Firewalls:
It is a basic protection against internet based hackers .firewall is a physical Device that filters packets heading on the network .its filtering basic purpose is to block the attempts to harm our network.If an email is sent and there is an attachment file in it. now when it comes to the network, there is a firewall in the network ,firewall rejects the email and said sorry ,Attachments is not allowed, more ever we don’t know that we had email . By using firewall, we can simply block any particular ip, like if ever request come from x ip to exit its traffic then don’t allow it. similarly we can block any particular port number .more ever we can block any particular protocol.If we want that user not receive email then open pop 3 port .thats happen a lot when new firewalls are put in .if we want that users cant send the email then open Smtp port .if we want stop users to access web, we block http port.
Proxy servers:
a proxy server is a server that acts as an intermediary for requests from the clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resources.If the request is validated by the filter, the proxy provides the resource by connecting to the relevant server and requesting the service on behalf of the client. ble from a different server. The proxy server evaluates the request according to its filtering rules.Through proxy server , communication is fast & secondly when it stores the copy receive from the server it forwards the copy to the client,more ever it also stores the copy in its cache .
hackers hack due to following reasons :
1)just for fun
2)lock our hardware and blackmail us for money.
3)to know sensitive info like credit card number.
4)to embarrass some company to show them their network security is nil and they can do them harm if they want .
denial of service attack:
denial-of-service attack (DoS attack) is a network attack attempt.in this attack the attackers overwhelm the server with tcp connection requests.due to these requests, it make the computer resource unavailable to its intended users due to the congestion .Actually server is so busy to answer these connection requests from the attacker so it cant answer the genuine users and server may crash down due to the load.its thousands of connection requests .this attack is more to damage the data rather than steal data.
To steal the data we have reconnaissance attacks and access attacks.
In Reconnaissance attacks ,intruder use different techs to know strengths and weaknesses Of A network.After getting that info ,intruder comes back and attack the network.
In access attacks we steal the data for our personal use or financial use .
Adaptive security appliance (ASA):
Handles vpns connectivity,nw security and works cheap .when see documentation regarding asa we see term anti x.we gather all stuff in one material like anti virus,anti spam,all antis in it.
Computer security is not something that we add when we need it.for security we need IDS (intruder detection system)& IPS(intruder prevention system).in IDS we watched the packets of data coming across the network & compared that traffic to the configured rules.if something suspicious is detected then there is an alarm.while IPS has all good features of IDS and it not only detects the malicious traffic but it also stops that traffic.
Now in the end lets talk about viruses,worms & trojan horses.All of them are malicious programes that can cause damage to our computer.but there is a difference among them.
VIRUSES:
computer virus attaches itself to a file/program enabling them to spread from 1 computer to other.and leaves viruses as travel.but a virus cant be spread without the human action.for virus spread ,it needs human action
WORMS:
worms similar in design to viruses & consider sub class of viruses.major difference in viruses and worms is that worms does not need human action.it replicates on its own which is the major danger in worms.an example of worm is to send a copy of itself to everyone listed in a email address book.
TROJAN HORSE:
Trojan horses, also called as trojans , are programs that pretends to be something else. common scenario is that a person receives what looks like a legitimate email, which may even appear to be from a friend or work colleague.
The file may look like a photograph, sound file or even a game. When user tries to open it ,it appears that nothing has happened. If they are unlucky, they may just have installed something quite nasty on their hard drive.
It could be a basic file that deletes a handful of system files, or it may be something a little more advanced, that can even allow other people full access to your system and files.
