Difference between revisions of "Server"
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==== Accessibility ====
==== Accessibility ====
is the '''S'''ecure '''SH'''ell, it allows you to remotely connect to your server and administer commands as if you were physically at the computer. Combined with [[Screen]], SSH can become an invaluable tool for remote maintenence and administration while on-the-move. Please note that a standard SSH install is not very secure and some configuration is needed before the server can be considered locked-down. This configuration includes disabling root login, disabling password based login and setting up firewall rules. In addition, you may supplement the security of your SSH daemon by utilizing daemons such as [[
is the '''S'''ecure '''SH'''ell, it allows you to remotely connect to your server and administer commands as if you were physically at the computer. Combined with [[Screen]], SSH can become an invaluable tool for remote maintenence and administration while on-the-move. Please note that a standard SSH install is not very secure and some configuration is needed before the server can be considered locked-down. This configuration includes disabling root login, disabling password based login and setting up firewall rules. In addition, you may supplement the security of your SSH daemon by utilizing daemons such as [] or [[fail2ban]] which constantly monitor the log files for any suspicious activity and ban IP addresses with too many failed logins.
Revision as of 10:11, 23 July 2011Template:Box Note
- 1 Preface
- 2 Requirements
- 3 Basic set-up
- 4 Additional web-services
- 5 Local Network Services
- 6 Security
- 7 Administration and maintenance
- 8 Extras
- 9 More Resources
What is a server?
In essence, a server is a computer that runs services that involve clients working on remote locations. All computers run services of some kind, for example: when using Arch as a desktop you will have a network service running to connect to a network. A server will, however, run services that involve external clients, for example: a webserver will run a website to be viewed via the internet or elsewhere on a local network.
Why would I want a server?
There are various reasons you may want a server. You may want to create a website for a company or you may wish to have an internal database for your network. Maybe you need a central fileserver for your home-network? This guide will give you an overview for the most common server options in existence and will outline some administration and security guidelines.
Arch Linux as a server OS
You may have seen the comments or claims: Arch Linux was never intended as a server operating system! This is correct: The basic installation includes very few server features and there is no server installation disc available. This does not mean it's not possible, quite the contrary. Arch's core installation is a secure and capable foundation. Because of the low amount of things that come pre-installed, this core installation can easily be used as a basis for a Linux Server. Many applications and services you would want on a server (such as apache, sql and samba) are available in the repository and are well documented on the wiki.
For using Arch Linux on a server you will need to have an Arch Linux installation ready.
In most Linux server Operating Systems you have 2 options:
- A 'text' version of the OS (where everything is done from the command line)
- A GUI version of the OS (where you get a desktop interface such as GNOME/KDE etc).
So what is a "basic" set-up:
- Remote access to the server.
We want to be able to remotely log-on to our server to perform several administrative tasks. When your server is located elsewhere or does not have a monitor attached: removing or adding files, changing configuration options and server rebooting are all tasks which are impossible to do without a way to log on to your server remotely. SSH nicely provides this functionallity.
- Your Linux server.
- A http server (Apache), required for serving webpages.
- A database server (MySql), often required for storing data of address book-, forum- or blog scripts.
- The PHP scripting language, a highly popular internet scripting language used in blogs, forums, content management systems and many other web-scripts.
As the bold letters suggest, there is a name for this combination of applications: LAMP.
The following sections will guide you through the installation and confgiuration of the above mentionned basic set-up features.
SSH stands for Secure Shell. SSH enables you to log on to your server through an SSH client, presenting you with a recognizable terminal-like interface.Users available on the system can be given access to log on remotely though SSH, thereby enabeling remote administration of your server.
The Arch wiki SSH page covers Installation and Configuration nicely.
A LAMP server is a reasonably standard webserver.
There are often disputes as to what the 'P' stands for, some people say it is php some people say it is perl while others say it's python. For the purposes of this guide I am going to make it php, although there are some nice perl modules for linux so you may wish to install perl as well.
Having said that, LAMP is a reasonably standard webserver, it is by no means simple so there may be a lot to take in here.
Please refer to the LAMP wiki page for instructions on installation and configuration.
Please refer to the EXIM wiki page for instructions on installation and configuration.
FTP stands for File Transfer Protocol. FTP is a service that can provide access to the filesystem from a remote location through an FTP client (FileZilla, gftp etc.) or FTP-capable browser. Through FTP, you are able to add or remove files from a remote location, as well as apply some chmod commands to these files to set certain permissions.
FTP access will be related to user accounts available on the system, allowing simple rights management. FTP is a much used tool for adding files to a webserver from a remote locations.
There are several FTP daemons available, here follows a list of Arch Linux Wiki pages on a few:
- vsFTPd: Very Secure FTP Daemon (oftend the standard)
- glFTPd: GreyLine FTP daemon (highly configurable, no system accounts required)
- proFTPd: Article is incomplete.
There is also the option of FTP over SSH, or SFTP
Local Network Services
CUPS, or Common UNIX Printing System, can provide a central point via which a number of users can print. For instance, you have several (say 3) printers and several people on a local network that wish to print. You can either add all these printers to every user's pc, or add all printers to a server running CUPS, and then simply adding the server to all clients. This allows for a central printing system that can be online 24/7, especially nice for printers that do not have networking capabillities.
Please refer to the CUPS wiki page for instructions on installation and configuration.
Samba (windows compatible file- and printer sharing)
Samba is an open source implementation of SBM/CIFS networking protocols, effectively allowing you to share files and printers between Linux and Windows systems. Samba can provide public shares or require several forms of authentification.
Please refer to the Samba wiki page for instructions on installation and configuration.
The linux kernel includes iptables as a built-in firewall solution. Configuration may be managed directly through the userspace utilities or by installing one of several gui configuation tools. As a minimum, you will want to install the userspace programs:
# pacman -S iptables
In addition, you should add the iptables daemon to start on boot to your rc.conf
DAEMONS=(... iptables network ...)
The Uncomplicated FireWall is a simple frontend to iptables for the command line. It is available in the Template:Codeline repository. One way to allow SSH and HTTP access after installation would be:
# ufw allow SSH/tcp # ufw allow WWW/tcp # ufw enable
To view other preconfigured services and apps run
# ufw app list
A GUI frontend to UFW is available providing simple management of your iptables rules and settings. It is available in the Template:Codeline repository. To install and run use the following commands:
# pacman -S gufw # gufw
Allowing remote log-on through SSH is good for administrative purposes, but can pose a threat to your server's security. Often the target of brute force attacks, SSH access needs to be limited properly to prevent third parties gaining access to your server.
- Use non-standard account names and passwords
- Only allow incoming SSH connections from trusted locations
- Use fail2ban or sshguard to monitor for brute force attacks, and ban brute forcing IPs accordingly
Limiting access to SSH
Firstly, let us check if our installation of Arch Linux is secure in terms of allowing external parties access to services on our server. The /etc/hosts.deny file should look like this:
ALL: ALL: DENY
This means that ALL hosts are DENIED ACCESS to ALL services on the system. Now, to actually allow remote hosts access to the services on our server, we should edit the counterpart of hosts.deny called hosts.allow.
The SSH wiki article mentions editing /etc/hosts.allow to allow outside connections to the SSH daemon.
# let everyone connect to you sshd: ALL # OR you can restrict it to a certain ip sshd: 192.168.0.1 # OR restrict for an IP range sshd: 10.0.0.0/255.255.255.0 # OR restrict for an IP match sshd: 192.168.1.
You may not always know beforehand from what location you will be accessing your server. However, if you do know (i.e. you will be accessing your headless server from your desktop system with a fixed IP), it is wise to allow access only from these known locations.
If you want more broad access to your server through SSH, from any location at any given time, you will have to allow ALL. This poses a threat, opening your SSH daemon for connections from anyone. These third parties will then be able to try and log in through means of brute force: continuously trying to log on with random user names and password combinations.
Protecting against brute force attacks
Brute forcing is a simple concept: One continuously tries to log in to a webpage or server log-in prompt like SSH with a high number of random username and password combinations. You can protect yourself from brute force attacks by using an automated script that blocks anybody trying to brute force their way in, for example fail2ban or sshguard.
Deny root login
It is generally considered bad practice to allow the user root to log in over SSH: The root account will exist on nearly any linux system and grants full access to the system, once login has been acchieved. Sudo provides root rights for actions requiring these and is the more secure solution, third parties would have to find a username present on the system, the matching password and the matching password for sudo to get root rights on your system. More barries to be breached before full access to the system is reached.
Configure SSH to deny remote logins with the root user by editing (as root) /etc/sshd/sshd_config and look for this section:
# Authentication: #LoginGraceTime 2m #PermitRootLogin yes #StrictModes yes #MaxAuthTries 6 #MaxSessions 10
Now simply change #PermitRootLogin yes to no, uncomment the line and restart the SSH daemon:
You will now be unable to log in through SSH under root, but will still be able to log in with your normal user and use su - or sudo to do system administration.
Please refer to the SELinux wiki page for instructions on installation and configuration, the page is only a stub, if you use SELinux you are on your own.
Administration and maintenance
SSH is the Secure SHell, it allows you to remotely connect to your server and administer commands as if you were physically at the computer. Combined with Screen, SSH can become an invaluable tool for remote maintenence and administration while on-the-move. Please note that a standard SSH install is not very secure and some configuration is needed before the server can be considered locked-down. This configuration includes disabling root login, disabling password based login and setting up firewall rules. In addition, you may supplement the security of your SSH daemon by utilizing daemons such as sshguard or fail2ban which constantly monitor the log files for any suspicious activity and ban IP addresses with too many failed logins.
X Forwarding is forwarding your X session via SSH so you can login to the desktop GUI remotely. Use of this feature will require SSH and an X server to be installed on the server. You will also need to have a working X server installed on the client system you will be using to connect to the server with. More information can be found in the X Forwarding section of the SSH guide.
"phpMyAdmin is a free software tool written in PHP intended to handle the administration of MySQL over the World Wide Web. phpMyAdmin supports a wide range of operations with MySQL. The most frequently used operations are supported by the user interface (managing databases, tables, fields, relations, indexes, users, permissions, etc), while you still have the ability to directly execute any SQL statement." http://www.phpmyadmin.net/home_page/index.php