Hello Jinesh
I will attempt to answer your questions below:
Whats the difference between IPSec VPN and SSL VPN?
IPSEC, or IP Security is a VPN technology that functions on Layer 3. It secures data between two endpoints without any association to any specific application. Once it’s connected, you will be connected to the entire remote network as if you were physically there.
SSL VPN on the other hand functions at layer 7 or the application layer. It is used for secure web based communication over the internet. Unlike IPSec, SSL provides security to one specific application and not to all network traffic.
More details can be found here: https://supportforums.cisco.com/document/113896/quick-overview-ipsec-and-ssl-vpn-technologies
Is there any difference between UTM and Next Gen. Firewall?
It really depends on who you ask. Several experts may say that the UTM is a superset of the NGFW, others say that they are distinctly different. Still, others say that they are exactly the same. The following are a couple of general guidelines as to what the differences are:
A Unified threat management system is one that is designed to provide gateway antivirus, intrusion prevention, and URL blocking. You can think of it as functioning at higher layers of the OSI model and having generally lower throughput than NGFW due to the extra processing needed to perform these functions.
A next Generation firewall is designed to perform intrusion prevention and deep packet inspection and generally functions at lower levels of the OSI model. It generally has a higher throughput than UTMs.
Is there any difference between WAF and IPS?
An IPS watches network traffic in general as the packets flow through it. It attempts to match data in the packets against a signature database to detect anomalies. It can log, alert and be programmed to react to what it detects.
A Web Application Firewall is designed to protect web applications specifically from web-based attacks. WAFs are able to analyse up to layer 7 web application logic. Where an IPS matches data to signatures, WAFs deal with the behaviour and logic of what is requested and returned. It is more specialised that an IPS in this fashion.
Stateless vs. Stateful Servers
A stateful server remembers client data from one request to the next. In contrast, a stateless server does not retain session or status information about each communications partner for the uration of multiple requests. HTTP for example is a stateless protocol while TCP is a stateful protocol.
I hope this has been helpful!
Laz