2. WHAT IS FIREWALL?
• Firewall is anything, hardware or software, that
monitors transmission of packets of digital information
that attempt to pass the perimeter of a network.
• Firewalls perform two basic security functions:
• (Network Traffics) Packet filtering
• Application proxy
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3. 3
FIREWALL SECURITY FEATURES
Some firewall manufacturers add features like:
Logging unauthorized accesses into/out of a network
Providing VPN link to another network
Authenticating users
Shielding hosts inside the network from hackers
Caching data
Filtering content considered inappropriate or dangerous
4. 4
FIREWALL COMPONENTS
• Packet filter
• Proxy server
• Authentication system
• Software that performs Network Address
Translation (NAT)
• Some firewalls:
• Can encrypt traffic
• Help establish VPNs
• Come packaged in a hardware device that also
functions as a router
• Make use of a bastion host
5. TYPES OF FIREWALL
• Client Firewall
• Windows firewall
• For a computer
• Network firewall
• Between private network & public network
• VPN, Routing, . . . .
• For each network by its rules
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6. NETWORK TRAFFIC
• Inbound traffic
• Outbound traffic
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Source Destination
(Requester) (Replier)
Ping 192.168.0.1 ICMP
Outbound Inbound
My Service (My internal network or my PC
His service
14. LINUX IPTABLES FIREWALL
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Client Firewall (iptables)
#iptables –L INPUT (for input chain type or Inbound)
#iptables –L OUTPUT (for output chain type or outbound)
List
15. LINUX IPTABLES FIREWALL
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# iptables –A INPUT –s 192.168.0.1 –d 192.168.0.254 –p ICMP –j DROP
# iptables –A INPUT –s 192.168.0.0/24 –d 192.168.0.254/32 –p ICMP –j DROP
# iptables –L INPUT
# service iptables save
# service iptables start
Append INBOUND Rules in iptables ( Client Firewall )
Append Source Destination Protocol Jump
# iptables –D INPUT 1
Delete Line Number
