually use cgi-bin directories
        pattern "(.*) - - .* /cgi-bin" {
            index 1;    // zero based
            bucket 400;
            message "apache cgi-bin reference";
        };
        // or if you actually have an index2.php script
        pattern "(.*) - - .*/index2.php" {
            index 1;    // zero based
            bucket 400;
            message "apache index2.php reference";
        };
        // or if you have a main.php script
        pattern "(.*) - - .*/main.php" {
            index 1;    // zero based
            bucket 400;
            message "apache main.php reference";
        };
        pattern "(.*) - - .*/awstats.pl" {
            index 1;    // zero based
            bucket 400;
            message "apache awstats.pl reference";
        };
        pattern "(.*) - - .*/adxmlrpc" {
            index 1;    // zero based
            bucket 400;
            message "apache adxmlrpc reference";
        };
    };

    file "/var/log/maillog" {
        pattern "lost input channel from .* \[(.*)\] .* after (mail|rcpt|auth)" {
            index 1;    // zero based
            bucket 200;
            message "sendmail spammer dropping connection";
        };
        pattern " \[(.*)\]: possible SMTP attack" {
            index 1;    // zero based
            bucket 600;
            message "sendmail authentication attack";
        };
        pattern "rejecting commands from .* \[(.*)\] due to pre-greeting traffic" {
            index 1;    // zero based
            bucket 200;
            message "sendmail pre-greeting";
        };
        pattern "dovecot.*Aborted login.*rip=(.*)," {
            index 1;    // zero based
            bucket 100;
            message "dovecot failed password";
        };
        pattern "dovecot: pop3-login: Disconnected: Shutting down.*rip=(.*)," {
            index 1;    // zero based
            bucket 100;
            message "dovecot failed password";
        };

        // make sure your upstream MX servers are listed in the
        // ignore block above, otherwise you will kill them off
        // when they try to forward such mail to you.
        pattern "sendmail.*from=<>,.*nrcpts=0,.*\[(.*)\]" {
            index 1;    // zero based
            bucket 200;
            message "sendmail rejected bounce";
        };
    };
};

Version

1.13