Network security 


In nearby networks, digital neighborhood region networks (vlans) are on occasion configured as a safety measure to restriction the number of hosts susceptible to layer 2 attacks. Vlans create network obstacles, over which broadcast (arp, dhcp) visitors cannot pass.

Digital nearby region network

The common shape of vlan is a port-based totally vlan. On this vlan shape, the switch ports are grouped into vlan the usage of transfer control software program. Hence a unmarried bodily switch can act as more than one digital switches.


Employment of vlans provide site visitors isolation. It divides the huge broadcast layer 2 network into smaller logical layer 2 networks and consequently reduces the scope of attacks consisting of arp/dhcp spoofing. Facts frames of 1 vlan can pass from/to within ports belonging to the same vlan best. The frames forwarding among  vlans is carried out via routing.

Vlans typically span a couple of switches as shown inside the diagram above. The hyperlink between trunk ports carry frames of all vlans defined over multiple physical switches. For this reason, vlan frames forwarded among switches can’t be simple ieee 802.1 ethernet layout frames. Due to the fact, those body circulate on same bodily link, they now need to hold vlan identification records. Ieee 802.1q protocol provides/gets rid of extra header fields to straightforward ethernet frames forwarded among trunk ports.

Wi-fi local area network is a community of wi-fi nodes inside a confined geographic area, which includes an office constructing or school campus. Nodes are able to radio conversation.

Wi-fi lan

Wi-fi lan is usually implemented as extensions of existing stressed out lan to offer network get right of entry to with device mobility. The most extensively implemented wireless lan technology are based at the ieee 802.11 standard and its amendments.

The 2 major additives in wireless lan are −

Get admission to factors (aps) − those are base stations for the wireless network. They transmit and receive radio frequencies to talk with wi-fi clients.
Wireless customers − these are computing devices which are geared up with a wi-fi network interface card (wnic). Laptops, ip telephones, pdas are ordinary examples of wireless clients.

Many organizations have applied wireless lans. These networks are growing phenomenally. It’s miles therefore, crucial to understand threats in wireless lans and examine the common safety measure to ensure community security.

Attacks in wi-fi lan

The typical assaults which can be finished on wireless lan are −

Eavesdropping − the attacker passively monitors wireless networks for facts, together with authentication credentials.
Masquerading − the attacker impersonates a certified person and gains get right of entry to and privileges on wi-fi networks.
Visitors analysis − the attacker monitors transmissions through wi-fi networks to perceive conversation patterns and members.h
Denial of carrier − the attacker prevents or restricts the regular use or control of wi-fi lan or network devices.
Message change/replay − the attacker alters or replies to a valid message sent through wireless networks with the aid of deleting, adding to, converting, or reordering it.
Security features in wireless lan

Safety features offer way to defeat assaults and manipulate risks to the networks. Those are community management, operation, and technical measures. We describe underneath the technical measures followed to ensure confidentiality, availability, and integrity of facts transmitted thru wireless lans.

In wi-fi lans, all aps ought to be configured to offer security via encryption and client authentication. The kinds of schemes utilized in wireless lan to provide safety are as follows −


Stressed out equivalent privacy (wep)

It is an encryption set of rules built into the 802.Eleven trendy to comfy wi-fi networks. Wep encryption makes use of the rc4 (rivest cipher four) move cipher with forty-bit/104-bit keys and a 24-bit initialization vector. It may additionally offer endpoint authentication.

802.11i protocol

In this protocol severa and stronger varieties of encryption are viable. It has been evolved to replace vulnerable wep scheme. It affords key distribution mechanism. It supports one key according to station, and does no longer use the identical key for all. It uses authentication server break free the access point.

Ieee802.11i mandates the usage of a protocol named counter mode with cbc-mac protocol (ccmp). Ccmp offers confidentiality and integrity of the records transferred and authenticity of the sender. It is based at the advanced encryption standard (aes) block cipher.

The ieee802.11i protocol has 4 phases of operation

Sta and ap talk and find out mutual safety abilities such as supported algorithms.
Sta and as mutually authenticate and together generate master key (mk). Ap acts as “skip thru”.
Sta derives pairwise grasp key (pmk). As derives equal pmk and sends to ap.
Sta, ap use pmk to derive temporal key (tk) for use for message encryption and data integrity.

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