FTP - Root vs Home Directory

[Kirsle]

This is an interesting phenomenon that I've noticed since Fedora Core 5 and with every subsequent version of Fedora since then (and presumably with other distros too).

If a Fedora server is running vsftpd for FTP, and you use Nautilus on another Linux desktop to connect to it (via typing "ftp://10.10.1.100/" in the address bar for example), you get access to the root directory on the remote server, and would then have to go to "/home/username" to get your home directory.

But, if you FTP from a Windows client via Windows Explorer by putting in the ftp:// path in the address bar, you get a chroot to the user's home directory, and can't get to a higher directory or get to /.

So when I'm away from home and need to get a file that's on my external hard drive (under /media), I have to use a Linux desktop with Nautilus if I want to get the file over FTP, because using Windows Explorer or any regular FTP client (Filezilla, FireFTP) gets me a chroot to my home directory; if I want something under /media, I need to SSH in beforehand and copy the file I want into my home directory first, to get it over FTP.

What does Nautilus do differently? How is it able to get the root directory over FTP instead of being chrooted to the user's home directory as other FTP clients do? Or does it "cheat" and try SFTP if available? (cuz I know with SFTP you can get any directory you want since it uses SSH).

Note: my vsftpd.conf is pretty much the default that comes with vsftpd:

# Example config file /etc/vsftpd/vsftpd.conf
#
# The default compiled in settings are fairly paranoid. This sample file
# loosens things up a bit, to make the ftp daemon more usable.
# Please see vsftpd.conf.5 for all compiled in defaults.
#
# READ THIS: This example file is NOT an exhaustive list of vsftpd options.
# Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's
# capabilities.
#
# Allow anonymous FTP? (Beware - allowed by default if you comment this out).
anonymous_enable=NO
#
# Uncomment this to allow local users to log in.
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
write_enable=YES
#
# Default umask for local users is 077. You may wish to change this to 022,
# if your users expect that (022 is used by most other ftpd's)
local_umask=022
#
# Uncomment this to allow the anonymous FTP user to upload files. This only
# has an effect if the above global write enable is activated. Also, you will
# obviously need to create a directory writable by the FTP user.
#anon_upload_enable=YES
#
# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES
#
# Activate directory messages - messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES
#
# Activate logging of uploads/downloads.
xferlog_enable=YES
#
# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES
#
# If you want, you can arrange for uploaded anonymous files to be owned by
# a different user. Note! Using "root" for uploaded files is not
# recommended!
#chown_uploads=YES
#chown_username=whoever
#
# You may override where the log file goes if you like. The default is shown
# below.
#xferlog_file=/var/log/vsftpd.log
#
# If you want, you can have your log file in standard ftpd xferlog format.
# Note that the default log file location is /var/log/xferlog in this case.
xferlog_std_format=YES
#
# You may change the default value for timing out an idle session.
#idle_session_timeout=600
#
# You may change the default value for timing out a data connection.
#data_connection_timeout=120
#
# It is recommended that you define on your system a unique user which the
# ftp server can use as a totally isolated and unprivileged user.
#nopriv_user=ftpsecure
#
# Enable this and the server will recognise asynchronous ABOR requests. Not
# recommended for security (the code is non-trivial). Not enabling it,
# however, may confuse older FTP clients.
#async_abor_enable=YES
#
# By default the server will pretend to allow ASCII mode but in fact ignore
# the request. Turn on the below options to have the server actually do ASCII
# mangling on files when in ASCII mode.
# Beware that on some FTP servers, ASCII support allows a denial of service
# attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd
# predicted this attack and has always been safe, reporting the size of the
# raw file.
# ASCII mangling is a horrible feature of the protocol.
#ascii_upload_enable=YES
#ascii_download_enable=YES
#
# You may fully customise the login banner string:
#ftpd_banner=Welcome to blah FTP service.
#
# You may specify a file of disallowed anonymous e-mail addresses. Apparently
# useful for combatting certain DoS attacks.
#deny_email_enable=YES
# (default follows)
#banned_email_file=/etc/vsftpd/banned_emails
#
# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
#chroot_list_enable=YES
# (default follows)
#chroot_list_file=/etc/vsftpd/chroot_list
#
# You may activate the "-R" option to the builtin ls. This is disabled by
# default to avoid remote users being able to cause excessive I/O on large
# sites. However, some broken FTP clients such as "ncftp" and "mirror" assume
# the presence of the "-R" option, so there is a strong case for enabling it.
#ls_recurse_enable=YES
#
# When "listen" directive is enabled, vsftpd runs in standalone mode and 
# listens on IPv4 sockets. This directive cannot be used in conjunction 
# with the listen_ipv6 directive.
listen=YES
#
# This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6
# sockets, you must run two copies of vsftpd whith two configuration files.
# Make sure, that one of the listen options is commented !!
#listen_ipv6=YES

pam_service_name=vsftpd
userlist_enable=YES
tcp_wrappers=YES

Cuvou.com | My personal homepage

perl -e '$|=$i=1;print" oo\n<|>\n_|_";x:sleep$|;print"\b",$i++%2?"/":"_";goto x;'

 

[sleipnir214]

You're not chrooting anybody. What you're likely seeing is that some FTP client remember the last directory you were in on a site and automatically take you back there on successive logins.

As a matter of course, I change this section of vsftpd.conf:

[tt]# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
#chroot_list_enable=YES
# (default follows)
#chroot_list_file=/etc/vsftpd/chroot_list[/tt]


to read:

[tt]# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
chroot_local_user=YES
chroot_list_enable=NO
# (default follows)
#chroot_list_file=/etc/vsftpd/chroot_list[/tt]

That way every user is chrooted when logging in via FTP.


Want to ask the best questions? Read Eric S. Raymond's essay "How To Ask Questions The Smart Way". TANSTAAFL!

 

[Kirsle]

It's not an issue of an FTP client remembering the last directory I was in, since connecting a new FTP client to the server for the first time still chroots me to my home directory, and there is no "../" parent directory option... i.e. the "/" directory on FTP is my home directory, not the root directory.

The intention isn't to chroot all users, I'd actually prefer that all FTP clients get access to /, since this is a personal PC with only one user and it's convenient if I'm away from home, stuck with a Windows PC that doesn't have any SCP/SFTP clients or anything fancy installed, and need to get files that are under /media. If the remote PC is Linux running GNOME, I can just use FTP over Nautilus and get to the root directory, or use SFTP or SCP to get the files; FTP on Windows Explorer or any regular FTP client chroots me to my home directory for no reason and doesn't let me get to the root directory.

Cuvou.com | My personal homepage

perl -e '$|=$i=1;print" oo\n<|>\n_|_";x:sleep$|;print"\b",$i++%2?"/":"_";goto x;'

 

[sleipnir214]

To the best of my knowledge, vsftpd has no provision for selectively chrooting a user based on his FTP client. If some clients don't give you access to /, it could be because they're programmed to assume they're chrooted.

Anyway, it's generally a bad idea to let FTP users wander around across the entire filesystem. When multiple users must access a common directory structure, I user the "--bind" option of the mount command to make it available in the chrooted user's home directory.


Want to ask the best questions? Read Eric S. Raymond's essay "How To Ask Questions The Smart Way". TANSTAAFL!