| Net::SFTP::SftpServer(3pm) | User Contributed Perl Documentation | Net::SFTP::SftpServer(3pm) |
Net::SFTP::SftpServer - A Perl implementation of the SFTP subsystem with user access controls
use Net::SFTP::SftpServer; my $sftp = Net::SFTP::SftpServer->new(); $sftp->run();
A Perl port of sftp-server from openssh providing access control on a per user per command basis and improved logging via syslog
The limitations compared with the openssh implementation are as follows:
Basic usage:
use Net::SFTP::SftpServer;
Import options:
:LOG - Import logging functions for use in callbacks :ACTION - Import constants for Allow/Deny of actions
Configuring syslog:
Syslog output mode must be configured in the use statement of the module as follows:
use Net::SFTP::SftpServer ( { log => 'local5' }, qw ( :LOG :ACTIONS ) );
Net::SFTP::SftpServer will default to using "daemon" see your system's syslog documentation for more details
Options for object initialisation:
Log debug level information. Deault=0 (note this will create very large log files - use with caution)
Filesystem location of user home directories. default=/home
Octal file permissions to force on creation of files. Default=0666 or permissions specified by file open command from client
Octal dir permissions to force on creation of directories. Default=0777 or permissions specified by mkdir command from client
References to callback functions to be called on complete file sent or received. Function will be passed the full path and filename on the filesystem as a single argument
Use temporary upload filenames while a file is being uploaded - this allows a monitoring script to know which files are in transit without having to watch file size. Will be done transparently to the user, the file will be renamed to the original file name when close. The temportary extension is ".SftpXFR.$$". Default=0
Maximum file size (in bytes) which can be uploaded. Default=0 (no limit)
Array of valid characters for filenames
Actions allowed or denied - see "PERMISSIONS" for details, Default is to allow ALL.
Array of actions (see action contants in "PERMISSIONS") which will be given response SSH2_FX_OK instead of SSH2_FX_PERMISSION_DENIED when denied by above deny options. Default=[]
Array of actions to log quietly (logDetail - syslog debug level), logs messages whenever this action is performed. Default is quiet for SSH2_FXP_READ, SSH2_FXP_WRITE, SSH2_FX_OPENDIR, SSH2_FXP_READDIR, SSH2_FXP_CLOSE, SSH2_FXP_STAT SSH2_FXP_FSTAT and SSH2_FXP_LSTAT override with log_action, see below.
Array of actions to log loudly (logGeneral - syslog info level), logs messages whenever this action is performed.
Log all status messages at info level. By default SSH2_FX_OK and SSH2_FX_EOF will be logged at debug level.
ALL - All actions NET_SFTP_SYMLINKS - Symlinks in paths to files (recommended deny to enforce chroot) NET_SFTP_RENAME_DIR - Rename directories (recommended deny if also denying SSH2_FXP_MKDIR) SSH2_FXP_OPEN SSH2_FXP_CLOSE SSH2_FXP_READ SSH2_FXP_WRITE SSH2_FXP_LSTAT SSH2_FXP_STAT_VERSION_0 SSH2_FXP_FSTAT SSH2_FXP_SETSTAT - Automatically denied, not implemented in module SSH2_FXP_FSETSTAT - Automatically denied, not implemented in module SSH2_FXP_OPENDIR SSH2_FXP_READDIR SSH2_FXP_REMOVE SSH2_FXP_MKDIR SSH2_FXP_RMDIR SSH2_FXP_STAT SSH2_FXP_RENAME SSH2_FXP_READLINK - Automatically denied, not implemented in module SSH2_FXP_SYMLINK - Automatically denied, not implemented in module
Callback functions can be used to perform actions when files are sent or received, for example move a fully downloaded file to a processed directory or move a received file into an input directory. The callback is proided with a Net::SFTP::SftpServer::File object. This object allows access to the file within the virtual chroot environment. It will also return the full filename, or move the file to an explicit location on the full filesystem. Either of these actions will break the chroot and the methods on the object will no longer be available.
The following methods are provided
Read the data from the file - as the IO::File->read. Will open the file for reading if it is not already open and read back the data.
Will open the file - as IO::File->open but the filename is not supplied.
Will return the filename as within the virtual chroot
Will return the full filename on the real file system and break the virtual chroot
Takes a single argument of the new filename, will rename the file to that location and break the virtual chroot
If :LOG is used when including Net::SFTP::SftpServer the following logging functions will be available:
logError - syslog with a log level of error logWarning - syslog with a log level of warning logGeneral - syslog with a log level of info logDetail - syslog with a log level of debug, unless object was created with debug=>1 then syslog with a level of info
The following example script shows how this module can be used to give far greater control over what is allowed on your SFTP server.
This setup is aimed at admins which want to user SFTP uploads but do not wish to grant users a system account. You will also need to set both the SFTP subsystem and the user's shell to the sftp script, eg /usr/local/bin/sftp-server.pl
This configuration:
#!/usr/local/bin/perl
use strict;
use warnings;
use Net::SFTP::SftpServer ( { log => 'local5' }, qw ( :LOG :ACTIONS ) );
use BSD::Resource; # for setrlimit
use constant DEBUG_USER => {
SFTPTEST => 1,
};
# Security - make sure we have started this as sftp not ssh
unless ( scalar @ARGV == 2 and
$ARGV[0] eq '-c' and
($ARGV[1] eq '/usr/local/bin/sftp-server.pl') ){
logError "SFTP connection attempted for application $ARGV[0] - exiting";
print "\n\rYou do not have permission to login interactively to this host.\n\r\n\rPlease contact the system administrator if you believe this to be a configuration error.\n\r";
exit 1;
}
my $MEMLIMIT = 100 * 1024 * 1024; # 100 Mb
# hard limits on process memory usage;
setrlimit( RLIMIT_RSS, $MEMLIMIT, $MEMLIMIT );
setrlimit( RLIMIT_VMEM, $MEMLIMIT, $MEMLIMIT );
my $debug = (defined DEBUG_USER->{uc(getpwuid($>))} and DEBUG_USER->{uc(getpwuid($>))}) ? 1 : 0;
my $sftp = Net::SFTP::SftpServer->new(
debug => $debug,
home => '/var/upload/sftp',
file_perms => 0660,
on_file_sent => \&ActionOnSent,
on_file_received => \&ActionOnReceived,
use_tmp_upload => 1,
max_file_size => 200 * 1024 * 1024,
valid_filename_char => [ 'a' .. 'z', 'A' .. 'Z', '0' .. '9', '_', '.', '-' ],
deny => ALL,
allow => [ (
SSH2_FXP_OPEN,
SSH2_FXP_CLOSE,
SSH2_FXP_READ,
SSH2_FXP_WRITE,
SSH2_FXP_LSTAT,
SSH2_FXP_STAT_VERSION_0,
SSH2_FXP_FSTAT,
SSH2_FXP_OPENDIR,
SSH2_FXP_READDIR,
SSH2_FXP_REMOVE,
SSH2_FXP_STAT,
SSH2_FXP_RENAME,
)],
fake_ok => [ (
SSH2_FXP_SETSTAT,
SSH2_FXP_FSETSTAT,
)],
);
$sftp->run();
sub ActionOnSent {
my $fileObject = shift;
## Do Stuff
}
sub ActionOnReceived {
my $fileObject = shift;
## Do Stuff
}
Stat::lsMode Fcntl POSIX Sys::Syslog Errno
Sftp protocol <http://www.openssh.org/txt/draft-ietf-secsh-filexfer-02.txt>
Simon Day, Pirum Systems Ltd cpan <at> simonday.info
Based on sftp-server.c Copyright (c) 2000-2004 Markus Friedl. All rights reserved.
Ported to Perl and extended by Simon Day Copyright (c) 2009 Pirum Systems Ltd. All rights reserved.
Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
| 2022-12-04 | perl v5.36.0 |