A firewall is a way or mechanism that applies both to the
hardware, software or the system itself. The purpose of the use of a firewall is
to protect by filtering, limiting, or even reject any or all
relationships or activities of a segment on a private network with external network that is not
is the scope. These segments can be a workstation,servers, routers, or a local area network (LAN). Simply put, the firewall configuration
are as follows:
hardware, software or the system itself. The purpose of the use of a firewall is
to protect by filtering, limiting, or even reject any or all
relationships or activities of a segment on a private network with external network that is not
is the scope. These segments can be a workstation,servers, routers, or a local area network (LAN). Simply put, the firewall configuration
are as follows:
pc <==> firewall <==> internet
The first time, firewall to the computer by using the principle
"Non-routing" on a Unix host that uses two pieces network interface card,
The first network interface card to connect to the Internet (other network) while
others connected to the pc (with the note did not happen "route" between the two
network interface card in this pc). To be able to connect to the Internet, should be
entering the firewall server (can be remote, or directly), then use
existing resources at this computer to connect to the Internet (other network)
and if necessary to save the file / data, then the file can be stored temporarily on your pc
mengkopikannya your firewall and then to pc. Thus, the Internet can not
directly related to the pc. Such methods have many
shortages that developed in various shapes, configurations and types of firewalls
with various rules in it. Firewalls are generally reserved for
serving:
1. Machinery / ComputerEach machine / computer that is connected directly to the external network or the internet
and wants all contained on their computers protected.
2. Network
Computer network consisting of more than one computer and various types of
network topology is used, whether owned by companies, organizations
and so forth.
Characteristics of a firewallIn general, the characteristics of a firewall can be explained as follows:
1. The whole relationship / activities from inside to outside, must pass through the firewall. This
can be done in a way to block / restrict all access to network
local, except when passing the firewall. Many forms of network
This configuration allows to materialize.
2. Only the activities listed / known that can pass / make relationships,
this can be done by setting the local security policy on the configuration.
3. Firewall itself should be relatively immune or strong against attacks / weaknesses. Case
this means the use and reliable system with which system
relatively safe.
Techniques used by a firewall1. Service control (control of the service)
Based on the types of services used on the Internet and can be accessed either
for into or out of the firewall. Usually the firewall will check the IP number
Address and port number that is in use both on TCP and UDP,
can even be equipped with software for proxy which will receive and
translates every request for a service before it allows it.
2. Direction Conrol (control of direction)
Under the direction of the various requests (request) to the services that will
recognized and permitted through the firewall.3. User control (control of the user)Based on user / user to be able to run a service, meaning there
existing users who can and who can not run a service, this in
karenakan user is not allowed to pass through the firewall. Usually
used to restrict users from the local network to access the exit,
but it can also be applied to restrict the user from the outside.
4. Behavior Control (control over their treatment)
Based on how many services have been used. For example, a firewall
can filter the email to address / prevent spam.Firewall Types1. Packet Filtering Router
Packet filtering is applied in a way better manage all the IP packet
towards, past or will be addressed by the packet. In this type of packet
will be regulated or whether to be received and forwarded or rejected.
Packet filtering is configured to filter the packet that will be
transfer in both directions (both from and to the local network). Filtering rules
based on the IP header and transport header, which also includes the beginning address (IP)
and destination address (IP), transport protocol used (UDP, TCP), as well as
port number used. The advantages of this type is easy to
implemented, transparent to users, relatively faster.
The weakness was quite complicated to set its package to be
appropriately filtered, and the weak in terms of authentication.
The attacks that can occur in this type of firewall are:
- IP address spoofing: Intruder (intruders) from the outside can do
This in a way to include / use the ip address of local network
which has been allowed to go through a firewall.
- Source routing attacks: This type is not to analyze the routing information
source IP, making it possible to bypass a firewall.
- Tiny fragment attacks: Intruder IP divide into parts
(Fragments) which are smaller and forcing the division of information
about the TCP header. This type of attack designed to deceive
filtering rules that depend on information from the TCP
header. Striker hoping only part (fragment) only the first
which will be examined and the rest will be able to pass freely. Case
This can be in tanggulangi by refusing all packets with
TCP protocol and had Offset = 1 in the IP fragment (the IP)
2. Application-Level Gateway
Application-level Gateway is also commonly known as a proxy server
serves to reinforce / deliver the application flow. This type will be set
all relations that uses the application layer, whether it is FTP, HTTP,
Gopher etc.How it works is if there are users who use one application
such as FTP to access remotely, the gateway will prompt the user
enter the address of the remote host to be accessed. When a user submits
useer ID and other information according to the gateway will perform
relation to the application found on the remote host, and
data channel between the two points. if the data is not appropriate then
firewall will not forward such data or reject it. Furthermore,
on this type of firewall can be configured to only support some
application only and reject other applications to pass through the firewall. Excess
is relatively more secure than the type of packet filtering router is easier to
checks (audits) and records (logs) all incoming data streams at the level
application. The drawback is the excessive additional processing at every
relationship. which will result in a connection there are two connections
between the user and the gateway, where gateway will check and forward the
all flows from two directions.
3. Circuit-level Gateway
This third type can be a stand-alone system, or can also
is a special function which is formed from the type of application-level gateway.tipe
This does not allow TCP connections end to end (direct)
How it works: Gateway will arrange a second TCP connection, the first between
his will (i) with TCP on the local user (inner host) and a longer between
his will (i) with TCP outside users (outside the host). When two relations
materialize, the gateway will deliver TCP segments from one relationship to the
other without examining its contents. Lies in the determination of its security functions
Which relationship on the permits. Use of this type are usually driven
administrators believe with internal users (internal users).
"Non-routing" on a Unix host that uses two pieces network interface card,
The first network interface card to connect to the Internet (other network) while
others connected to the pc (with the note did not happen "route" between the two
network interface card in this pc). To be able to connect to the Internet, should be
entering the firewall server (can be remote, or directly), then use
existing resources at this computer to connect to the Internet (other network)
and if necessary to save the file / data, then the file can be stored temporarily on your pc
mengkopikannya your firewall and then to pc. Thus, the Internet can not
directly related to the pc. Such methods have many
shortages that developed in various shapes, configurations and types of firewalls
with various rules in it. Firewalls are generally reserved for
serving:
1. Machinery / ComputerEach machine / computer that is connected directly to the external network or the internet
and wants all contained on their computers protected.
2. Network
Computer network consisting of more than one computer and various types of
network topology is used, whether owned by companies, organizations
and so forth.
Characteristics of a firewallIn general, the characteristics of a firewall can be explained as follows:
1. The whole relationship / activities from inside to outside, must pass through the firewall. This
can be done in a way to block / restrict all access to network
local, except when passing the firewall. Many forms of network
This configuration allows to materialize.
2. Only the activities listed / known that can pass / make relationships,
this can be done by setting the local security policy on the configuration.
3. Firewall itself should be relatively immune or strong against attacks / weaknesses. Case
this means the use and reliable system with which system
relatively safe.
Techniques used by a firewall1. Service control (control of the service)
Based on the types of services used on the Internet and can be accessed either
for into or out of the firewall. Usually the firewall will check the IP number
Address and port number that is in use both on TCP and UDP,
can even be equipped with software for proxy which will receive and
translates every request for a service before it allows it.
2. Direction Conrol (control of direction)
Under the direction of the various requests (request) to the services that will
recognized and permitted through the firewall.3. User control (control of the user)Based on user / user to be able to run a service, meaning there
existing users who can and who can not run a service, this in
karenakan user is not allowed to pass through the firewall. Usually
used to restrict users from the local network to access the exit,
but it can also be applied to restrict the user from the outside.
4. Behavior Control (control over their treatment)
Based on how many services have been used. For example, a firewall
can filter the email to address / prevent spam.Firewall Types1. Packet Filtering Router
Packet filtering is applied in a way better manage all the IP packet
towards, past or will be addressed by the packet. In this type of packet
will be regulated or whether to be received and forwarded or rejected.
Packet filtering is configured to filter the packet that will be
transfer in both directions (both from and to the local network). Filtering rules
based on the IP header and transport header, which also includes the beginning address (IP)
and destination address (IP), transport protocol used (UDP, TCP), as well as
port number used. The advantages of this type is easy to
implemented, transparent to users, relatively faster.
The weakness was quite complicated to set its package to be
appropriately filtered, and the weak in terms of authentication.
The attacks that can occur in this type of firewall are:
- IP address spoofing: Intruder (intruders) from the outside can do
This in a way to include / use the ip address of local network
which has been allowed to go through a firewall.
- Source routing attacks: This type is not to analyze the routing information
source IP, making it possible to bypass a firewall.
- Tiny fragment attacks: Intruder IP divide into parts
(Fragments) which are smaller and forcing the division of information
about the TCP header. This type of attack designed to deceive
filtering rules that depend on information from the TCP
header. Striker hoping only part (fragment) only the first
which will be examined and the rest will be able to pass freely. Case
This can be in tanggulangi by refusing all packets with
TCP protocol and had Offset = 1 in the IP fragment (the IP)
2. Application-Level GatewayApplication-level Gateway is also commonly known as a proxy server
serves to reinforce / deliver the application flow. This type will be set
all relations that uses the application layer, whether it is FTP, HTTP,
Gopher etc.How it works is if there are users who use one application
such as FTP to access remotely, the gateway will prompt the user
enter the address of the remote host to be accessed. When a user submits
useer ID and other information according to the gateway will perform
relation to the application found on the remote host, and
data channel between the two points. if the data is not appropriate then
firewall will not forward such data or reject it. Furthermore,
on this type of firewall can be configured to only support some
application only and reject other applications to pass through the firewall. Excess
is relatively more secure than the type of packet filtering router is easier to
checks (audits) and records (logs) all incoming data streams at the level
application. The drawback is the excessive additional processing at every
relationship. which will result in a connection there are two connections
between the user and the gateway, where gateway will check and forward the
all flows from two directions.
3. Circuit-level Gateway
This third type can be a stand-alone system, or can also
is a special function which is formed from the type of application-level gateway.tipe
This does not allow TCP connections end to end (direct)
How it works: Gateway will arrange a second TCP connection, the first between
his will (i) with TCP on the local user (inner host) and a longer between
his will (i) with TCP outside users (outside the host). When two relations
materialize, the gateway will deliver TCP segments from one relationship to the
other without examining its contents. Lies in the determination of its security functions
Which relationship on the permits. Use of this type are usually driven
administrators believe with internal users (internal users).
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