Concepts for Network Security
Tags: cybersecurity
Published: 2022-08-06 02:59:02

If you are working in Infrastructure as Services you must be aware of the below. There is no point working in Cloud computing without the below knowledge. People join in Cloud computing jobs as freshers, they have no clue about 𝗦𝗲𝗿𝘃𝗲𝗿- 𝗦𝘄𝗶𝘁𝗰𝗵 -𝗥𝗼𝘂𝘁𝗲𝗿 -𝗕𝗮𝗰𝗸𝘂𝗽 Servers- 𝗦𝘁𝗼𝗿𝗮𝗴𝗲 𝗯𝗼𝘅𝗲𝘀 (NAS/Software Defined) as days pass, they will be able to work on repetitive tasks alone and couldn't progress. Whenever you read, read it from scratch ask questions( Why, What, How)
𝗗𝗡𝗦 - Domain Name system. It maps your domain name with IP address. For example when you hit www.SANS.org it search the four servers available in the internet to find the Ip record.
The four servers are 
1. recursive resolvers, root nameservers, TLD nameservers, and authoritative nameservers.
𝗧𝗟𝗦 - Transport Layer Security, Majority of the browser nowadays use TLS. The data you send over internet is encrypted. Apparently, majority of the email and chat platforms aren't using TLS.
TLS use port 465. Follow this to enable TLS in your browser - https://lnkd.in/gytEmrpZ
𝗦𝗦𝗟 - Secure Socket Layer - SSL encrypts the link between a browser and Web Server. It ensures the data is private and secure. You can generate a SSL certificate from your server - https://lnkd.in/gkJ8Qc46
𝗛𝗧𝗧𝗣 - Hyper text transfer protocol - It operates at the TCP/IP level - The data transferred over this protocol is not private/not secure. Port number is 80
𝗛𝗧𝗧𝗣𝗦 - Hyper text transfer protocol secure - It uses http with SSL/TLS connection. The data transferred is secured/private. Port number is 443
𝗧𝗖𝗣/𝗜𝗣 𝗺𝗼𝗱𝗲𝗹 - It is responsible for transfer of messages between two devices. TCP breaks your messages into packets and sends them to the destination. The suite of protocols TCP/Ip use is listed below -
. Datalink layer .Internet .Transport Layer .Application Layer https://lnkd.in/gVKWyb4w
𝗧𝗧𝗟 - Time To Live.

DNS records:
𝗔 𝗿𝗲𝗰𝗼𝗿𝗱 - This is also called host name record as it stores the host name details along with its IP address (Ipv4)
It maps the domain name to the Ip address of the hosting server. We can configure multiple A records for one domain name.
to view your A record, use this 𝒄𝒐𝒎𝒎𝒂𝒏𝒅 - nslookup -debug brave.com   # (be it any site of your choice)
𝗔𝗔𝗔𝗔 𝗿𝗲𝗰𝗼𝗿𝗱 - This is exactly similar to A record wherein it stores your hostname along with your IPV6 address.
𝐂𝐍𝐚𝐦𝐞 𝐫𝐞𝐜𝐨𝐫𝐝 - This is known as Canonical Name record where the domain name points to a different domain name. 
Your request will reach the different domain name we specified earlier and its Ip address is returned.
Example - When you use a CName record and hit www.google.com the request redirects to www.yahoo.com (CNAME) and you are able to view the contents in www.yahoo.com
(Just an example here also applicable to offensive hack)
𝒄𝒐𝒎𝒎𝒂𝒏𝒅 in windows to check CName = nslookup -q=CNAME Shiva.com, In Linux = dig Shiva.com CNAME
𝗠𝗫 𝗿𝗲𝗰𝗼𝗿𝗱 - This is known as mail exchanger record; it directs your email to a mail server. Sender Mails without an MX record are considered spam and it gets rejected by mail server.
MX record points to A or AAAA record (Domain name). 
If your email domain name doesn't have a MX record you can send email, but you can't receive an email.
𝐡𝐭𝐭𝐩𝐬://𝐰𝐡𝐚𝐭𝐬𝐦𝐲𝐝𝐧𝐬.𝐦𝐞/ - this site gives the DNS record details for your domain name.
      To 𝒗𝒊𝒆𝒘 𝑴𝑿 𝒓𝒆𝒄𝒐𝒓𝒅 𝒐𝒇 𝒂 𝒅𝒐𝒎𝒂𝒊𝒏 in windows.
      In cmd :
      1. nslookup
      2. set type=mx
      3. your domain name.com
The output gives information about the Mx record of the domain name you entered.
𝗡𝗮𝗺𝗲 𝗦𝗲𝗿𝘃𝗲𝗿 𝗿𝗲𝗰𝗼𝗿𝗱 - This record points a dedicated name server to a domain, when you want to change the domain name server for a domain then this NS record should be updated. Every domain needs a name server so that the visitors in internet can reach them.
𝐏𝐓𝐑 𝐫𝐞𝐜𝐨𝐫𝐝 - This record knows as Pointer record can also be called as reverse DNS lookup record. When you send an email this record checks whether the domain name used to send this email, 
belongs to a legit Ip address (allocated for that domain).
PTR record for the IP address 192.0. 2.255 would be stored under "255.2.0. 192.in-addr. arpa"
In the next post we will look into rest of the DNS records, various ciphers, different types of servers in network etc.
-brb soon
(My Linkedin post is replicated here)