[2024-feb-29] Sad news: Eric Layton aka Nocturnal Slacker aka vtel57 passed away on Feb 26th, shortly after hospitalization. He was one of our Wiki's most prominent admins. He will be missed.
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howtos:network_services:postfix_dovecot_mysql:email_firewall [2015/02/15 19:20 (UTC)] – astrogeek | howtos:network_services:postfix_dovecot_mysql:email_firewall [2018/02/06 00:58 (UTC)] – Removed UFW syntax added by others - added policy lines astrogeek | ||
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- | ==== Firewall Rules For Virtual Mail Server ==== | + | ====== Firewall Rules For Virtual Mail Server |
- | <note important> | + | This page is supplemental to main article: [[howtos: |
A firewall is simply a set of kernel routing rules, iptables rules, that selectively block or allow network traffic into and out of your machine. A web facing email server must be secured by a suitable set of firewall rules or it will quickly be overwhelmed and compromised! | A firewall is simply a set of kernel routing rules, iptables rules, that selectively block or allow network traffic into and out of your machine. A web facing email server must be secured by a suitable set of firewall rules or it will quickly be overwhelmed and compromised! | ||
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If you already have a firewall in place for other services then you will need to add to it the rules necessary to support mail server traffic. If you do not have a firewall currently in place, then you may use the example below as a good starting point! | If you already have a firewall in place for other services then you will need to add to it the rules necessary to support mail server traffic. If you do not have a firewall currently in place, then you may use the example below as a good starting point! | ||
- | <note important> | + | <note important> |
You should first use iptables -L to check for pre-existing rules and merge those below into your existing firewall. | You should first use iptables -L to check for pre-existing rules and merge those below into your existing firewall. | ||
- | If you have no existing firewall and need to allow http and ssh, uncomment the liines | + | If you have no existing firewall and need to allow http and ssh, uncomment the lines for those also included here.</ |
Following is a minimal set of iptables rules to provide a firewall for your email server. | Following is a minimal set of iptables rules to provide a firewall for your email server. | ||
< | < | ||
+ | --policy INPUT DROP | ||
+ | --policy FORWARD DROP | ||
+ | --policy OUTPUT DROP | ||
+ | |||
-A INPUT -m state --state INVALID -j DROP | -A INPUT -m state --state INVALID -j DROP | ||
-A INPUT -m state --state ESTABLISHED, | -A INPUT -m state --state ESTABLISHED, | ||
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Ports 993 and 995 provide secure Imap and Pop3, respectively. These must be open in order for your virtual users to be able to send and receive email. | Ports 993 and 995 provide secure Imap and Pop3, respectively. These must be open in order for your virtual users to be able to send and receive email. | ||
- | You may enable | + | To install |
+ | There are many preferences for saving and loading firewall scripts. I generally use / | ||
< | < | ||
- | You may see all currently active rules like this... | + | |
+ | To see all currently active rules: | ||
< | < | ||
- | You may flush all current rules like this... | + | |
+ | To flush all current rules: | ||
< | < | ||
- | To load your firewall rules at each boot, add the following | + | To load your firewall rules at each boot, you will need to create a start script and save it to / |
+ | |||
+ | You may choose to create a more complete script with start and stop options, but the following simple script is sufficient to load your firewall rules at boot. | ||
< | < | ||
- | vi / | + | vi / |
# add the following lines # | # add the following lines # | ||
- | if [ -x / | + | if [ -e / |
iptables-restore </ | iptables-restore </ | ||
- | fi</ | + | fi |
+ | </ | ||
- | And make sure rc.local and the firewall | + | Make sure rc.firewall |
< | < | ||
- | chmod +x / | + | chmod +x / |
- | chmod +x /etc/firewall.rules | + | |
</ | </ | ||
- | Load your firewall rules and make sure they are as you expect them to be before continuing. | + | Load your firewall rules and make sure they are as you expect them to be before continuing. |
< | < | ||
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[[howtos: | [[howtos: | ||
+ | ====== Sources ====== | ||
+ | * Originally written by [[wiki: | ||
{{tag> | {{tag> |