firewall and its working by mithila palamakula. firewall sits between two networks used to protect...
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Firewall and its working
ByMithila Palamakula
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Firewall
Sits between two networks Used to protect one from the other Places a bottleneck between the networks All communications must pass through the bottleneck which gives us a single
point of control
Need
Prevent attacks from untrusted networks.
Protecting data integrity
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administerednetwork
publicInternet
firewalltrusted “good guys” untrusted “bad guys”
Computer Networking: Kurose, Ross
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Evolution of firewalls:
1. Packet filters
2. Stateful packet filters
3. Application gateways
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Packet filter Developed by Bill Cheswick and Steve Bellovin. Network layer. Packet filter drop or reject packet. Simple.
Application gateway or proxy Gene Spafford, Bill Cheswick, Marcus Ranum. Application layer.
Stateful packet filters Dave Pressetto, Janardan Sharma and Kshity Nigam. Between DataLink and Network layer. Connection column in addition to packet filters.
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Packet Filters
Compare network and transport protocols to a database of rules and then forward only the packets that meet the criteria of the rules.
Implemented in routers and sometimes in the TCP/IP stacks of workstation machines
In a router a filter prevents suspicious packets from reaching your network
In a TCP/IP stack it prevents that specific machine from responding to suspicious traffic
https://www.google.com/search?q=packet+filters+firewall&espfw_invisible_filter.gif%3
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Proxies
Proxy is a combination of a client and a server; internal users send requests to the server portion of the proxy which then sends the internal users requests out through its client
Hides internal users from the external network by hiding them behind the IP of the proxy
Prevents low level network protocols from going through the firewall eliminating some of the problems with NAT
Restricts traffic to only the application level protocols being proxied
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Application gateways It is an application- specific server through which all application data must pass.
Computer Networking: Kurose, Ross
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Procedure for application gateways: All telnet users to telnet through gateway. Gateway sets up telnet connection to destination host Router filter blocks all telnet connections.
Deployment Corporate gateway ( common one) Internal segment gateway Server-based firewall
Introduction to firewall: Jason Pan
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Conclusion
Acts as a barrier between two or more networks.
Stateful is the leading firewall technology.
A small leak in firewall effects the whole organization network.
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Questions?
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References
Computer Networking: A top down approach, sixth edition, James F Kurose, Keith W Ross, Pearson
http://www.howstuffworks.com/firewall.htm
http://searchsecuritychannel.techtarget.com/feature/Network-firewall-vendors
http://www.wikepedia.org/
http://technet.Microsoft.com
http://www.bu.edu/
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Thank you