mod_log_forensic
The mod_log_forensic module "captures" log messages generated
by proftpd, for all sorts of log destinations, even if those
log messages would otherwise not be written out, and buffers them
in memory. When certain criteria are met (e.g. failed logins,
segfaults, etc), the mod_log_forensic module will flush
the buffered log messages out to a file. Installation instructions are
discussed here.
The most current version of mod_log_forensic can be found at:
http://www.castaglia.org/proftpd/
Please contact TJ Saunders <tj at castaglia.org> with any questions, concerns, or suggestions regarding this module.
<VirtualHost>, <Global>
The ForensicLogBufferSize directives configures the count
of log messages that mod_log_forensic will buffer. It is
effectively the count of the last count log messages you wish to
see logged, when one of the
ForensicLogCriteria are met.
<VirtualHost>, <Global>
The ForensicLogCapture directive configures which log types
the mod_log_forensic module "captures" for later writing. By
default, mod_log_forensic captures messages for all log types.
The supported log types are:
Unspec
This "type" covers any unspecified/unknown log, e.g. module-specific
log files such as SFTPLog, SQLLogFile,
TLSLog, etc.
TransferLog
syslog
SystemLog
ExtendedLog
TraceLog
<VirtualHost>, <Global>
The ForensicLogCriteria directive configures the criteria
which determine when mod_log_forensic will flush its buffered
log messages out to the configured
ForensicLogFile. Multiple
criteria can be specified.
The currently supported criteria are:
FailedLogin
The buffered log messages will be written to the
ForensicLogFile if the login fails for any reason.
UntimelyDeath
If a session dies prematurely, e.g. due to a segfault or other
internal error, the buffered log messages will be written to the
ForensicLogFile.
ModuleConfig
If a session dies due to a module-specific policy, the buffered log
messages will be written to the ForensicLogFile.
<VirtualHost>, <Global>
The ForensicLogEngine directive enables or disables the
mod_log_forensic module.
<VirtualHost>, <Global>
The ForensicLogFile directive configures a file used for logging
by mod_log_forensic. The configured file must be an
absolute path.
Note that this directive is required for
mod_log_forensic to function properly.
mod_log_forensic, copy the
mod_log_forensic.c into the third-party module directory in
the proftpd source code:
# cp mod_log_forensic.c proftpd-dir/contrib/after unpacking the latest proftpd-1.3.x source code. For including
mod_log_forensic as a staticly linked module:
./configure --with-modules=mod_log_forensic ...Alternatively,
mod_log_forensic can be built as a DSO module:
./configure --enable-dso --with-shared=mod_log_forensic ...Then follow the usual steps:
make make install
Example mod_log_forensic configuration:
<IfModule mod_log_forensic.c>
ForensicLogEngine on
ForensicLogFile /path/to/forensic.log
</IfModule>
For a failed login, the configured ForensicLogFile will
contain a block of log lines, e.g.:
-----BEGIN FAILED LOGIN FORENSICS----- Client-Address: 127.0.0.1 Server-Address: ::ffff:127.0.0.1:5376 Raw-Bytes-In: 46 Raw-Bytes-Out: 158 Total-Bytes-In: 0 Total-Bytes-Out: 0 Total-Files-In: 0 Total-Files-Out: 0 ... [syslog:7, PID 16044] dispatching CMD command 'PASS (hidden)' to mod_auth [syslog:7, PID 16044] retrieved UID 1000 for user 'tj' [syslog:7, PID 16044] retrieved group IDs: 1000, 0, 4, 20, 24, 46, 108, 109, 110 [syslog:7, PID 16044] retrieved group names: tj, root, adm, dialout, cdrom, plugdev, lpadmin, sambashare, admin [syslog:7, PID 16044] ROOT PRIVS at mod_auth_pam.c:312 [syslog:7, PID 16044] RELINQUISH PRIVS at mod_auth_pam.c:482 [syslog:7, PID 16044] ROOT PRIVS at mod_auth_unix.c:467 [syslog:7, PID 16044] RELINQUISH PRIVS at mod_auth_unix.c:548 [SystemLog:5] familiar proftpd[15509] localhost (localhost[127.0.0.1]): USER tj (Login failed): Incorrect password. [syslog:7, PID 16044] dispatching POST_CMD_ERR command 'PASS (hidden)' to mod_delay [syslog:7, PID 16044] dispatching LOG_CMD_ERR command 'PASS (hidden)' to mod_log -----END FAILED LOGIN FORENSICS-----For sessions which suffer an "untimely death", the begin/end markers in the
ForensicLogFile are:
-----BEGIN UNTIMELY DEATH FORENSICS----- Client-Address: 127.0.0.1 Server-Address: ::ffff:127.0.0.1:5376 Raw-Bytes-In: 46 Raw-Bytes-Out: 158 Total-Bytes-In: 0 Total-Bytes-Out: 0 Total-Files-In: 0 Total-Files-Out: 0 ... -----END UNTIMELY DEATH FORENSICS-----
Advantages
What's the big deal with this module? What advantage does it provide
over the normal proftpd logging? The advantage is that with
mod_log_forensic, you do not have to configure ProFTPD to use
verbose logging (i.e. high DebugLevel and/or
Trace levels). If ProFTPD generated a log message internally
but that log message was filtered, then that log message would not
normally be written to disk -- but mod_log_forensic buffers
that log message anyway.
To see this, simply use the following in your proftpd.conf:
TraceLog /path/to/ftpd/trace.log
Trace DEFAULT:0
<IfModule mod_log_forensic.c>
ForensicLogEngine on
ForensicLogFile /path/to/ftpd/forensic.log
</IfModule>
This configured proftpd for trace logging, but turns the
trace logging levels down to zero so that normally, nothing would be written
in the configured TraceLog file.
Now attempt to log into proftpd, deliberately using a wrong/bad
password (or unknown user). The mod_log_forensic module will
write out all of the trace logging messages
(and the other SystemLog/syslog messages) to the
ForensicLogFile, even though the debug level is at the default
level of zero, and the trace levels are all zero. Thus you get the verbose
logging needed to help diagnose failed logins and such, without having
the verbose logging enabled all of the time.