Difference between revisions of "Very Secure FTP Daemon"
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The option below should be set in {{Filename|/etc/vsftpd.conf}}: | The option below should be set in {{Filename|/etc/vsftpd.conf}}: | ||
− | pam_service_name= | + | pam_service_name=ftp |
Finally, add xinetd to your daemons line in {{Filename|/etc/rc.conf}}. You do not need to add vsftpd, as it will be called by xinetd whenever necessary. | Finally, add xinetd to your daemons line in {{Filename|/etc/rc.conf}}. You do not need to add vsftpd, as it will be called by xinetd whenever necessary. |
Revision as of 23:21, 5 September 2011
vsftpd (Very Secure FTP Daemon) is a lightweight, stable and secure FTP server for UNIX-like systems.
Installation
Vsftpd is included in the official repository. Simply install it with pacman:
# pacman -S vsftpd
The server can be started by using the script below:
# /etc/rc.d/vsftpd start
You can also add vsftpd to your daemon array in Template:Filename if you want it to be started automatically at boot.
See the xinetd section below for procedures to use vsftpd with xinetd.
Configuration
Most of the settings in vsftpd are done by editing the file Template:Filename. The file itself is well-documented, so this section only highlights some important changes you may want to modify. For all available options and documentation, one can man vsftpd.conf (5).
Enabling uploading
The Template:Codeline flag must be set to YES in Template:Filename in order to allow changes to the filesystem, such as uploading:
write_enable=YES
Local user logging
One must set the line to Template:Filename to allow users in Template:Filename to login:
local_enable=YES
Anonymous logging
The line in Template:Filename controls whether anonymous users can login:
anonymous_enable=YES # Allow anonymous login no_anon_password=YES # No password is required for an anonymous login anon_max_rate=30000 # Maximum transfer rate for an anonymous client in bytes per second
Chroot jail
One can set up a chroot environment which prevents the user from leaving its home directory. To enable this, add the following lines to Template:Filename:
chroot_list_enable=YES chroot_list_file=/etc/vsftpd.chroot_list
The Template:Codeline variable specifies the file which contains users that are jailed.
For a more restricted environment, one can specify the line:
chroot_local_user=YES
This will make local users jailed by default. In this case, the file specified by Template:Codeline lists users that are not in a chroot jail.
Limiting user login
It's possible to prevent users from logging into the FTP server by adding two lines to Template:Filename:
userlist_enable=YES userlist_file=/etc/vsftpd.user_list
Template:Codeline now specifies the file which lists users that are not able to login.
If you only want to allow certain users to login, add the line:
userlist_deny=NO
The file specified by Template:Codeline will now contain users that are able to login.
Limiting connections
One can limit the data transfer rate, number of clients and connections per IP for local users by adding the information in Template:Filename:
local_max_rate=1000000 # Maximum data transfer rate in bytes per second max_clients=50 # Maximum number of clients that may be connected max_per_ip=2 # Maximum connections per IP
Using xinetd
If you want to use vsftpd with xinetd, add the following lines to Template:Filename:
service ftp { socket_type = stream wait = no user = root server = /usr/sbin/vsftpd log_on_success += HOST DURATION log_on_failure += HOST disable = no }
The option below should be set in Template:Filename:
pam_service_name=ftp
Finally, add xinetd to your daemons line in Template:Filename. You do not need to add vsftpd, as it will be called by xinetd whenever necessary.
If you get errors like this while connecting to the server:
500 OOPS: cap_set_proc
You need to add capability in MODULES= line in Template:Filename.
While upgrading to version 2.1.0 you might get an error like this when connecting to the server from a client:
500 OOPS: could not bind listening IPv4 socket
In earlier versions it has been enough to leave the following lines commented:
# Use this to use vsftpd in standalone mode, otherwise it runs through (x)inetd # listen=YES
In this newer version, and maybe future releases, it is necessary however to explicitly configure it to not run in a standalone mode, like this:
# Use this to use vsftpd in standalone mode, otherwise it runs through (x)inetd listen=NO
Using SSL to Secure FTP
Generate an SSL Cert, e.g. like that:
# cd /etc/ssl/certs # openssl req -x509 -nodes -days 7300 -newkey rsa:2048 -keyout /etc/ssl/certs/vsftpd.pem -out /etc/ssl/certs/vsftpd.pem # chmod 600 /etc/ssl/certs/vsftpd.pem
You will be asked alot of Questions about your Company etc., as your Certificate is not a trusted one it doesn't really matter what you fill in. You will use this for encryption! If you plan to use this in a matter of trust get one from a CA like thawte, verisign etc.
edit your configuration Template:Filename
#this is important ssl_enable=YES #choose what you like, if you accept anon-connections # you may want to enable this # allow_anon_ssl=NO #choose what you like, # it's a matter of performance i guess # force_local_data_ssl=NO #choose what you like force_local_logins_ssl=YES #you should at least enable this if you enable ssl... ssl_tlsv1=YES #choose what you like ssl_sslv2=YES #choose what you like ssl_sslv3=YES #give the correct path to your currently generated *.pem file rsa_cert_file=/etc/ssl/certs/vsftpd.pem #the *.pem file contains both the key and cert rsa_private_key_file=/etc/ssl/certs/vsftpd.pem
Tips and tricks
PAM with virtual users
Using virtual users has the advantage of not requiring a real login account on the system. Keeping the environment in a container is of course a more secure option.
A virtual users database has to be created by first making a simple text file like this:
user1 password1 user2 password2
Include as many virtual users as you wish according to the structure in the example. Save it as logins.txt; the file name does not have any significance. Next step depends on Berkeley database system, which is included in the core system of Arch. As root create the actual database with the help of the logins.txt file, or what you chose to call it:
# db_load -T -t hash -f logins.txt /etc/vsftpd_login.db
It is recommended to restrict permissions for the now created Template:Filename file:
# chmod 600 /etc/vsftpd_login.db
PAM should now be set to make use of vsftpd_login.db. To make PAM check for user authentication create a file named ftp in the Template:Filename directory with the following information:
auth required pam_userdb.so db=/etc/vsftpd_login crypt=hash account required pam_userdb.so db=/etc/vsftpd_login crypt=hash
Now it is time to create a home for the virtual users. In the example Template:Filename is decided to host data for virtual users, which also reflects the default directory structure of Arch. First create the general user virtual and make Template:Filename its home:
# useradd -d /srv/ftp virtual
Make virtual the owner:
# chown virtual:virtual /srv/ftp
Configure vsftpd to use the created environment by editing /etc/vsftpd.conf. These are the necessary settings to make vsftpd restrict access to virtual users, by user-name and password, and restrict their access to the specified area Template:Filename:
anonymous_enable=NO local_enable=YES chroot_local_user=YES guest_enable=YES guest_username=virtual virtual_use_local_privs=YES
If the xinetd method is used start the service. You should now only be allowed to login by user-name and password according to the made database.
Adding private folders for the virtual users
First create directories for users:
# mkdir /srv/ftp/user1 # mkdir /srv/ftp/user2 # chown virtual:virtual /srv/ftp/user?/
Then, add the following lines to Template:Filename:
local_root=/srv/ftp/$USER user_sub_token=$USER