audit.log files are the depository for audit records stored locally or on an audit server. These files are kept in directories named in the file audit_control(4). They are named to reflect the time they are created and are, when possible, renamed to reflect the time they are closed as well. The name takes the form

yyyymmddhhmmss.not_terminated.hostname

when open or if the auditd(1M) terminated ungracefully, and the form

yyyymmddhhmmss.yyyymmddhhmmss.hostname

when properly closed. yyyy is the year, mm the month, dd day in the month, hh hour in the day, mm minute in the hour, and ss second in the minute. All fields are of fixed width.

The audit.log file begins with a standalone file token and typically ends with one also. The beginning file token records the pathname of the previous audit file, while the ending file token records the pathname of the next audit file. If the file name is NULL the appropriate path was unavailable.

The audit.log files contains audit records. Each audit record is made up of audit tokens. Each record contains a header token followed by various data tokens. Depending on the audit policy in place by auditon(2), optional other tokens such as trailers or sequences may be included.

The tokens are defined as follows:

The file token consists of:

token ID 1 byte seconds of time 4 bytes milliseconds of time 4 bytes file name length 2 bytes file pathname N bytes + 1 terminating NULL byte

The header token consists of:

token ID 1 byte record byte count 4 bytes version # 1 byte [2] event type 2 bytes event modifier 2 bytes seconds of time 4 bytes/8 bytes (32-bit/64-bit value) milliseconds of time 4 bytes/8 bytes (32-bit/64-bit value)

The expanded header token consists of:

toke ID 1 byte record byte count 4 bytes version # 1 byte [2] event type 2 bytes event modifier 2 bytes address type/length 4 bytes/16 bytes (IPv4/IPv6 address) machine address 4 bytes/16 bytes (IPv4/IPv6 address) seconds of time 4 bytes/8 bytes (32/64-bits) milliseconds of time 4 bytes/8 bytes (32/64-bits)

The trailer token consists of:

token ID 1 byte trailer magic number 2 bytes record byte count 4 bytes

The arbitrary data token is defined:

token ID 1 byte how to print 1 byte basic unit 1 byte unit count 1 byte data items (depends on basic unit)

The in_addr token consists of:

token ID 1 byte internet address 4 bytes

The expanded in_addr token consists of:

token ID 1 byte IP address type/length 4 bytes/16 bytes (IPv4/IPv6 address) IP address 16 bytes

The ip token consists of:

token ID 1 byte version and ihl 1 byte type of service 1 byte length 2 bytes id 2 bytes offset 2 bytes ttl 1 byte protocol 1 byte checksum 2 bytes source address 4 bytes destination address 4 bytes

The expanded ip token consists of:

token ID 1 byte version and ihl 1 byte type of service 1 byte length 2 bytes id 2 bytes offset 2 bytes ttl 1 byte protocol 1 byte checksum 2 bytes address type/type 4 bytes source address 4 bytes/16 bytes (IPv4/IPv6 address) address type/length 4 bytes/16 bytes (IPv4/IPv6 address) destination address 4 bytes/16 bytes (IPv4/IPv6 address)

The iport token consists of:

token ID 1 byte port IP address 2 bytes

The path token consists of:

token ID 1 byte path length 2 bytes path N bytes + 1 terminating NULL byte

The process token consists of:

token ID 1 byte audit ID 4 bytes effective user ID 4 bytes effective group ID 4 bytes real user ID 4 bytes real group ID 4 bytes process ID 4 bytes session ID 4 bytes terminal ID port ID 4 bytes/8 bytes (32-bit/64-bit value) machine address 4 bytes

The expanded process token consists of:

token ID 1 byte audit ID 4 bytes effective user ID 4 bytes effective group ID 4 bytes real user ID 4 bytes real group ID 4 bytes process ID 4 bytes session ID 4 bytes terminal ID port ID 4 bytes/8 bytes (32-bit/64-bit value) address type/length 4 bytes/16 bytes (IPv4/IPv6 address) machine address 16 bytes

The return token consists of:

token ID 1 byte error number 1 byte return value 4 bytes/8 bytes (32-bit/64-bit value)

The subject token consists of:

token ID 1 byte audit ID 4 bytes effective user ID 4 bytes effective group ID 4 bytes real user ID 4 bytes real group ID 4 bytes process ID 4 bytes session ID 4 bytes terminal ID port ID 4 bytes/8 bytes (32-bit/64-bit value) machine address 4 bytes

The expanded subject token consists of:

token ID 1 byte audit ID 4 bytes effective user ID 4 bytes effective group ID 4 bytes real user ID 4 bytes real group ID 4 bytes process ID 4 bytes session ID 4 bytes terminal ID port ID 4 bytes/8 bytes (32-bit/64-bit value) address type/length 4 bytes/16 bytes (IPv4/IPv6 address) machine address 16 bytes

The System V IPC token consists of:

token ID 1 byte object ID type 1 byte object ID 4 bytes

The text token consists of:

token ID 1 byte text length 2 bytes text N bytes + 1 terminating NULL byte

The attribute token consists of:

token ID 1 byte file access mode 4 bytes owner user ID 4 bytes owner group ID 4 bytes file system ID 4 bytes node ID 8 bytes device 4 bytes/8 bytes (32-bit/64-bit)

The groups token consists of:

token ID 1 byte number groups 2 bytes group list N * 4 bytes

The System V IPC permission token consists of:

token ID 1 byte owner user ID 4 bytes owner group ID 4 bytes creator user ID 4 bytes creator group ID 4 bytes access mode 4 bytes slot sequence # 4 bytes key 4 bytes

The arg token consists of:

token ID 1 byte argument # 1 byte argument value 4 bytes/8 bytes (32-bit/64-bit value) text length 2 bytes text N bytes + 1 terminating NULL byte

The exec_args token consists of:

token ID 1 byte count 4 bytes text count null-terminated string(s)

The exec_env token consists of:

token ID 1 byte count 4 bytes text count null-terminated string(s)

The exit token consists of:

token ID 1 byte status 4 bytes return value 4 bytes

The socket token consists of:

token ID 1 byte socket type 2 bytes remote port 2 bytes remote Internet address 4 bytes

The expanded socket token consists of:

token ID 1 byte socket domain 2 bytes socket type 2 bytes local port 2 bytes address type/length 4 bytes/16 bytes (IPv4/IPv6 address) local port 2 bytes local Internet address 4 bytes/16 bytes (IPv4/IPv6 address) remote port 2 bytes remote Internet address 4 bytes/16 bytes (IPv4/IPv6 address)

The seq token consists of:

token ID 1 byte sequence number 4 bytes

audit(1M), auditd(1M), bsmconv(1M), audit(2), auditon(2), au_to(3BSM), audit_control(4)

Each token is generally written using the au_to(3BSM) family of function calls.

The functionality described in this man page is available only if the Basic Security Module (BSM) has been enabled. See bsmconv(1M) for more information.