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ProFTPD module mod_lang
ProFTPD module mod_lang
Internalization and Localization
The mod_lang module is ProFTPD's module for handling the
LANG and OPTS UTF8 commands, in support of
RFC 2640. The
mod_lang module also supports character sets other than UTF-8,
for those sites which do not require RFC 2640 support, but do use
character sets other than ASCII. This module is contained in the
mod_lang.c file for ProFTPD 1.3.x, and is compiled in
whenever the --enable-nls configure option is used. Installation
instructions are discussed here. Examples
of using mod_lang for various encodings and character sets can
be seen here.
The most current version of mod_lang can be found in the
ProFTPD source distribution.
Directives
Syntax: LangDefault language
Default: LangDefault en_US
Context: server config, <VirtualHost>, <Global>
Module: mod_lang
Compatibility: 1.3.1rc1
The LangDefault directive is used to specify the default
language of specific server configuration. Note that the specified language
must be listed in the output from:
$ locale -a
Example:
<IfModule mod_lang.c>
# Set the default to be Italian
LangDefault it_IT
</IfModule>
Syntax: LangEngine on|off
Default: LangEngine on
Context: server config, <VirtualHost>, <Global>
Module: mod_lang
Compatibility: 1.3.1rc1
The LangEngine directive enables or disables the module's
handling of the LANG command. If it is set to off this
module does no localization of responses.
Note that setting LangEngine to off also keeps
proftpd from advertisting "UTF8" in its FEAT response.
As required by RFC 2640, proftpd can only show "UTF8"
in response to a FEAT command if the LANG command
is also supported. Hence why it is the LangEngine directive,
and not UseUTF8, which controls the appearance of "UTF8".
Syntax: LangOptions opt1 ...
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_lang
Compatibility: 1.3.6rc1 and later
The LangOptions directive is used to configure various optional
behavior of mod_lang.
Example:
LangOptions PreferServerEncoding
The currently implemented options are:
PreferServerEncoding
This option will cause mod_lang to refuse any
OPTS UTF8 commands used by clients; these commands are
used to change the server's handling of UTF8 encoded filenames.
Note that this option replaces the previous "strict" keyword
supported by the UseEncoding directive, in older versions
of mod_lang.
RequireValidEncoding
This option will cause proftpd to reject commands
on filenames if those filenames, as sent by the client, are not properly
encoded in the expected character set.
Syntax: LangPath path
Default: None
Context: server config
Module: mod_lang
Compatibility: 1.3.1rc1
The LangPath directive is used to configure an alternative
directory from which mod_lang will load locale files. By
default, mod_lang uses $prefix/locale/,
where $prefix is where you installed proftpd,
e.g. /usr/local/.
The path parameter must be an absolute path.
Example:
LangPath /etc/proftpd/locale
Example:
LangPath /path/to/ftpd/locale
Syntax: UseEncoding on|off|local-charset client-charset
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_lang
Compatibility: 1.3.2rc1
The UseEncoding directive is used to explicitly configure which
character sets should be used for encoding. By default, the
mod_lang module will automatically discover the local character
set, and will use UTF-8 for the client character set. The module will also
allow the use of UTF-8 encoding to be changed by clients using the
OPTS UTF8 command (as per RFC 2640).
For example, to disable all use of encoding, use the following in your
proftpd.conf:
UseEncoding off
Similarly, to enable use of UTF8 encoding and to not allow clients
to change the use of UTF8, you would use:
UseEncoding on
In addition to the on|off parameters, the UseEncoding
directive allows administrators to specify exactly which character sets
to use locally (i.e. for paths on local disks) and for dealing with
clients. One such usage this way might look like:
UseEncoding koi8-r cp1251
With the above, a client could still request a switch from koi8-r
encoding to UTF-8 via the OPTS UTF8 command. If, however, you
wished to prevent clients from changing the encoding to UTF-8, the above
configuration would instead look like:
LangOptions PreferServerEncoding
UseEncoding koi8-r cp1251
For a full list of the character sets which are supported, use:
$ iconv --list
The mod_lang module is distributed with ProFTPD. To enable use
of NLS (Natural Language Support) in your proftpd daemon, use the
--enable-nls configure option:
$ ./configure --enable-nls
$ make
$ make install
This option causes mod_lang to be compiled into
proftpd.
One common request of proftpd is to properly handle Cyrillic
characters in file and directory names. The usual character sets which
contain Cyrillic characters use the same codes as used for Telnet
control codes, unfortunately.
RFC 959 (which defines FTP)
mandates that the Telnet control codes be supported in FTP implementations.
The mod_lang module, however, can be used to deal with this
situation. If the
UseEncoding directive is used to
translate between local and client character sets, and the client
character set is one of the known Cyrillic character sets, then
proftpd will disable support of the Telnet control codes.
To make a long explanation short, if you want to use Cyrillic characters
in paths with proftpd, compile your proftpd
using the --enable-nls configure option (to enable the use
of mod_lang), then use something like the following in your
proftpd.conf:
<IfModule mod_lang.c>
UseEncoding utf8 cp1251
</IfModule>
The current list of character sets for which Telnet code support is disabled
is listed below; the names are not case-sensitive:
- cp866
- cp1251
- iso-8859-1
- koi8-r
- windows-1251
Frequently Asked Questions
Question: What translations for proftpd currently exist?
Answer: ProFTPD has currently been translated into:
- bg_BG
- en_US
- es_ES
- fr_FR
- it_IT
- ja_JP
- ko_KR
- ru_RU
- zh_CN
- zh_TW
If you are interested in providing more translations, please read this
howto.
Question: When I upload a file with special characters
(e.g. umlauts, accents, cedillas, etc) in the file name, the
special characters are turned into '?' on the server. What's wrong?
Answer: There are a couple of things to check when
this happens.
First, make sure that your proftpd has been compiled with NLS
support. Type proftpd -V, and make sure you see:
+ NLS support
appear in the output.
Next, make sure that the LANG environment variable is set before
starting the server. Special characters require that UTF-8 or ISO-8859-1 be
used, thus you might use things like:
# export LANG=de_DE.utf8
# export LANG=fr_FR.ISO8859-1
Last, check that any routers/firewalls/NAT between the clients and the server
are not interfering. ProFTPD lists "UTF8" in its FEAT response
data; many FTP clients use the OPTS UTF8 ON command to inform the
server that UTF8 filenames will be sent. Some routers, firewalls, and NATs
have been known to filter both the FEAT response and/or block
commands like OPTS UTF8, thus interfering with the protocol and
causing encoding problems.
Question: I have configured my mod_lang
module to use a language, but when I start proftpd, I see an
error like this:
mod_lang/0.9: LangDefault 'language', configured for server 'serverName', is not a supported language, removing
Answer: This usually happens for one of two reasons:
- The configured language is not listed in
`setlocale -a'
- The configured language is not one of the supported translations
Both of these conditions must be true, otherwise you will see the
"not a supported language" error.
© Copyright 2006-2017 TJ Saunders
All Rights Reserved
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