A proxy server is a server application or appliance that acts as an intermediary for requests from clients seeking resources from servers that provide those resources

source Wikipedia

We have to mainly do some configurations to work with proxychains on linux:

nano /etc/proxychains.conf

When working with proxies we have different protocols at our disposal:

• HTTP: HTTP only and not very secure
• SOCKS4: doesn’t support IPv6 nor UDP
• SOCKS5: the most secure option

Furthermore, we can use different policies:

• dynamic_chain: proxies from a list and skips the ones that are unavailable
• strict_chain: proxies from a list but all have to be online or it brakes
• random_chain: changes the proxy for each package - very slow.

As we can see, dynamic_chain is what we want as its the most robust option. So comment the strict_chain and uncomment the dynamic_chain from the config file.

Among the configurations, we have to make sure the proxy_dns configuration is uncommented as this prevents the DNS from leaking. When we access the web our local ISP accesses a local DNS server to find the IP of the site we are requesting which will expose the DNS server information. While they can’t find our IP address directly it is possible to figure out our location through our local DNS server.

Now we can start adding proxies to our list inside the config:

# format
# TYPE  HOST  PORT  USER  PASSWORD
socks5  127.0.0.1  9050

We can now see the current status of tor in the terminal and check our connection:

# check status
service tor status

# start tor
service tor start

# check connection
proxychains firefox www.ecosia.org

# use proxychains for anything (nmap, firefox, etc.)
proxychains programName

We are ready to add proxies to our proxychain now. A simple search for free proxies will give us a lot of sites that host large lists of proxies which we can copy/paste into our configuration file at the bottom following the specified format. Its important to keep in mind that the more proxies we add to our proxychains the slower our connection will be. A good number is between 2-5.