This week, Mr. Zaki proceeds to next lecture which is Wireless Security. IEEE ratified wireless LAN 802.11 in 1997. Two pieces of 802.11 components are wireless station and access point. Wireless station is a desktop or laptop PC or PDA with a wireless NIC while Access point is a bridge between wireless and wired networks.
There are 2 types of 802.11 modes: Infrastructure mode and Ad-hoc mode. Infrastructure mode consists of Basic Service Set (BSS) and Extended Service Set. BSS just consist one access point while ESS consist two or more BSSs forming a single subnet. Ad-hoc mode also called peer-to-peer. It is an independent BSS. Below figure show that the Infrastructure mode and Ad-hoc mode.
802.11 have many types, such as 802.11a, 802.11g, 802.11b and 802.11n. Each of the types has its own speed and range. For example, 802.11b maximum specified range to 100 meters and average throughput of 4Mbps; while 802.11g average throughput of 30 Mbps and supports up to 54Mbps in 2.4 GHz range.
Next, Mr. Zaki explains the wireless signal will weakened by walls, floors and interference. This is because wireless LAN uses radio signal. So the access points try to avoid by windows, on external walls or line of sight to outside. Three basic security services defined by IEEE for the WLAN environment are Authentication, Integrity and Confidentiality. For the confidentiality purpose, messages are encrypted uses RC4. RC4 stands for Ron’s Code number 4, it is a symmetric key encryption and use key sizes from 1 bit to 2048 bits. RC4 generates a stream of pseudo random bits which mean it wills XOR with plaintext to create ciphertext.
Then, Mr. Zaki continue with new lecture; Firewall. Firewall could secure workstations and servers. It also can use as perimeter defence. Firewall consists of several types such as packet filtering firewall, stateful inspection firewall, application-level gateway (application proxy) and circuit-level gateway.
Packet filtering firewall is applies rules to packets in/out of firewall. It can base on information in packet header to say if forward or discard packet. It is an easier to manage and use firewall but less secure. This is because packet filter firewall cannot prevent attack on application bugs. It also do not support advanced user authentication.
Stateful inspection firewall is reviews packet header information but also keeps info on TCP connections. This type of firewall only allows incoming traffic to high-numbered ports for packets matching an entry in this directory.
Application-level gateway (application proxy) acts as relay of application-level traffic. It authenticates the users (valid user id & password). Application-level gateways more secure than packet filters but have higher overheads.
Circuit-Level Gateway is a circuit-level gateway does not permit an end to end TCP connection. It sets up two TCP connections, between itself to an inside user and between itself to an outside host.
In the end of the lecture, Mr. Zaki explains what is Firewall Basing and Firewall location.
There are 2 types of 802.11 modes: Infrastructure mode and Ad-hoc mode. Infrastructure mode consists of Basic Service Set (BSS) and Extended Service Set. BSS just consist one access point while ESS consist two or more BSSs forming a single subnet. Ad-hoc mode also called peer-to-peer. It is an independent BSS. Below figure show that the Infrastructure mode and Ad-hoc mode.
802.11 have many types, such as 802.11a, 802.11g, 802.11b and 802.11n. Each of the types has its own speed and range. For example, 802.11b maximum specified range to 100 meters and average throughput of 4Mbps; while 802.11g average throughput of 30 Mbps and supports up to 54Mbps in 2.4 GHz range.
Next, Mr. Zaki explains the wireless signal will weakened by walls, floors and interference. This is because wireless LAN uses radio signal. So the access points try to avoid by windows, on external walls or line of sight to outside. Three basic security services defined by IEEE for the WLAN environment are Authentication, Integrity and Confidentiality. For the confidentiality purpose, messages are encrypted uses RC4. RC4 stands for Ron’s Code number 4, it is a symmetric key encryption and use key sizes from 1 bit to 2048 bits. RC4 generates a stream of pseudo random bits which mean it wills XOR with plaintext to create ciphertext.
Then, Mr. Zaki continue with new lecture; Firewall. Firewall could secure workstations and servers. It also can use as perimeter defence. Firewall consists of several types such as packet filtering firewall, stateful inspection firewall, application-level gateway (application proxy) and circuit-level gateway.
Packet filtering firewall is applies rules to packets in/out of firewall. It can base on information in packet header to say if forward or discard packet. It is an easier to manage and use firewall but less secure. This is because packet filter firewall cannot prevent attack on application bugs. It also do not support advanced user authentication.
Stateful inspection firewall is reviews packet header information but also keeps info on TCP connections. This type of firewall only allows incoming traffic to high-numbered ports for packets matching an entry in this directory.
Application-level gateway (application proxy) acts as relay of application-level traffic. It authenticates the users (valid user id & password). Application-level gateways more secure than packet filters but have higher overheads.
Circuit-Level Gateway is a circuit-level gateway does not permit an end to end TCP connection. It sets up two TCP connections, between itself to an inside user and between itself to an outside host.
In the end of the lecture, Mr. Zaki explains what is Firewall Basing and Firewall location.
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