Δευτέρα, 18 Ιουλίου 2011

FreeBSD Install OpenNTPD NTP Server / Client To Synchronize The Local Clock

How do I install OpenNTPD ( a Unix system daemon implementing the Network Time Protocol) to synchronize the local clock of a FreeBSD computer system with remote NTP servers called ntp.myisp.com?

Accurate time is important for various UNIX applications such as BIND, Crond, Apache and others. OpenNTPD able to act as an NTP server and as an NTP server to NTP-compatible clients. The default ntpd server cannot bind to specific IP address. If you are planning to use FreeBSD jails, you must disable ntpd and use OpenNTPD.

OpenNTPD Installation

Type the following command to update FreeBSD ports tree:
# portsnap fetch update
To install OpenNTPD server, enter:
# cd /usr/ports/net/openntpd
# make install clean

Configuration Files

  1. /usr/local/sbin/ntpd OpenNTPD network server file.
  2. /usr/local/etc/rc.d/openntpd - OpenNTPD startup scripts to start / stop OpenNTPD server.
  3. /usr/local/etc/ntpd.conf - OpenNTPD configuration file.
  4. TCP / UDP port # 123 - OpenNTPD NTP port.
Open /usr/local/etc/ntpd.conf file, enter:
# vi /usr/local/etc/ntpd.conf
Update configuration as follows:
# Do not listen to all IP, just bind
# openntpd to Ipv4 203.11.22.33, 10.21.16.223, IPv6 2607:f0d0:3001:0009:0000:0000:0000:0001
# and loopback
listen on 203.11.22.33
listen on 10.21.16.223
listen on 2607:f0d0:3001:0009:0000:0000:0000:0001
listen on 127.0.0.1
 
# Sync to a single server
server ntp.myisp.com
 
# Use a random selection of 8 public stratum 2 servers
servers pool.ntp.org

Turn on OpenNTPD service

Enable OpenNTPD service:
# echo 'openntpd_enable="YES"' >> /etc/rc.conf

Task: Start OpenNTPD Service

# /usr/local/etc/rc.d/openntpd start

Task: Stop OpenNTPD Service

# /usr/local/etc/rc.d/openntpd stop

Task: Restart OpenNTPD Service

# /usr/local/etc/rc.d/openntpd restart

Task: Verify OpenNTPD Service

Find out the status:
# /usr/local/etc/rc.d/openntpd status
Sample output:
openntpd is running as pid 68596 68597.
Verify open port:
# sockstat -4 -p 123
OR
# sockstat -46 -p 123
Sample output:
_ntp     ntpd       68597 4  udp4   10.21.16.223:61228     10.0.1.22:123
_ntp     ntpd       68597 6  udp4   203.11.22.33:123     *:*
_ntp     ntpd       68597 7  udp4   10.21.16.223:123       *:*
_ntp     ntpd       68597 8  udp6   2607:f0d0:3001:9::1:123*:*
_ntp     ntpd       68597 9  udp4   127.0.0.1:123         *:*
_ntp     ntpd       68597 10 udp4   203.11.22.33:51829   69.31.43.10:123
_ntp     ntpd       68597 11 udp4   203.11.22.33:52453   67.159.5.90:123
_ntp     ntpd       68597 12 udp4   203.11.22.33:58929   71.6.202.221:123
_ntp     ntpd       68597 13 udp4   203.11.22.33:60272   198.144.194.12:123
_ntp     ntpd       68597 14 udp4   203.11.22.33:51298   216.45.57.39:123

Open Outgoing Port Port # 123 via PF firewall

Update your /etc/pf.conf as follows:
# Note $ext_if is your interface facing the Internet
# Useful for dedicated FreeBSD server #
# Ipv4 Open outgoing port TCP 123 (NTP)
pass out on $ext_if proto tcp to any port ntp
 
# Ipv6 Open outgoing port TCP 123 (NTP)
pass out on $ext_if inet6 proto tcp to any port ntp
 
# Ipv4 Open outgoing port UDP 123 (NTP)
pass out on $ext_if proto udp to any port ntp
 
# Ipv6 Open outgoing port UDP 123 (NTP)
pass out on $ext_if inet6 proto udp to any port ntp
Reload pf firewall rules:
# /sbin/pfctl -nf /etc/pf.conf && /etc/rc.d/pf reload Read more...

Παρασκευή, 15 Ιουλίου 2011

Τι είναι το eSATA

Προέρχεται από τα αρχικά External Serial Advanced Technology Attachment ή eSATA είναι η εξωτερική διασύνδεση για την τεχνολογία SATA. Ανταγωνίζεται με το FireWire 400 και με το Universal Serial Bus (USB) 2.0 για να περέχει γρήγορη διασύνδεση για εξωτερικές αποθηκευτικές συσκευές.
Η τεχνολογία SATA αντικατέστησε το το πρώτυπο ΑTA ως η επόμενη γενιά εσωτερική επικοινωνίας για σκληρούς δίσκους (Hard Drives) Το πρωτόκολο SATA είναι πιο σύγχρονο από την τεχνολογία ΑΤΑ και παρέχει πιο μεγάλες ταχύτητες μεταφοράς δεδομένων.Τα καλώδια SATA πιο στενά και μπορούν να έχουν μήκος μέχρισ και 2 μέτρα, σε σχέση με τα παλιά παράλληλα καλώδια που είναι πολύ πιο φαρδιά και δεν μπορούν να είνα πάνω από 46,7 εκατοστά.


Το πρωτόκολο eSATA φτάνει μέχρι τρείς φορές μεγαλύτερη ταχύτητα σε σχέση με το USB 2 και FireWire 400, αλλά έχει και ένα μειονέκτημα, χρειάζεται την δική του τάση τροφοδοσίας, κάτι που δεν χρειάζεται στα άλλα δύο πρωτόκολλα. Παρόλλα αυτά είναι η καλύτερη επιλογή για εξωτερικούς σκληρούς δίσκους. However, it is an excellent choice for external disk storage.
Σε αντίθεση με τα πρωτόκολλα USB και FireWire, το eSATA δεν χρειάζεται να μεταφράσει τα δεδομένα μεταξύ του πρωτόκολου και του υπολογιστή. Το γεγονός αυτό βελτιώνει την ταχύτητα δεδομένων, ενώ γλυτώνει πόρους του συστήματος και εξαφανίζει την ανάγκη για έξτρα τσιπ για μείωση των πόρων.
Για επιταπέζιους υπολογιστές που δεν έχουν σύνδεση eSATA, μπορεί να προστεθεί κάρτα που παρέχει το πρωτόκολλο αυτό. Οι φορητοί (Notebooks) μπορούν να επίσης να χρησιμοποιήσουν μια PCI (Peripheral Component Interconnect) κάρτα. Η τεχνολογία eSATA δίνει την δυνατότητα σε εξωτερικούς σκληρούς δίσκου SATA να χρησιμοποιηθούν ως εξωτερικοί σκληροί δίσκοι με την τεχνολογία SATA.
Η τεχνολογία SATA έχει ή SATA/150, έχει μέγιστη μεταφορά δεδομένων τα 150Megabytes ανά δευτερόλεπτο (MB/s) ενώ οι SATA II ή SATA/3Gba έχει μέγιστη μεταφορά δεδομένων τα 300 ΜΒ/s ή 3 Gbs/s. Ενώ αναμένεται το SATA/600 μέσα στο έτος. Read more...

DIY: How to repair a clicking damaged hard drive

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Hard Drive Recovery

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Liquid Cooled SLi Gaming Computer

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Δευτέρα, 11 Ιουλίου 2011

ΤΑ ΠΑΙΔΙΚΑ ΜΑΣ ΧΡΟΝΙΑ by athinaios1984(hlias)

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RETRO GREEK!!!

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RETRO 80'S GREEK CARTOONS-COMIC-ΣΕΙΡΕΣ-ΤΑΙΝΙΕΣ

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Argoman (Trailer)

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Supersonic Man Ο μοναδικός Supersonic Man

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Prototype 2 E3 2011 Trailer

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Funny Bloopers 2011 LOL !

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FreeBSD Gnome Installation howto

GNOME is a complete desktop environment (no matter what Linus says ;) ). In GNOME, everything is easy to use, and works the way you want.
So how do you install Gnome Desktop system under FreeBSD?
These days it is quite easy to install Gnome Desktop system under FreeBSD. You have following choices (use only one of the method).

Option # 1: Fetch and install Gnome binary package from Internet

To install GNOME 2.16 from binary package over Internet or local FTP server type the command:
# pkg_add -v -r gnome2
Now proceed to post installation instructions.

Option # 2: Install Gnome binary package from CD/DVD

Login as root and type sysinstall:
# sysinstall
Select Configure > Packages > CD/DVD > Gnome
Select all packages and hit install button
Now proceed to post installation instructions.

Option # 3: Install Gnome using FreeBSD ports system

To compile and build Gnome type the following command:
# cd /usr/ports/x11/gnome2
# make clean; make install clean
Read more...

Install GUI in Ubuntu Server

We have already discussed how to install ubuntu 9.04 LAMP server .If you are a new user and not familiar with command prompt you can install GUI for your ubuntu LAMP server using the 2 options

1) Install desktop Environment
2) Install Webmin

1) Install desktop Environment

First you nee to make sure you have enabled Universe and multiverse repositories in /etc/apt/sources.list file once you have enable you need to use the following command to install GUI
sudo apt-get update
sudo apt-get install ubuntu-desktop
The above command will install GNOME desktop
If you wan to install a graphical desktop manager without some of the desktop addons like Evolution and OpenOffice, but continue to use the server flavor kernel use the following command
sudo aptitude install --without-recommends ubuntu-desktop
If you want to install light weight desktop install xfce using the following command
sudo apt-get install xubuntu-desktop
If you want to install KDE desktop use the following command
sudo apt-get install kubuntu-desktop
2) Install Webmin in Ubuntu
Webmin is a web-based interface for system administration for Unix. Using any modern web browser, you can setup user accounts, Apache, DNS, file sharing and much more. Webmin removes the need to manually edit Unix configuration files like /etc/passwd, and lets you manage a system from the console or remotely.Currently There is no Webmin package in the Ubuntu repositories.This tutorial will explain how to Install Webmin in Ubuntu Jaunty
You can install webmin for your server web interface to configure apache2,mysql,FTp servers and many more.Now we will see how to install webmin in Ubuntu 9.04
Preparing your system
First you need to install the following packages
sudo aptitude install perl libnet-ssleay-perl openssl libauthen-pam-perl libpam-runtime libio-pty-perl libmd5-perl
Now download the latest webmin using the following command or from here
wget http://prdownloads.sourceforge.net/webadmin/webmin_1.470_all.deb
Now we have webmin_1.470_all.deb package install this package using the following command
sudo dpkg -i webmin_1.470_all.deb
This will complete the installation.
Using the Webmin APT repository
If you like to install and update Webmin via APT, edit the /etc/apt/sources.list file on your system
sudo vi /etc/apt/sources.list
add the line
deb http://download.webmin.com/download/repository sarge contrib
Save and exit the file
You should also fetch and install my GPG key with which the repository is signed, with the commands : cd /root
wget http://www.webmin.com/jcameron-key.asc
sudo apt-key add jcameron-key.asc
You will now be able to install with the commands
sudo apt-get update
sudo apt-get install webmin
All dependencies should be resolved automatically.
Ubuntu in particular don’t allow logins by the root user by default. However, the user created at system installation time can use sudo to switch to root. Webmin will allow any user who has this sudo capability to login with full root privileges.
Now you need to open your web browser and enter the following
https://your-server-ip:10000/
Now you should see similar to the following Screen

After login if you want to configure Apache,Mysql server you need to click on Servers on your lefthand side you should many servers are ready to configure
This is very Easy to configure most of the servers and Enjoy your new Ubuntu Jaunty LAMP Server. Read more...

A Guide to Today's Top 10 Linux Distributions

1. Ubuntu

Yes, Ubuntu has become the poster child for Linux these days, and no wonder--it's the most popular distro by far, garnering more than 2,200 hits per day on the Distrowatch site alone, compared with some 1,400 for Fedora, the No. 2 contender.
Ubuntu is actually a relatively late arrival on the Linux scene, having been announced in just 2004, but it's more than made up for that shorter history. Founded by South African millionaire Mark Shuttleworth, Canonical--the company behind Ubuntu--for many years shipped Ubuntu CDs to interested users for free, thus speeding its market penetration.
Ubuntu is based on Debian (see below) and includes well-known apps such as Firefox and OpenOffice.org. It has a predictable, six-month release schedule, with occasional Long Term Support (LTS) versions that are supported with security updates for three to five years.
Ubuntu is also notable for its ease of use and its inclusion of a migration assistant for Windows users and support for the latest technologies. Version 10.10 of Ubuntu--also known as Maverick Meerkat--will include a multitouch and gesture stack. The final iteration of that version is due out next month.
It's also worth understanding that Ubuntu is available in various remixes and spin-off sub-distros targeted at specific niches, such as Kubuntu, Xubuntu and Lubuntu. Most of these differ primarily by offering a desktop environment other than Ubuntu's standard GNOME.

2. Fedora

Fedora is the free version of Red Hat, whose RHEL (Red Hat Enterprise Linux) has been a commercial product since 2003. Because of that close connection, Fedora is particularly strong on enterprise features, and it often offers them before RHEL does.
Fedora also offers a six-month release schedule, and its security features are excellent. While some have viewed it as a cutting-edge distro for the Linux "hobbyist," I think improvements over the years and widespread popularity have combined to make it a good choice for newer Linux users as well.

3. Linux Mint

Currently in Distrowatch's third spot in popularity, Linux Mint is an Ubuntu-based distro that was just launched in 2006. The operating system adds to Ubuntu with its own, distinct desktop theme and a different set of applications; also unique to the distro are a variety of graphical tools for enhanced usability, such as mintDesktop for configuring the desktop environment, mintInstall for easier software installation and mintMenu for easier navigation.
Mint enjoys a well-deserved reputation for ease of use, so it's another good one for beginning users. It also includes some proprietary multimedia codecs that are often absent from larger distributions, thereby enhancing its hardware compatibility. Mint doesn't have a fixed release schedule, but typically a new version comes out shortly after each stable Ubuntu release.

4. openSUSE

With some 1,200 hits per day on Distrowatch, openSUSE holds the No. 4 spot in popularity on the site and is also the foundation for Novell's SUSE Linux Enterprise Desktop and SUSE Linux Enterprise Server products.
The package's administration utility, YaST, is widely acknowledged as one of the best, and its boxed edition comes with some of the best printed documentation you'll find for any distro. I'd say openSUSE rates a "medium" on difficulty level.

5. PCLinuxOS

Rather than GNOME, PCLinuxOS uses the KDE desktop environment and is essentially a lighter-weight version of Mandriva (see below). With good support for graphics drivers, browser plugins and media codecs, PCLinuxOS can be a good choice for beginners. Its release cycle can be erratic, though, and there is also no 64-bit version of the software.

6. Debian

Dating back to 1993, Debian is currently known as one of the most well-tested and bug-free distros available today. Though it serves as the foundation for Ubuntu, most view Debian as a distro best-suited for those experienced with Linux. The distro uses all open-source components, which is a good thing, but means it can be more difficult to achieve compatibility with proprietary code such as wireless network drivers. Debian also has a relatively slow release cycle, with stable ones coming out every one to three years.

7. Mandriva

Formerly known as Mandrake, Mandriva is notable for its cutting-edge software, excellent administration suite and 64-bit edition. It was also the first major distribution to jump on the netbook bandwagon with out-of-the box support. Nevertheless, Mandriva has been struggling lately as a result of some controversial decisions made by its French maker. It recently restructured, with the result that some view the future of its community version as uncertain.

8. Sabayon/Gentoo

Italian Sabayon is essentially a LiveCD version of Gentoo, which is known for allowing users to individually optimize each component. Both are considered advanced Linux distributions aimed primarily at experienced users.

9. Arch Linux... plus Slackware

Arch is another package aimed primarily at experienced users interested in tweaking and optimizing their systems. Though not in the top 10 currently, Slackware is similarly oriented toward Linux gurus.

10. Puppy Linux... plus DSL

Last on Distrowatch's top 10 currently is Puppy Linux, a compact distro that's ideal for older hardware and situations where computing resources are minimal. (Damn Small Linux, incidentally, is similar.) Though it has a small footprint, Puppy is still full-featured and includes a variety of configuration and application installation wizards. The whole OS is small enough to run directly from system RAM, so applications start quickly and respond to user input instantly. Read more...

Παρασκευή, 1 Ιουλίου 2011

Host your own e-mail server

 

E-mail is more pervasive these days than the business letter was just a couple of decades ago. Having a reliable e-mail server is crucial to most businesses. However, many companies—particularly smaller ones—have not taken the next step to host their own mail servers. Some rely on their local ISP to provide e-mail services, while others turn to Hotmail, Yahoo, or other global mail service providers. Hosting your own mail server offers some nice advantages, whether you need to support hundreds of users or just want to put in your own mail server in a small office. In this Daily Drill Down, I'll take you through the ins and outs of setting up your own mail server.

An e-mail server to call your own
Most national and local Internet service providers don’t offer a lot of features when it comes to their mail systems. The majority of them give you the ability to filter your messages so you can try to block all those annoying messages for herbal diet plans, debt consolidation, and hot stocks, not to mention all those unsolicited messages you wouldn’t want your dear old granny to see. But that’s about where the level of service ends. If you want features such as out-of-office replies, automatic responses, unlimited mailboxes, and mail forwarding, you need to take matters into your own hands and put in your own mail server.

You might think that putting in your own mail server means a big outlay in new equipment, expensive software, and time to manage it all. As long as you have an always-on, broadband Internet connection, however, it can be a snap. Because many of the mail server applications run on Windows 9x and other nonserver operating systems, you may not even need to change your existing systems. Even if you don’t have a dedicated Internet connection, you can still install a mail server that dials your ISP to send and receive messages.

What you do need, however, is an understanding of how e-mail messages get routed on the Internet, how to make those messages come and go through your server, what features to look for in a mail server, and then how to put it all together into a working package. Before I get into the nuts and bolts topics, let’s take a look at what you can expect from your own mail server.

What will you gain or lose?
One of the main things you’ll gain from setting up your own mail server is complete control over how many mailboxes you can have, how those mailboxes are set up, and how they work. Are you running into size limitations on your existing mail service? Does your current mailbox keep filling up or rejecting your messages because they are too large? No problem! When you own the mail server, you can do whatever you want. Go right ahead and send that 20 MB attachment to the remote office.

That brings up another important advantage that your own mail server can provide. You can extend the benefits to others, hosting accounts for other branches or even partners. That’s particularly nice if you’ve succeeded in securing a domain name for your company. The downside comes if your remote sites and business partners start to rely a little too much on their mail accounts. If your Internet connection goes down for a few days for reasons beyond your control, or your server suddenly develops a bad case of virus-of-the-week, you don’t want people calling at 2 A.M. to complain about it. I’ve been in the 24/7 support business and hated it. You will, too, if you get in that position. If you open your server to others, make sure they understand that they get what they pay for and should have a backup option, such as Hotmail or Yahoo. You should have a backup for your own e-mail account as well.

Autoresponders are another handy feature offered by many mail servers, and they're much like out-of-office replies. For example, maybe you have a document you want people to be able to obtain simply by sending a message to a specific account. A customer can send a message to fudge@yourdomain.whatever and get back a reply with your favorite fudge recipe. Businesses often use autoresponders to distribute information about products and services. Whether you manage services for a commercial venture or run a small home business, autoresponders might add a new way for you to interact with your customers.

Many mail servers offer features that make it easier to distribute mail to groups of people. While you can create distribution lists with any e-mail client, creating groups at the server lets anyone send mail to that group through a single e-mail address. Some mail servers give you the ability to send messages to group members in round-robin fashion. This means that each new message gets sent to a different person in the group. This is a great way to distribute messages evenly across the group, and it is typically used to distribute sales or support requests.

Keeping out spam is another potential benefit to hosting your own mail server. While you can create rules in your e-mail client to delete messages from specific senders, keeping out spam for several mail accounts can be a headache, particularly if your current service doesn’t give you any spam-blocking features. With antispamming built into the server, you can block mail from domains or specific senders for all accounts.

Many mail servers also provide built-in virus scanning or can use add-ins to scan messages coming and going through the server. You might use this in conjunction with client virus-scanning software to add another layer of security for your home network.

Laying the groundwork
To set up your own e-mail server and keep it working, you need some understanding of how e-mail gets routed across the Internet. Simple Mail Transport Protocol (SMTP) is the glue that binds Internet messaging. Mail servers use this protocol to communicate with one another, and e-mail clients use it to send messages. For example, let’s say I send a message to Uncle Ned asking for a copy of his pickled onion recipe. My mail program (let’s assume Outlook Express) connects to the mail server for my mail account using SMTP commands.

Through these commands, my message gets placed in the server’s outgoing mail queue. The server then looks at the address for the message to determine the destination. It queries the DNS to find the IP address of the mail server that serves that destination domain. My server then uses SMTP to communicate with the other server to deliver the message. If a network or server problem prevents the two servers from transferring the message, the message remains in the sending server’s outgoing queue for a specific period of time (the default is usually four days). The server periodically tries to resend the message, and if it can’t do so by the time the specified expiration period occurs, it returns the message to the sender with a nondelivery receipt (NDR).

When it comes time for Uncle Ned to retrieve the message, he has a handful of options. The most common is the POP3 protocol. When you connect to a mailbox on an ISP’s mail server, the mail program uses POP3 to retrieve the message. With POP3, messages are downloaded to your local computer, but you can optionally leave a copy of the messages on the server. This lets you also retrieve the messages from another computer, if needed.

IMAP is another protocol supported by many mail servers. With IMAP, the messages remain on the server and you access them live. You can read and delete messages from the server as well as create new ones. However, new messages are sent using SMTP rather than IMAP. IMAP is a good option when you need to access mail from more than one computer, because the mail is always available on the server instead of being downloaded to your computer—you don't have to worry about synchronizing mail stores on different computers. However, it does require a mail client, such as Outlook Express, Outlook, or Eudora, that supports IMAP accounts.

Some mail servers also support HTTP, the same protocol used to serve up Web pages. HTTP support lets you send and receive e-mail through your Web browser. Yahoo and Hotmail are two examples of services that provide HTTP-based e-mail, and Outlook Web Access (OWA) under Exchange Server also offers this capability. The main advantage to using HTTP is that you don’t need a dedicated e-mail client program but can instead rely on your Web browser to send and receive e-mail. This makes it easy to work with your messages from any computer.

Choosing the right software
I owned and operated an ISP for several years and used Microsoft Exchange Server to provide e-mail to our customers. As you may have guessed, I instinctively recommend Exchange Server for new e-mail servers. However, Exchange Server lists for just under $700 without any client licenses and just under $1,300 with five licenses, so that puts it out of range of most small businesses.

If Exchange Server seems like too much horsepower or too much money, there are lots of other good commercial, shareware, and even freeware mail server programs that range in price from free to a few hundred dollars. A search of popular download sites such as CNET Shareware.com, Tucows, and others will turn up a couple dozen e-mail server programs.

When you’re looking for a mail server to use in your business or home office, start by weeding out the ones that won’t run on your operating system. In most cases, programs designed to run on Windows NT or Windows 2000 will also run on Windows XP, but check with the vendor to be sure. Also, most of the mail servers for Windows NT run on both Workstation and Server, while most of the ones written for Windows 2000 run on both Professional and Server.

Next, decide which protocols and features you want from your mail server. POP3 and SMTP support are a given, but if you want HTTP support, your choices will be more limited since that’s one feature that many mail servers don’t have. Still, there are servers available that support HTTP, and they don't cost an arm and a leg. The convenience of being able to send and receive messages through a browser might offset the additional cost for a server that supports HTTP or an HTTP add-on.

Once you’ve narrowed your selection based on protocols, you can start looking at the other features you need. Some mail servers function mainly as mail gateways to your existing ISP mail server and don’t act as stand-alone mail servers for direct e-mail delivery from the Internet. Others offer both capabilities, functioning as a stand-alone mail server while also retrieving your mail from other mail services.

Next, look at special account features such as support for autoresponders, mail groups, the ability to function as a mailing list server, spam filtering, virus scanning, and any other advanced features you’d like to have.

Putting it all together
One aspect I haven’t discussed yet is how you hook up your server to the Internet. You should become familiar with the process before you buy software and get too far into making any system changes.

First, you’ll need your own domain if you want to receive messages directly to your server. You can register your domain at Network Solutions, Register.com, Go Daddy, WebSite.ws and through other domain providers. When you register a domain, you need to provide the IP address and host name of at least one DNS server for your domain, although most registration services require two DNS servers. If you run Windows NT Server or Windows 2000 Server, you can use the DNS service included in those platforms to host your own DNS records. Otherwise, you can use a third-party DNS server application.

Next, you need to create or have your registrar create a host record in the DNS zone for your domain. The host record associates a host name with an IP address. For example, the host name of my mail server is mail.boyce.us. In addition to the host record, you also need an MX record. This mail exchanger record tells other mail servers what address to use to deliver mail to your domain. Again, you need to create the MX record on your own DNS server or have your registrar create it on its servers, depending on where your DNS service resides. Both records need to point to your public IP address.

Now it’s time to hook up your server. If yours is like most networks with a broadband connection, you have a small number of public IP addresses (perhaps only one), and all of your computers use private IP addresses. The MX record must reference the public IP address because that’s the only one the outside world can see. So, if your DSL router or cable modem is assigned the one public IP address, it needs to forward the incoming SMTP traffic to the private IP of your mail server.

Check the documentation for the unit and see if it supports one-to-one Network Address Translation (NAT). Many cable/DSL routers let you translate specific ports, so you would configure the unit to pass port 25 (SMTP) from the public IP to the private IP of your mail server. If you’re using your own DNS server, you’ll also need to translate port 53 to move DNS traffic to the private IP address of your DNS server (probably the same computer that’s handling mail). If anyone, including you, needs to be able to retrieve messages from the server outside of your network (such as from the Internet), you also need to translate port 110 (POP3) from the public IP to the private IP of the mail server.

If your cable/DSL router doesn’t support NAT, you’ll have to either replace it or obtain a second public IP address from your ISP. Then, set up the server with that IP address. How you hook the server into the network depends on the type of equipment you use, so check with your ISP if you aren’t sure.

The last step is to install the mail server software and start setting up and configuring accounts. You’ll also need to set up DNS and get that working if you'll be providing your own DNS services. Then, you can start e-mailing to your heart’s content.
Read more...