Tito's Blog

Here are the steps to install rssh in the linux server :
Follow the below steps to install if your linux os is 32 bit :
Step 1: cd /usr/src
Step 2: wget http://dag.wieers.com/rpm/packages/rssh/rssh-2.3.2-1.2.el4.rf.i386.rpm
Step 3: rpm -ivh rssh-2.3.2-1.2.el4.rf.i386.rpm
If your linux os is 64 bit then follow these steps:
Step 1: cd /usr/src
Step 2: wget http://dag.wieers.com/rpm/packages/rssh/rssh-2.3.2-1.2.el5.rf.x86_64.rpm
Step 3: rpm -ivh rssh-2.3.2-1.2.el5.rf.x86_64.rpm

Installing Spamassassin

Installing Postfix Read my previous article - “Install and configure a Postfix mail server”

The installation of Spamassassin I am going to show you will be done completely in command line. So the very first step is to open up that terminal window and get ready to do a bit of typing (or copy/pasting).

The first step is to install Spamassassin. This is done with the command:

sudo apt-get install spamassassin

You will have to give your sudo password for the installation to continue. There may be some dependencies (this will be determined by what you already have installed on your machine). Allow apt to install the dependencies.

After Spamassassin is installed you are ready to begin the configuration. You will have to do some configuration in both Spamassassin and Postfix.

Configuring Spamassassin

The main configuration file for Spamassassin is /etc/spamassassin/local.cf. The first option you want to look for is the SPAM score option. Look for the line:

# required_score 5.0

Uncomment that line (remove the “#” character) and then change the numerical score to what you would prefer. As I mentioned earlier, a score of 3.5 is pretty safe.

Another great configuration option is to set up whitelist and blacklists within the configuration file. You would only want to do this for addresses that are often tagged incorrectly as SPAM. You can do this to whitelist single addresses or entire domains. For example:

whitelist_from mailme@titopanicker.net

would ensure that email from the address above was not marked as SPAM. Also:

whitelist_from *@titopanicker.net

would whitelist the entire domain somedomain.com. You can also have multiple entries per line separated by spaces like so:

whitelist_from jack@somedomain.com jennifer@somedomain.com olivia@somedomain.com

The same thing holds true for blacklisting, only the parameter is blacklist_from.

You will want to use caution if trying to add your own domain to a whitelist, because a spammer could spoof a local address and Spamassassin will allow it through.

Another configuration option is the report_safe option. Somewhere around the required_score line (this will depend upon the release you install) you will find the line:

# report_safe

This line will define how Spamassassin will handle any message marked as SPAM. If you set this line to:

report_safe 0

all incoming SPAM is modified by altering the header to mark said email as SPAM.

If you set this line to:

report_safe 1

all incoming messages tagged as SPAM will create a new report message and attach the original message as a message/rfc822 MIME (preserving the original message, but not easily opened).

If you set this line to:

report_safe 2

all incoming messages tagged as SPAM will be attached to a new report as plain text.

A message marked as SPAM will not be deleted. Instead a message marked as SPAM will be labeled as such and allowed through. This further prevents false positives and allows the user to define what to do with SPAM in their email client.

If you set that line to…

report_safe 1

…all messages marked as SPAM will be deleted. I find it best to set this to 0, so to avoid the loss of false positive email. If you set report_safe to 0 you will need to define how the header is rewritten so the message is properly labeled as SPAM. Look for this line:

# rewrite_header Subject *****SPAM*****

Uncomment this line (remove the “#” character) and then change the *****SPAM***** section to whatever you prefer it to be. Just make sure your users are aware of what this line is so they can handle it with their mail clients.

After you make this last change, save and close this file and restart the Spamassassin daemon with the command:

sudo /etc/init.d/spamassassin restart

Now you are ready to configure Postfix.

Configure Postfix

The configuration file you need to make changes to is /etc/postfix/master.cf. There are a few changes to make. The first change is to look for this line:

smtp inet n – - – - smtpd

You will need to change this line to:

smtp inet n – - – - smtpd -o content_filter=spamassassin

Now, take a look at the bottom of this configuration file and add the following:

spamassassin
unix – n n – - pipe
flags=R
user=spamd
argv=/usr/bin/spamc
-e /usr/sbin/sendmail
-oi -f ${sender} ${recipient}

That’s it. Now all you need to do is save that file and restart Postfix with the command:

sudo /etc/init.d/postfix restart

Installation

You will be shocked at how simple it is to install the Postfix mail server. All you have to do is follow these steps:

1) Open up a terminal window (or, if you are using a GUI-less server just log in).

2) Issue the command sudo apt-get install postfix.

That’s it! Of course, depending upon the current state of your distribution, the installation may or may not have to install some dependencies. But this will happen automatically for you. The installation will also automatically start the Postfix daemon for you. So as soon as installation is complete you can test to make sure you can connect to your Postfix server with the command:

telnet localhost 25

You should see something like this:

Trying 127.0.0.1…
Connected to www.mymail.com.
Escape character is ‘^]’.
220 localhost.localdomain ESMTP Postfix (Ubuntu)

Now you might want to first make sure you can also connect to your domain in the same way with the command:

telnet www.mymail.com 25

Of course you will use your own FDQN in the above command (instead of mymail.com). Hopefully you will see the same output you did when you used localhost. If not, you will have to check to make sure your domain is pointing to your server or that port 25 traffic can get to your server from your router, switch, or firewall. Those issues are beyond the scope of this article however.

Now it is time to start configuration.

Configuring Postfix

The Postfix mail server has one main configuration file /etc/postfix/main.cf. This is where you will do the bulk of your configurations. Open this file up in your favorite text editor and look for the following section:

myhostname =
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination =
relayhost =
mynetworks =
mailbox_command = procmail -a “$EXTENSION”
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all

This is the section of the configuration file you must focus on. And, believe it or not, there isn’t much to do. Below are the sections you need to configure:

myhostname: This is the hostname of your machine. But don’t put the full hostname. If your machine hostname is mail.mydomain.com you will only use mydomain.

mydestination: This parameter specifies what destinations this machine will deliver locally. The default is:

mydestination = $myhostname localhost.$mydomain localhost

You could also use something like what I have used in the past :

mydomain.com mydomain localhost.localdomain localhost

This call is up to you. Either way will work; but the latter line will help to avoid mailloops.

mynetworks: This line is a bit trickier. This entry will define authorized destinations that mail can be relayed from. You would think that adding your subnet here would work. Sometimes that is the case; sometimes not. You could go with a mynetworks entry that looks like:

mynetworks = 127.0.0.1/8

The above entry is a safe entry and defines local machines only.

You could also have an entry that looks like:

mynetworks = 127.0.0.1/8 192.168.100.1/24

The above entry would authorize local machines and your internal network addresses.

I have found, however, that the above entries will cause problems with relaying due to constantly changing dhcp addresses. Because of this I have used the following, specialized entry which will avoid this issue:

mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128

Now, if your mail server serves up mail to your entire domain, you will need to add another entry to that section above. That entry is:

mydomain = mydomain.com

Again, as in all configurations above, the mydomain.com will be substituted with your real domain.

Now, save that configuration file and restart your mail server with the command:

sudo /etc/init.d/postfix reload

Your mail server should be up and running.

Users

Since this is a Linux mail server, you will need to make sure you have a user name that corresponds with every email address you need. If your server has a GUI you can just use the GUI tool for this. If your server is a GUI-less server you can create users with the command:

sudo useradd -m USERNAME

Where USERNAME is the actual name of the user. The next step is to give the username a password with the command:

sudo passwd USERNAME

Again, where USERNAME is the actual username. You will be prompted to enter the new password twice.

Test Your Server

Go to an external source and send an email to one of your users on your new mail server. To find out if it worked you can log on as that user and use the Alpine command line email reader (you might have to install that first with the command sudo apt-get install alpine). If you do not see an email show up you will want to check the log file /var/log/mail.err which should give you some clues as to what is going wrong.