HAProxy is an open source, it's a very fast and reliable solution for Load balancing, high availability and proxying for TCP and HTTP. This is suitable for high traffic websites and the most visited ones. 

This post describes how to install the HAProxy and simple TCP configuration with maximum connections. We'll be using Ubuntu 14.04.3 LTS as our base operating system and install haproxy-1.6 version. Before starting to build that HAProxy we need to make sure that the dependencies are installed in the system.

Install Dependencies:
 

# sudo aptitude update

# sudo aptitude install build-essential make g++ libssl-dev

Next, select your HAPorxy version based on our operating system, because of it's provides various versions to use in Debian and Ubuntu. 

Open this URL to view different version and choose package suitably.

http://haproxy.debian.net/

You need to enable a dedicated PPA with the following command:
 
# apt-get install software-properties-common

# add-apt-repository ppa:vbernat/haproxy-1.6

Then, execute the following commands to update and install haproxy-1.6 ,
 
# apt-get update

# apt-get install haproxy

To find the version,
 
# haproxy -v


HA-Proxy version 1.6.4 2016/03/13

Copyright 2000-2016 Willy Tarreau


The below commands are start, stop, restart and status of the HAProxy service,
 
# service haproxy start

# service haproxy stop

# service haproxy restart

# service haproxy status

Configuration :

Basic configuration for TCP connections frontend and backend,

TCP connection port number is 1900 (frontend and backend).

maxconn 2000000
mode tcp
balance roundrobin
192.168.1.100:1900
192.168.1.101:1900
192.168.1.102:1900

Open your HAProxy configuration file, remove the existing lines and add all lines into it or check and append the below lines,
 
#  vim  /etc/haproxy/haproxy.cfg



global

        log /dev/log    local0 debug

        log /dev/log    local2 info

        log /dev/log    local1 notice

        chroot /var/lib/haproxy

        stats socket /run/haproxy/admin.sock mode 660 level admin

        stats timeout 30s

        user haproxy

        group haproxy

        daemon

        maxconn 2000000



        # Default ciphers to use on SSL-enabled listening sockets.

        # For more information, see ciphers(1SSL). This list is from:

        #  https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/

        ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS

        ssl-default-bind-options no-sslv3



##### ~HAPROXY FRENTEND~ ######

frontend haproxymaster

        bind *:1900

        mode tcp

        maxconn 2000000

        tcp-request inspect-delay 3s

        timeout client          1m

        #Define Backend

        default_backend thelinuxfaq



##### ~HAPROXY FRENTEND~ ######

backend thelinuxfaq

        mode tcp

        balance roundrobin

        stick store-request src

        server your-hostname 192.168.1.100:1900 check

        server your-hostname 192.168.1.101:1900 check

        server your-hostname 192.168.1.102:1900 check

        timeout connect        10s

        timeout server         1m





defaults

log global

log 127.0.0.1:514 local0         # only send important events

log 127.0.0.1:514 local0 notice  # same but the limit output level

log ${LOCAL_SYSLOG}:514 local0 notice   # send to a local server



        mode    tcp

        option tcplog

        timeout connect 5000

        timeout client  50000

        timeout server  50000

        errorfile 400 /etc/haproxy/errors/400.http

        errorfile 403 /etc/haproxy/errors/403.http

        errorfile 408 /etc/haproxy/errors/408.http

        errorfile 500 /etc/haproxy/errors/500.http

        errorfile 502 /etc/haproxy/errors/502.http

        errorfile 503 /etc/haproxy/errors/503.http

        errorfile 504 /etc/haproxy/errors/504.http



#view on UI (Webbrowser)



listen  stats

        bind            :1936

        mode            http

        log             global



        maxconn 10

        stats enable

        stats hide-version

        stats refresh 30s

        stats show-node

        stats auth username:password

        stats uri  /haproxy?stats


Finally, save and restart the HAProxy service.

If you want to view the HAProxy Statistics Report on the web browser. Assume that, If your server IP address is 192.168.1.200,

URL : http://192.168.1.200:1936/haproxy?stats

User Name : username
Password  : password