ProFTPD module mod_log



This module is contained in the mod_log.c file for ProFTPD 1.3.x, and is compiled by default.

Directives


AllowLogSymlinks

Syntax: AllowLogSymlinks on|off
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_log
Compatibility: 1.2.2rc2 and later

By default, the server will the path of any configured SystemLog, any configured TransferLogs, and any configured ExtendedLogs to see if they are symbolic links. If the paths are symbolic links, proftpd will refuse to log to that link unless explicitly configured to do so via this AllowLogSymlinks directive.

Security Note: This behaviour should not be allowed unless for a very good reason. By allowing the server to open symbolic links with its root privileges, you are allowing a potential symlink attack where the server could be tricked into overwriting arbitrary system files. You have been warned.


ExtendedLog

Syntax: ExtendedLog path [cmd-classes [format-name]]
Default: None
Context: server config, <VirtualHost>, <Global>, <Anonymous>
Module: mod_log
Compatibility: 1.1.6p11 and later

The ExtendedLog directive allows customizable logfiles to be generated, either globally or per <VirtualHost>. The path argument should contain an absolute pathname to a logfile which will be appended to when proftpd starts; the pathname should not be to a file in a nonexistent directory, to a world-writable directory, or be a symbolic link (unless AllowLogSymlinks is set to on). Multiple logfiles, potentially with different command classes and formats) can be created. Optionally, the cmd-classes parameter can be used to control which types of commands are logged. If no command classes are specified, proftpd logs all commands by default. Note that passwords are hidden. If used, the cmd-classes parameter is a comma-delimited (with no whitespace) list of which commands to log.

In proftpd-1.2.8rc1 and later, the path argument can be of the form "syslog:level". The "syslog:" prefix configures mod_log to write the ExtendedLog data to syslog rather than to a file. The level configures the syslog level at which to log the data. For example:

  ExtendedLog syslog:info ALL default

This table shows the supported command classes:

Command Class FTP Commands
ALL All commands except the EXIT pseudo-command (default)
NONE No commands
AUTH Authentication commands: ACCT, PASS, REIN, USER
INFO Informational commands: FEAT, HELP, MDTM, QUIT, PWD, STAT, SIZE, SYST, XPWD
DIRS Directory commands: CDUP, CWD, LIST, MKD, MLSD, MLST, NLST, RMD, XCWD, XCUP, XMKD, XRMD
READ File reading: RETR
WRITE File/directory writing or creation: APPE, MFF, MFMT, MKD, RMD, RNFR, RNTO, STOR, STOU, XMKD, XRMD
MISC Miscellaneous commands: ABOR, ALLO, EPRT, EPSV, MODE, NOOP, OPTS, PASV, PORT, REST, RNFR, RNTO, SITE, SMNT, STRU, TYPE
SEC RFC2228-related security FTP commands: AUTH, CCC, PBSZ, PROT
EXIT Logs the configured LogFormat at session exit.
NOTE: EXIT is not part of the ALL command class, in order to preserve backward-compatible ALL behavior.

If a format-name parameter is used, ExtendedLog will use the named LogFormat. Otherwise, the default format of "%h %l %u %t \"%r\" %s %b" is used.

For example, to log all read and write operations to /var/log/ftp.log using the default format, use:

  ExtendedLog /var/log/ftp.log READ,WRITE
and to log all read and write operations to /var/log/ftp.log using your own LogFormat named "custom", use:
  LogFormat custom ...
  ExtendedLog /var/log/ftp.log READ,WRITE custom

See also: AllowLogSymlinks, LogFormat, TransferLog


LogFormat

Syntax: LogFormat format-name format-string
Default: LogFormat default "%h %l %u %t \"%r\" %s %b"
Context: server config
Module: mod_log
Compatibility: 1.1.6p11 and later

The LogFormat directive can be used to create a custom logging format for use with the ExtendedLog directive. Once created, the format can be referenced by the specified format-name. The format-string parameter can consist of any combination of letters, numbers and symbols. The special character '%' is used to start a meta sequence/variable (see below). To insert a literal '%' character, use "%%".

The default LogFormat is:

  "%h %l %u %t \"%r\" %s %b"
which produces log entries in the Common Log Format.

The following meta sequences/variables are available and are replaced as indicated when logging.

Variable Value
 %a  Remote client IP address
 %A  Anonymous login password, or "UNKNOWN" for regular logins
 %{basename}  Last component of path, i.e. just the file or directory name.
 %b  Number of bytes sent for this command
 %c  Client connection class, or "-" if undefined
 %d  Directory name (not full path) for: CDUP, CWD, LIST, MLSD, MKD, NLST, RMD, XCWD, XCUP, XMKD, XRMD
 %D  Directory path (full path) for: CDUP, CWD, LIST, MLSD, MKD, NLST, RMD, XCWD, XCUP, XMKD, XRMD
 %E  End-of-session reason
 %{NAME}e  Contents of environment variable NAME
 %f  Absolute path of the filename stored or retrieved (not chrooted)
 %F  Filename stored or retrieved, as the client sees it
 %{file-modified}  Indicates whether a file is modified (i.e. already exists): "true" or "false"
 %{file-size}  Indicates the file size after data transfer, or "-" if not applicable
 %{gid}  GID of authenticated user
 %g  Primary group of authenticated user
 %h  Remote client DNS name
 %H  Local IP address of vhost/server hosting/handling the session
 %I  Total number of "raw" bytes read in from network
 %{iso8601}  shorthand form of %{%Y-%m-%d %H:%M:%S}t,%{millisecs}, e.g. "2013-01-30 20:14:05,670"
 %J  Command arguments received from client, e.g. "file.txt"
 %l  Remote username (from identd), or "UNKNOWN" if IdentLookup failed
 %L  Local IP address contacted by client
 %m  Command (method) name received from client, e.g. RETR
 %{microsecs}  6 digit value of the microseconds of the current time
 %{millisecs}  3 digit value of the milliseconds of the current time
 %O  Total number of "raw" bytes written out to network
 %p  Local port
 %P  Local server process ID (pid)
 %{protocol}  Current protocol: "ftp", "ftps", "ssh2", "sftp", "scp"
 %r  Full command received from client
 %R  Response time, in milliseconds
 %{remote-port}  Remote client port
 %s  Numeric FTP response code (status); see RFC 959 Section 4.2.1
 %S  Response message sent to client (available since 1.3.1rc1)
 %t  Current local time
 %{format}t  Current local time using strftime(3) format
 %T  Time taken to transfer file, in seconds
 %{transfer-failure}  Reason for data transfer failure (if applicable), or "-"
 %{transfer-millisecs}  Time taken to transfer file, in milliseconds
 %{transfer-status}  Status of data transfer: "success", "failed", "cancelled", "timeout", or "-"
 %{transfer-type}  Data transfer type: "binary" or "ASCII" (if applicable), or "-"
 %u  Authenticated local username
 %U  USER name originally sent by client
 %{uid}  UID of authenticated user
 %v  Local server ServerName
 %V  Local server DNS name
 %{version}  ProFTPD version
 %w  Absolute path for the RNFR path ("whence" a rename comes)

See also: ExtendedLog, TransferLog


ServerLog

Syntax: ServerLog path|"none"
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_log
Compatibility: 1.2.8rc1 and later

The ServerLog directive is used to configure a <VirtualHost>-specific logfile at the given path, rather than a single SystemLog for the entire configuration.

A path value of "none" will disable file logging for that vhost; this can be used to override a global ServerLog setting.


SystemLog

Syntax: SystemLog path|"none"
Default: None
Context: server config
Module: mod_log
Compatibility: 1.1.6p11 and later

The SystemLog directive disables proftpd's use of the syslog mechanism and instead redirects all logging output to the specified path. The path should contain an absolute path, and should not be to a file in a nonexistent directory, in a world-writable directory, or be a symbolic link (unless AllowLogSymlinks is set to on).

Use of this directive overrides any facility set by the SyslogFacility directive.

A path value of "none" will disable logging for the entire daemon.


Installation

The mod_log module is compiled by default.


Usage

Frequently Asked Questions

Question: I have configured ProFTPD to use DNS names in my proftpd.conf using:

  UseReverseDNS on
But in my ExtendedLog, I still see IP addresses rather than the DNS names I expect to see. How can that happen?
Answer: The
LogFormat %h is what is used to log DNS names. The logged value might be an IP address if ProFTPD cannot properly verify that the client IP address resolves to a DNS name.

"Properly verifying" an IP address, in this case, means resolving the DNS name for an IP address and then resolving that DNS name back to its IP addresses:

  $ host 10.1.2.3
  3.2.1.10.in-addr.arpa domain name pointer host.domain.example.com.
  $ host host.domain.example.com
  host.domain.example.com has address 10.4.5.6
In this example, the IP address 10.1.2.3 does not resolve back to itself via DNS, but rather to a different IP address.

If the DNS name does not resolve back to the original IP address, then that DNS name is not used, as that DNS name is considered "unreliable"; only reliable information is logged (and used elsewhere). Thus ProFTPD resorts to logging just the client IP address for the %h variable, rather than the DNS name, in these situations.

Question: How can I get the reason a client was disconnected, for whatever reason, logged to my ExtendedLog?
Answer: You can use the %E LogFormat variable for this, in conjunction with the EXIT log class.

For example, assume you have configured the following:

  MaxConnectionsPerUser 2
and you would like your ExtendedLog to record when this limit is reached. To do this, you would use something like the following:
  LogFormat eos "%a: user=%U disconnect_reason=\"%E\""
  ExtendedLog /var/log/proftpd/ext.log EXIT eos
Of course, you can include other logging classes than just EXIT; the above is just an example.

With the above, when the MaxConnectionsPerUser is reached, your log would have a line like:

  127.0.0.1: user=tj disconnect_reason="Denied by MaxConnectionsPerUser"


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