How to get all your mail going out of one IP address with POSTFIX

If you have multiple IPs (ETH0,ETH0:0, etc) running on a server with Postfix, chances are you are going to run into the problem of Postfix not using the mail IP that has the matching MX record to send mail.

When this happens most of the mail servers will label your mail as SPAM and/or reject it.

You can force Postfix to use the main servers IP address by adding the following lines to your /etc/postfix/main.cf:
smtp_bind_address = 1.1.1.1

*You would replace 1.1.1.1 with the main IP of your own server.
Restart Postfix with /etc/init.d/postfix restart

This might cause your mail to backup on the server if your have other services  that might need a configuration tweak to continue working correctly, check your mail queue with this:
postqueue -p

If you see mail backing up in that queue for failed connections to 127.0.0.1, then you might have to start making some tweaks. If not, then you should be OK.


If you have AMAVIS running on the server then you might need to make this tweak for AMAVIS to properly work. Create the file /etc/amavis/conf.d/60-custom. Add the following line:
@inet_acl = qw( 127.0.0.1 [::1] 1.1.1.1 );

Restart AMAVIS with /etc/init.d/amavis restart

Now check the Postfix queue with postqueue -p again. If there is any mail still there try flushing it out with postqueue -f. The recheck it after a couple of seconds with postqueue -p again. It should be all gone now.

Keeping the Botters, China and miscreants away.

On a daily basis I troll my FAIL2BAN mail folder to see who is "ding-dong diving", "n*gger knocking" or what-ever the term of the day is.

My Fail2Ban is setup to send me mail every-time it bans an IP. Repeat offenders get the firewall treatment. I run a filter to move the to a separate folder of the same name.

I end up using IP tables to block the repeat offenders. They are just wasting your precious resources.

This is what I use so far:

iptables -I INPUT -m iprange --src-range 107.160.0.0-107.160.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 111.72.0.0-111.79.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 114.96.0.0-114.103.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 120.192.0.0-120.255.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 121.254.128.0-121.254.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 163.177.0.0-163.177.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 183.0.0.0-183.63.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 185.60.229.0-185.60.229.255 -j DROP
iptables -I INPUT -m iprange --src-range 187.1.16.0-187.1.31.255 -j DROP
iptables -I INPUT -m iprange --src-range 189.213.72.1-189.213.79.254 -j DROP
iptables -I INPUT -m iprange --src-range 194.63.142.0-194.63.142.255 -j DROP
iptables -I INPUT -m iprange --src-range 219.234.174.0-219.234.174.191 -j DROP
iptables -I INPUT -m iprange --src-range 222.184.0.0-222.191.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 27.255.64.0-27.255.95.255 -j DROP
iptables -I INPUT -m iprange --src-range 59.99.0.0-59.99.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 60.166.0.0-60.175.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 61.176.0.0-61.176.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 80.82.64.0-80.82.79.255 -j DROP
iptables -I INPUT -m iprange --src-range 81.17.88.0-81.17.95.255 -j DROP
iptables -I INPUT -m iprange --src-range 89.248.174.0-89.248.174.127 -j DROP
iptables -I INPUT -m iprange --src-range 93.174.88.0-93.174.95.255 -j DROP
iptables -I INPUT -m iprange --src-range 192.99.0.0-192.99.255.255 -j DROP
iptables -I INPUT -m iprange --src-range 122.228.228.0-122.228.228.15 -j DROP
This has reduced my Fail2Ban folder from 45+ emails a day to 10 at most.

I still get the occasional flurry, but you firewall the IP range and your done.

I can handle sending out 10 abuse mail forwards a day.

Disabling root ssh is very good Idea

Found a few good sites with too much information: They all boil down to giving SUDO access to one of your other accounts and disabling ssh access for the root account. Your can still login as root through your datacenters provisioned KVM since it emulates a local keyboard and video display. In case you ever get locked out or your IP banned for some reason.

As a failsafe, you might consider putting the public IP of a trusted source in the
/etc/hosts.allow file in case you get locked out accidentally. That why you know that all you need to do is go to that place to restore access to your account. It could be your office's public IP, or campus university public IP, or just another server you have control over.

Once you have SUDO access on another account:
Just edit /etc/ssh/sshd_config and make sure this line PermitRootLogin no , reads as so.

Upgraded most of my boxes to Debian 7 Wheezy and ISPCONFIG

For the most part I'm happy to be on Debian 7 with ISPCONFIG, as DTC was taking forever to update their code to make it Debian 7 compatible; and my clients were installing software requiring the latest PHP and MYSQL. So I really didn't have much of a choice in the matter.

I like and dis-like a few things about ISPCONFIG.

LIKES:

• Offers and Handles multiservers very well.
• easy to install guides
• well documented
• many howto guides for just about every option
• cheap billing module

DISLIKES:

• creating a website or sub-domains does not automatically create a DNS entries/mail domains/etc, you have to expect your customers to know what they are doing. It's not as user-friendly in that aspect. It would be nice if it offered a dummy mode or wizards for users. In this aspect DTC was nice to do everything for you when you added a domain. Then you just had to do any customizations required, but the basics where created for you.

Hacked by FreshJoomlaTemplates.com

Beware with some of the free templates from freshjoomlatemplates.com as they have scripts embedded in them that can take over your site and use it to send spam.

I already had a bad experience that cost me days of downtime and having to move my server to a different colo.

The up-side is that my new service has never been interrupted by DDOS attacks so far.

Limiting recursive lookups in Bind

Limiting recursive lookups in Bind is a good idea for several reasons:

1. Why give free DNS service to the entire internet.
2. A source of denial of service flood attack.
3. Increases traffic, which may increase costs.
4. Increases CPU usage.

In /etc/bind/named.conf.options:
 acl "trusted" {
     111.222.333.444/55;
        127.0.0.1;
     localhost;
     localnets;
 };

options {
        directory "/var/cache/bind";
        auth-nxdomain no;    # conform to RFC1035
        additional-from-auth no;
        additional-from-cache no;
        allow-query { any; };
        allow-recursion { trusted; };
        allow-query-cache { trusted; };

};

Binding postfix to use a specific ip address.

Now-a-days with SPF records and such, it's always a good idea to limit postfix to use the ip address specified in the spf record to prevent your mail from being marked as spam. This is only necessary if your server has more that one ip bound to it. 

In /etc/postfix/main.cf add:
smtp_bind_address = 111.222.333.444

This will limit your postfix server to using the ip specified.