syslog-ng Open Source Edition 3.18 - Administration Guide

The Apache Access Log Parser

The Apache Access Log Parser can parse the access log messages of the Apache HTTP Server. The syslog-ng OSE application can separate these log messages to name-value pairs. For details on using value-pairs in syslog-ng OSE see Structuring macros, metadata, and other value-pairs. The apache-accesslog-parser() supports both the Common Log Format and the Combined Log Format of Apache (for details, see the Apache HTTP Server documentation). The following is a sample log message:

127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326

The syslog-ng OSE application extracts every field into name-value pairs, and adds the .apache. prefix to the name of the field.

parser parser_name {
    apache-accesslog-parser(
        prefix()
    );
};

The parser extracts the following fields from the messages: clientip, ident, auth, timestamp, rawrequest, response, bytes, referrer, and agent. The rawrequest field is further segmented into the verb, request, and httpversion fields. The syslog-ng OSE apache-accesslog-parser() parser uses the same naming convention as Logstash.

source s_apache {
    file(/var/log/access_log);
};

destination d_json {
    file(
        "/tmp/test.json"
        template("$(format-json .apache.*)\n")
    );
};

log {
    source(s_apache);
    parser { apache-accesslog-parser();};
    destination(d_json);
};

To use this parser, the scl.conf file must be included in your syslog-ng OSE configuration:

@include "scl.conf"

The apache-accesslog-parser() is actually a reusable configuration snippet configured parse Apache access log messages. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of this configuration snippet on GitHub.

Options of apache-accesslog-parser() parsers

The apache-accesslog-parser() has the following options.

parser {
    apache-accesslog-parser(prefix("apache."));
};

template()

Description: The macro that contains the part of the message that the parser will process. It can also be a macro created by a previous parser of the log path. By default, the parser processes the entire message (${MESSAGE}).

The Cisco Parser

The Cisco Parser can parse the log messages of various Cisco devices. The messages of these devices often do not completely comply with the syslog RFCs, making them difficult to parse. The cisco-parser() of syslog-ng OSE solves this problem, and can separate these log messages to name-value pairs, extracting also the Cisco-specific values, for example, the mnemonic. For details on using value-pairs in syslog-ng OSE see Structuring macros, metadata, and other value-pairs. The parser can parse variations of the following message format:

<pri>(sequence: )?(origin-id: )?(timestamp? timezone?: )?%msg

For example:

<189>29: foo: *Apr 29 13:58:40.411: %SYS-5-CONFIG_I: Configured from console by console
<190>30: foo: *Apr 29 13:58:46.411: %SYS-6-LOGGINGHOST_STARTSTOP: Logging to host 192.168.1.239 stopped - CLI initiated
<190>31: foo: *Apr 29 13:58:46.411: %SYS-6-LOGGINGHOST_STARTSTOP: Logging to host 192.168.1.239 started - CLI initiated
<189>32: 0.0.0.0: *Apr 29 13:59:12.491: %SYS-5-CONFIG_I: Configured from console by console

Note that not every Cisco log message conforms to this format. If you find a message that the cisco-parser() cannot properly parse, send it to documentation@balabit.com so we can improve the parser.

The syslog-ng OSE application normalizes the parsed log messages into the following format:

${MESSAGE}=%FAC-SEV-MNEMONIC: message
${HOST}=origin-id

By default, the Cisco-specific fields are extracted into the following name-value pairs:${.cisco.facility}, ${.cisco.severity}, ${.cisco.mnemonic}. You can change the prefix using the prefix option.

@version: 3.18
@include "scl.conf"
log {
    source { udp(flags(no-parse)); };
    parser { cisco-parser(); };
    destination { ... };
};

Note that you have to disable message parsing in the source using the flags(no-parse) option for the parser to work.

The cisco-parser() is actually a reusable configuration snippet configured to parse Cisco messages. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of this configuration snippet on GitHub.

parser {
    cisco-parser(prefix("myprefix."));
};

The Linux Audit Parser

The Linux Audit Parser can parse the log messages of the Linux Audit subsystem (auditd). The syslog-ng OSE application can separate these log messages to name-value pairs. For details on using value-pairs in syslog-ng OSE see Structuring macros, metadata, and other value-pairs. The following is a sample log message of auditd:

type=SYSCALL msg=audit(1441988805.991:239): arch=c000003e syscall=59 success=yes exit=0 a0=7fe49a6d0e98 a1=7fe49a6d0e40 a2=7fe49a6d0e80 a3=2 items=2 ppid=3652 pid=3660 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=5 comm="dumpe2fs" exe="/sbin/dumpe2fs" key=(null)
type=EXECVE msg=audit(1441988805.991:239): argc=3 a0="dumpe2fs" a1="-h" a2="/dev/sda1"
type=CWD msg=audit(1441988805.991:239):  cwd="/"
type=PATH msg=audit(1441988805.991:239): item=0 name="/sbin/dumpe2fs" inode=137078 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 nametype=NORMAL
type=PATH msg=audit(1441988805.991:239): item=1 name="/lib64/ld-linux-x86-64.so.2" inode=5243184 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 nametype=NORMAL
type=PROCTITLE msg=audit(1441988805.991:239): proctitle=64756D7065326673002D68002F6465762F73646131

Certain fields of the audit log can be encoded in hexadecimal format, for example, the arch field, or the a<number> fields in the previous example. The &abbrev; application automatically decodes these fields (for example, the c000003e value becomes x86_64).

The syslog-ng OSE application extracts every field into name-value pairs. It automatically decodes the following fields:

• name

• proctitle

• path

• dir

• comm

• ocomm

• data

• old

• new

To parse the log messages of the Linux Audit subsystem, define a parser that has the linux-audit-parser() option. By default, the parser will process the ${MESSAGE} part of the log message. To process other parts of a log message, use the template() option. You can also define the parser inline in the log path.

parser parser_name {
    linux-audit-parser(
        prefix()
        template()
    );
};

source s_auditd {
    file(/var/log/audit/audit.log flags(no-parse));
};

destination d_json {
    file(
        "/tmp/test.json"
        template("$(format-json .auditd.*)\n")
    );
};

parser p_auditd {
    linux-audit-parser (prefix(".auditd."));
};

log {
    source(s_auditd);
    parser(p_auditd);
    destination(d_json);
};

source s_auditd {
    file(/var/log/audit/audit.log);
};

destination d_json {
    file(
        "/tmp/test.json"
        template("$(format-json .auditd.*)\n")
    );
};

log {
    source(s_auditd);
    parser {
        linux-audit-parser (prefix(".auditd."));
    };
    destination(d_json);
};