How2 - Shorewall Firewall - Deb5 / Ubuntu 9

allofus · Mar 16, 2010

This is my basic how2 for shorewall firewall on the VPS for deb5 / ubuntu 9
http://www.shorewall.net

prepare your VPS;

Code:

apt-get update
apt-get upgrade -y

Install shorewall;

Code:

apt-get install shorewall

/etc/shorewall
/etc/default/shorewall
/usr/share/shorewall
/usr/share/shorewall-shell
There are also some examples and manuals in /usr/share/doc/shorewall *

shorewall is now installed well done, go get a beer and chill.
Thats it.... joke, if only.

Now you need to setup the interfaces, zones, policy rules, blacklist

Code:

cd /etc/shorewall
dir

output;

Code:

Makefile  shorewall.conf

shorewall.conf is your config file and there is only really 1 edit that you need to make to get started.

Code:

vi /etc/shorewall/shorewall.conf

find

Code:

DISABLE_IPV6=

make sure it says

Code:

DISABLE_IPV6=No

This disables IPV6 support seems backwards but it does.

There is a redundant file that needs removing to stop some errors being notified later, but lets rename and move it just incase...

Code:

cp /etc/modprobe.conf /etc/modprobe.d/was-modprobe.conf
rm /etc/modprobe.conf

Now to setup the firewall

interface; /etc/shorewall/interface
First we need to find the name of our interface

Code:

ip route ls

output;

Code:

192.0.2.1 dev venet0  scope link
default via 192.0.2.1 dev venet0

The name of the external interface is written directly after the device, dev and in my case is 'venet0'

Now we have our dev name we can create the interface file

Code:

vi /etc/shorewall/interface

and add the following;

Code:

###############################################################################
#ZONE    INTERFACE    BROADCAST          OPTIONS
*net     **venet0          ***detect/99.198.122.55,99.198.122.56       ****blacklist
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE

REMOVE STARS.... * ** *** ****
*net
this is the name we are going to give to the interface for future reference in rules and zones
net could have been joan, matthew, peter, ihateu it is just a name but net makes good sense

**venet0 is the dev name and needs to be accurate following 'ip route ls'

***detect/99.198.122.55,99.198.122.56
here you have 2 options;
detect - will detect your external ip

or

comma (,) seperated ip list will be a list of your ip's
use just 1 or the other
detect/ bad
/12.24.36.48 - bad

I use
99.198.122.55,99.198.122.56
99.198.122.55 will also work but obviously only for this IP

****blacklist - another comma seperated list of features to apply to this interface. In this tutorial I shall only focus on getting an ALLOW/macronames + the mentioned blacklist

here is is again without the stars;

Code:

###############################################################################
#ZONE    INTERFACE    BROADCAST          OPTIONS
net     venet0          99.198.122.55,99.198.122.56       blacklist
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE

zones; /etc/shorewall/zones

Code:

vi /etc/shorewall/zones

and add the following

Code:

###############################################################################
#ZONE    TYPE        OPTIONS        IN            OUT
fw    firewall
net    ipv4
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE

If you used joan, matthew, peter, ihateu instead of net change it in your file but that is the ONLY change you can make.

fw is coded into the installed scripts and is non-negotiable.

policy; /etc/shorewall/policy

Code:

vi /etc/shorewall/policy

and add the following

Code:

###############################################################################
#SOURCE        DEST        POLICY        LOG        LIMIT:BURST
#                        LEVEL
$FW        net        ACCEPT        info
net        $FW        ACCEPT        info
net        all        DROP        info
all        all        REJECT      info
#LAST LINE -- DO NOT REMOVE

Again no chnage other than that 1 'net' name.
This is the default policy for the firewall and will always do this if there are no rules stating otherwise.

rules; /etc/shorewall/rules
vi /etc/shorewall/rules
and add the following

Code:

#######################################################################################################
#ACTION SOURCE          DEST     PROTO   DEST    SOURCE          ORIGINAL        RATE            USER/
#                                        PORT(S) PORT(S)         DEST            LIMIT           GROUP
#SECTION ESTABLISHED
#SECTION RELATED
SECTION NEW

ACCEPT    net    $FW    udp    1234
ACCEPT    net    $FW    tcp    2345

HTTP/ACCEPT     net   $FW
HTTPS/ACCEPT    net   $FW
IMAP/ACCEPT     net   $FW
IMAPS/ACCEPT    net   $FW
MySQL/ACCEPT    net   $FW
POP3/ACCEPT     net   $FW
POP3S/ACCEPT    net   $FW
SMTP/ACCEPT     net   $FW
SMTPS/ACCEPT    net   $FW
SSH/ACCEPT      net   $FW
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE

In the above example I have #manually opened 2 ports and then used macros to manage other protocals.

Macro's are available in the following folder
/usr/share/shorewall
remove the macro. from the name and add it to the list in your rules to use it.

If you wanted to change your default ssh port to 222 instead of 22 you could just edit the macro.SSH file to reflect this or you could add the port to the rules. edit macro. makes most sense to me.

blacklist; /etc/shorewall/blacklist

Code:

vi /etc/shorewall/blacklist

and add the following

Code:

12.24.36.48
15.30.46.60

Actually add whatever IP's you do not want to have access to your VPS in this file 1 per line and they will be denied access.

the last thing to do is enable the firewall to start on boot.

Code:

vi /etc/default/shorewall

find

Code:

startup=0

change it to

Code:

startup=1

start the firewall

Code:

shorewall start

is the firewall running?

Code:

shorewall status

apply those new rules / blacklist

Code:

shorewall refresh

apply any / all changes

Code:

shorewall restart

what is my firewall capable of right now?

Code:

shorewall show capabilities

Remember if you screw up to just edit the /etc/default/shorewall to 0 again and try again.

BTW if this all goes horribly wrong for you it is your fault for following the blind man...

How2 - Shorewall Firewall - Deb5 / Ubuntu 9

allofus

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