Describe an access list and what it does?

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Describe an access list and what it does? ..

Answer / kiran javvaji ( wipro )

Access lists controls the traffic flow between the routers
its a layer three security and is also called as packet
filtering firewall
Access lists are of three types
1.Standard access list
2.Extended access list
3.Named access list

1.standard access list :

acl no lies between 1-99
Let us say two routers are there and you want to block
packets from a network or a host or from a particular
subnet it can be impelemented using standard access list
but the disadvantage is at the same time even you are
unable to send the data to that particular network or to
host or to that subnet ,..means two way communication is
stopped and it is to be implemented at your end means at
destination end

2.Extended access List :

acl no lies between 100- 199
Extended access list also same as stnadard acl
except ..only one way communication is stopped means
evanthough you are unable to receive the packets from
paticular source you can send the packets to that
particular source and one more major diff is it is
implemented at the source end and one more advantage
is we can block particular services like http.ftp,snmp etc

Sorry i dont know much abt named access list :)

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Describe an access list and what it does? ..

Answer / mak_alam000

access list is service which is used on router for security purpose , u can say its filtering the packets
there are three type ACL
standard
extended
named

standard
by standard u can block a subnet or system

extended
here u can also block subnet as well as a particular services but u cant do this on standard .

named
named ACL can be standard or extended here no ACL no it uses
name .