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 ";"
DELTA     := "bucket" BUCKET-DELTA-INTEGER ";"
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 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 "manual unblock (.*)" {
            index 1;    // zero based
            bucket -5000;
            message "manual unblock";
        };
        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 "sshd.*authentication failure; .* rhost=(.*) " {
            index 1;    // zero based
            bucket 400;
            message "ssh failed password";
        };
        pattern "sshd.*Did not receive identification string from (.*)" {
            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";
        };
        pattern "proftpd.* authentication failure; .* rhost=(.*) " {
            index 1;    // zero based
            bucket 400;
            message "ftp failed password";
        };
        pattern "vsftpd.* authentication failure; .* rhost=(.*) " {
            index 1;    // zero based
            bucket 400;
            message "ftp failed password";
        };
        pattern "dovecot.* authentication failure; .* rhost=::ffff:(.*) " {
            index 1;    // zero based
            bucket 100;
            message "dovecot failed password";
        };
        pattern "dovecot.* authentication failure; .* rhost=(.*) " {
            index 1;    // zero based
            bucket 100;
            message "dovecot failed password";
        };
    };

    file "/var/log/messages" {
        pattern "dovecot.* authentication failure; .* rhost=(.*) " {
            index 1;    // zero based
            bucket 100;
            message "dovecot failed password";
        };
        pattern "kernel.*local-net-to.*SRC=(.*) DST=.*DPT=" {
            index 1;    // zero based
            bucket 400;
            message "kernel firewall blocked packet";
        };
        pattern "kernel.*outside-net-from.*SRC=(.*) DST=.*DPT=" {
            index 1;    // zero based
            bucket 400;
            message "kernel firewall blocked packet";
        };
    };

    file "/var/log/maillog" {
        pattern "lost input channel from.* \[(.*)\] .* after (mail|rcpt|auth)" {
            index 1;    // zero based
            bucket 100;
            message "sendmail spammer dropping connection";
        };
        pattern " \[(.*)\].* possible SMTP attack" {
            index 1;    // zero based
            bucket 100;
            message "sendmail authentication attack";
        };
        pattern "rejecting commands from.* \[(.*)\] due to pre-greeting traffic" {
            index 1;    // zero based
            bucket 1800;
            message "sendmail pre-greeting";
        };
        pattern "authentication failure: checkpass failed, .*\[(.*)\]" {
            index 1;    // zero based
            bucket 100;
            message "sendmail authentication failed";
        };
        pattern "dovecot.*Aborted login .* rip=(.*)," {
            index 1;    // zero based
            bucket 100;
            message "dovecot failed password";
        };
        pattern "dovecot.*Login: .* rip=(.*)," {
            index 1;    // zero based
            bucket -5000;
            message "dovecot good authentication";
        };
        pattern "sendmail.*AUTH=server, .*\[(.*)\]," {
            index 1;    // zero based
            bucket -5000;
            message "sendmail good authentication";
        };
    };
};

Version

1.20