How to quickly become firewall expert with UFW !

Uncomplicated Firewall (UFW) is a helper tool which allows you to quickly setup iptables firewall in any Ubuntu server. It is installed by default and it allows you to secure your server at no time!

Basic UFW

Basic UFW: Check Status
You can check UFW by running this command. The verbose argument prints additional information such as UFW profiles, logging settings.

The ‘numbered’ argument prints the list of rules with line number. I’ll explain later on the use of this feature.

sudo ufw status
sudo ufw status verbose
sudo ufw status  numbered

Basic UFW: Enable and Disable Firewall
You can easily enable and disable firewall by specifying ‘disable’ and ‘enable’ argument.

Warning : Please do not enable UFW if you’re connecting using SSH connection to your Ubuntu box, you might be disconnected.

sudo ufw disable
sudo ufw enable

Basic UFW: Setting up default rule and Enabling SSH
A lot of you might be connecting to Ubuntu box using SSH connections, so the first step is to setup a default rule and enabling SSH connection.

Deny incoming connection

sudo ufw default deny incoming

Allow incoming SSH connection

sudo ufw allow ssh

Alternatively you can write:

sudo ufw allow 22/tcp

Finally, enable firewall

sudo ufw enable

You can check the firewall rules by running

sudo ufw status

Basic UFW: Enabling other service: HTTP, HTTPS

Enabling web server port and https is as easy as running

sudo ufw allow http
sudo ufw allow https

Basic UFW: Deleting rule
You can delete UFW rule by running

sudo ufw delete allow https

or by specifying its port and protocol

sudo ufw delete allow 443/tcp

Additionally you could also delete rule using its number by running “ufw status numbered” first

sudo ufw status numbered
ufw status numbered
Status: active

     To                         Action      From
     --                         ------      ----
[ 1] 22                         ALLOW IN    Anywhere
[ 2] 22/tcp                     ALLOW IN    Anywhere
[ 3] 443                        ALLOW IN    Anywhere
[ 4] 22 (v6)                    ALLOW IN    Anywhere (v6)
[ 5] 22/tcp (v6)                ALLOW IN    Anywhere (v6)
[ 6] 443 (v6)                   ALLOW IN    Anywhere (v6)

Then pick a firewall rule based on its number to delete, I picked number 3 and 6, because I want to delete https rule

sudo ufw delete 3
sudo ufw delete 6

UFW will print a confirmation prompt and you can continue deleting the firewall rules

/home/mypapit# ufw delete 6
Deleting:
 allow 443
Proceed with operation (y|n)? y   
Rule deleted (v6)

/home/mypapit# ufw delete 3
Deleting:
 allow 443
Proceed with operation (y|n)? y
Rule deleted

Intermediate UFW

Intermediate UFW: Deny access from ip address or ip block
You can prevent certain ip address or ip blocks / subnets from reaching your server by running:

sudo ufw deny from 172.18.44.12

Deny an ip address subnet

sudo ufw deny from 172.18.44.0/24

Deny an ip address subnet, example #2

sudo ufw deny from 172.16.0.0/16

Intermediate UFW: Allow services to be connected from certain ip address or subnet
In this case, I will only allow certain ip address to connect to my SSH port.

First we delete the old – “allow all” SSH rule

sudo ufw disable
sudo ufw delete allow ssh

Then we add ip address to be allowed to connect to SSH port

sudo ufw allow from 192.168.20.40 to any port ssh

Alternatively, you could also specify port number and protocol

sudo ufw allow from 192.168.20.40 to any port 22 proto tcp

Only allow SSH connections from certain subnets

sudo ufw allow from 192.168.20.0/24 to any port 22 proto tcp

Note: Adding firewall rules to only allow SSH connection from certain subnets would increase the server security, further reducing brute-force attack.

Further Reading: Ubuntu Server Administrator Reference

Python code: List most popular URL from Apache/NGINX ‘access.log’ file

Found a great Python code snippet for listing the most popular URL from Apache / NGINX ‘access.log’ file. Very practical!

import collections

logfile = open("access.log", "r")

clean_log=[]

for line in logfile:
    try:
        # copy the URLS to an empty list.
        # We get the part between GET and HTTP
        clean_log.append(line[line.index("GET")+4:line.index("HTTP")])
    except:
        pass

counter = collections.Counter(clean_log)

# get the Top 50 most popular URLs
for count in counter.most_common(50):
    print(str(count[1]) + "\t" + str(count[0]))

logfile.close()

The code is very handy if you want to find out the most popular URL or pages in your website, crucial information for optimization, IMHO.

How to install NGINX with PageSpeed module in Ubuntu LTS / Debian

UPDATE: You can now install NGINX with PageSpeed in Ubuntu LTS with deb package: https://blog.mypapit.net/2015/08/install-nginx-with-pagespeed-using-deb-for-ubuntu-lts-amd64.html

INSTALLING NGINX USING UBUNTU APT-GET SOURCE
PageSpeed modules are open source modules developed by Google Inc that can perform website optimization to ensure faster site delivery, automatically.

PageSpeed module is not included in NGINX installation in Ubuntu or Debian. So you need to recompile NGINX together with PageSpeed module, to enable its functionality.

You can install NGINX 1.8.0 with PageSpeed for Ubuntu 14.04 LTS here, using dpkg:
or you can compile it from source code using apt-get.

There are several steps to this method, first you need to get the latest nginx stable (or mainline) from PPA (optional)

#this step is optional, only if you want to get the latest Ubuntu version of nginx

sudo apt-get -y install software-properties-common

sudo -s

nginx=stable # use nginx=development for latest development version
add-apt-repository ppa:nginx/$nginx

apt-get update 

apt-get -y upgrade

Then, you’ve to install dpkg-dev, unzip utility and nginx source from apt repository

apt-get -y install dpkg-dev unzip

apt-get install nginx

apt-get source nginx

After that, you need to download PageSpeed module, this instruction is adapted from

https://developers.google.com/speed/pagespeed/module/build_ngx_pagespeed_from_source

**note replace ${NGINX_VERSION} with the version of NGINX available from apt-get, in my case – its “1.8.0”

cd
export NPS_VERSION=1.9.32.4
export NGINX_VERSION=1.8.0

wget -c https://github.com/pagespeed/ngx_pagespeed/archive/release-${NPS_VERSION}-beta.zip

unzip release-${NPS_VERSION}-beta.zip

cd ngx_pagespeed-release-${NPS_VERSION}-beta/

wget -c https://dl.google.com/dl/page-speed/psol/${NPS_VERSION}.tar.gz

tar -xzvf ${NPS_VERSION}.tar.gz

cd nginx-${NGINX_VERSION}

Install all build dependencies (your configuration may varies, but i keep it within default Ubuntu configuration.

apt-get -y install libpcre3-dev libssl-dev libxslt1-dev libgd-dev libgeoip-dev geoip-bin geoip-database libpam0g-dev zlib1g-dev memcached

Then configure nginx, remember to replace ${NGINX_VERSION} with your current version of NGINX. In my case, its “1.8.0”

cd nginx-${NGINX_VERSION}

./configure  --with-cc-opt='-g -O2 -fPIE -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-Bsymbolic-functions -fPIE -pie -Wl,-z,relro -Wl,-z,now' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit --with-ipv6 --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_addition_module --with-http_dav_module --with-http_geoip_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module --with-http_spdy_module --with-http_sub_module --with-http_xslt_module --with-mail --with-mail_ssl_module --add-module=debian/modules/nginx-auth-pam --add-module=debian/modules/nginx-dav-ext-module --add-module=debian/modules/nginx-echo --add-module=debian/modules/nginx-upstream-fair --add-module=debian/modules/ngx_http_substitutions_filter_module --sbin-path=/usr/local/sbin --add-module=$HOME/ngx_pagespeed-release-${NPS_VERSION}-beta

After that, run make and make install

make

make install

The newly compiled nginx will be installed in “/usr/local/bin” without overwriting the original binary file.

Create nginx-pagespeed /etc/init.d file

Optionally you may duplicate nginx in init.d, and rename it to nginx-pagespeed, and stop the original nginx server

cp /etc/init.d/nginx /etc/init.d/nginx-pagespeed

sed -i 's|/usr/sbin/nginx|/usr/local/sbin/nginx|g' /etc/init.d/nginx-pagespeed

service nginx stop

You may also enable basic PageSpeed config in /etc/nginx/conf.d/

nano /etc/nginx/conf.d/pagespeed.conf

And add these basic PageSpeed config

#file /etc/nginx/conf.d/pagespeed.conf
        pagespeed on;
        pagespeed FetchWithGzip on;

        pagespeed FileCachePath /run/shm/pagespeed_cache;
        pagespeed RewriteLevel CoreFilters;

Save the file, and test nginx config, after that, start nginx-pagespeed service.

/usr/local/sbin/nginx -t

service nginx-pagespeed start

**Note: This instruction has been tested under Ubuntu 14.04 LTS with nginx 1.8.0 from ppa:nginx/stable respository. The LTS is chosen because it has much longer support for server, and nginx 1.8.0 supports both spdy 3.1 and latest PageSpeed.

***Please share any thoughts or opinion or suggested correction if this guide didn’t work for you. Thanks!!

Recommended Reading

Connecting blog with IFTTT !

I’ve managed to connect this blog with IFTTT! However due to certain security restriction that I’ve enforced on this blog to curb spammers and unauthorized access (aka crackers), I’ve decided against connecting my blog directly through XMLRPC endpoint. So I’ve use RSS/ATOM feeds instead.

IFTTT is a wonderful service which allows you to connect various services to perform automated task on another web service. Very convenient for busy people!

ifttt

*IFTTT stands for “If this, then that” which is a programming metaphor in basic automatic decision making or branching.