Ubuntu – Create FTP users with limited access only to home directory Ubuntu 12.04

This document may help you understanding how permissions should be applied for your files/folders in order to Wordpress work without a hassle.

In my personal experience, giving 755 permissions to the WordPress folder does the trick, but certain folders will require to have 777 no matters what WordPress says, several plugins and/or updates (even to the WP core) won't work if those folders doesn't feature 777 permissions.

Quoted from the document that I mention in the top of this answer:

1. All files should be owned by the actual user's account, not the user account used for the httpd process.
2. Group ownership is irrelevant, unless there's specific group requirements for the web-server process permissions checking. This is not usually the case.
3. All directories should be 755 or 750.
4. All files should be 644 or 640. Exception: wp-config.php should be 600 to prevent other users on the server from reading it.
5. No directories should ever be given 777, even upload directories. Since the php process is running as the owner of the files, it gets the owners permissions and can write to even a 755 directory.

This answer: General Rules for dealing with File Permissions will be helpful for a better comprehension on the permissions in a Ubuntu based system. Which -in case to be a local server- won't need to be accessed through a FTP Client in order to perform the task, but using a terminal.

If you need further information about this, feel free to drop a comment. My WP Blog can be reached via http://geppettvs.x10.mx/blog and I faced this issue lots of times in the past for remote and local servers.

Glossary for my answer:

1. Local Server should be considered a computer that I can plug with a keyboard or mouse in order to interact directly with its OS.
2. Remote Server is a computer that is not physically in front of me and I can't plug a keyboard or mouse to it in order to work with the computer's OS.

With a bit of playing around I've managed to come up with a semi solution (not perfect but good enough)

using 2707974 answer and information I've gained else where I've been able to get what I need.

First you need vsftp and PAM installed

apt-get install vsftpd libpam-pwdfile

Edit /etc/vsftpd.conf

nano /etc/vsftpd.conf

then paste in the following

listen=YES
anonymous_enable=NO
local_enable=YES
write_enable=YES
local_umask=022
local_root=/var/www
chroot_local_user=YES
allow_writeable_chroot=YES
hide_ids=YES

#virutal user settings
user_config_dir=/etc/vsftpd_user_conf
guest_enable=YES
virtual_use_local_privs=YES
pam_service_name=vsftpd
nopriv_user=vsftpd
guest_username=vsftpd

Edit to your exact needs the most important bit for virtual users is everything after the virtual user settings comment

Creating User

You can either use a database or htpasswd I found htpasswd faster and easier to use.

make a directory to store your users

mkdir /etc/vsftpd
htpasswd -cd /etc/vsftpd/ftpd.passwd user1

adding additional users just omit the -c

htpasswd -d /etc/vsftpd/ftpd.passwd user2

I've only managed to get it to work using CRYPT which limits to 8 chars to use more than 8 chars use openssl to generate a compatible hash and pipe directly into htpasswd

htpasswd -c -p -b /etc/vsftpd/ftpd.passwd user1 $(openssl passwd -1 -noverify password)

Once your users are created you can now change your PAM config file

nano /etc/pam.d/vsftpd

and remove everything inside this file and replace with the following

auth required pam_pwdfile.so pwdfile /etc/vsftpd/ftpd.passwd
account required pam_permit.so

This will enable login for your virtual users defined in /etc/vsftpd/ftpd.passwd and will disable local users

Next we need to add a user for these virtual users to use. These users will not have access to the shell and will be called vsftpd

useradd --home /home/vsftpd --gid nogroup -m --shell /bin/false vsftpd

the user must match guest_username=vsftpd in the vsftpd conf file

Defining Directory Access

The important line here is the following

user_config_dir=/etc/vsftpd_user_conf

this means that when user1 logs in it will look for the following file

/etc/vsftpd_user_conf/user1

this file the same as the vsftpd.conf so you can define a new local_root

going back to the question we want user1 to only have access to var/www/website_name1/sub_folder1, so we need to create the vsftpd_user_conf folder:

mkdir /etc/vsftpd_user_conf

Now create the user file:

nano /etc/vsftpd_user_conf/user1

and enter the following line

local_root=/var/www/website_name1/sub_folder1

Now restart vsftp

service vsftpd restart

you should now be able to login as user1 who will only be able to see var/www/website_name1/sub_folder1 and any folder and file inside it.

That's it you can now add as many users as you want and limit their access to whatever folder you wish.

important to remember if you do not create a user conf file it will default to the var/www folder as root (in the example above)

If the subfolder is intended to be modifiable by the user, it might be necesary to change the owner of the shared subfolder:

chown vsftpd:nogroup /var/www/website_name1/sub_folder1