Tuesday, 15 February 2022

What is Time-based access-list? How to configure Time-based access-list?


Time-based access-list is type of access-list which allows network access on the basis of given time period. It is useful when you want to place restrictions on outbound or inbound traffic on the basis of particular day and time periods.

Sometimes it may be useful if you want to block particular traffic on specific days or during business hours.


 

Time-based access-list
Time-based access-list
Time-based access-list is Easy to implement and Its provides good control over the network traffic to an admin as the traffic can be denied or permitted on the basis of time.

lets configure Time-based access-list 

Topology:




  • configure the topology as per the diagram
  • configure IP addresses to their ports 
  • configure EIGRP AS 65100 for routing
  • make sure PC communicate loopback 0 172.16.1.1 network before configure Time-based access-list .
  • configure Time-based access-list  on router 1 and block PC ICMP msg for 172.16.1.1 network.


R1(config)#interface fastEthernet 0/0

R1(config-if)#ip address 192.168.1.1 255.255.255.0

R1(config-if)#no shutdown

R1(config-if)#exit


R1(config)#interface ethernet 6/0

R1(config-if)#ip address 10.1.1.1 255.0.0.0

R1(config-if)#no shutdown



R1#show ip interface brief

Interface              IP-Address      OK? Method Status                Protocol

FastEthernet0/0        192.168.1.1     YES manual up                    up

Ethernet6/0            10.1.1.1        YES manual up                    up



R2(config)#interface fastEthernet 0/0
R2(config-if)#ip address 192.168.1.2 255.255.255.0
R2(config-if)#no shutdown
R2(config-if)#exit

R2(config)#interface serial 4/0
R2(config-if)#ip address 1.1.1.1 255.0.0.0
R2(config-if)#no shutdown
R2(config-if)#exit



R3(config)#interface serial 4/0
R3(config-if)#ip address 1.1.1.2 255.0.0.0
R3(config-if)#no shutdown
R3(config-if)#exit

R3(config)#interface loopback 0
R3(config-if)#ip address 172.16.1.1 255.255.0.0

R3(config-if)#do show ip int br
Interface              IP-Address      OK? Method Status                Protocol
Serial4/0              1.1.1.2         YES manual up                    up
Loopback0              172.16.1.1      YES manual up                    up


{CONFIGURE PC IP ADDRESS WITH DEFAULT GATEWAY}

IP 10.1.1.2 255.0.0.0 10.1.1.1




R1(config)#router eigrp 65100

R1(config-router)#network 192.168.1.0

R1(config-router)#network 10.0.0.0

R1(config-router)#no auto-summary

R1(config-router)#exit


*Feb 15 12:47:49.483: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 192.168.1.2 (FastEthernet0/0) is up: new adjacency




R2(config)#router eigrp 65100
R2(config-router)#network 1.0.0.0
R2(config-router)#network 192.168.1.0
R2(config-router)#no auto-summary

*Feb 15 12:47:13.891: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 192.168.1.1 (FastEthernet0/0) is up: new adjacency

R2(config-router)#no auto-summary
R2(config-router)#exit






R3(config)#router eigrp 65100
R3(config-router)#network 172.16.0.0
R3(config-router)#network 1.0.0.0
R3(config-router)#no auto-summary

*Feb 15 12:48:24.771: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 1.1.1.1 (Serial4/0) is up: new adjacency
R3(config-router)#exit



PC1> ping 10.1.1.1
84 bytes from 10.1.1.1 icmp_seq=1 ttl=255 time=96.577 ms
84 bytes from 10.1.1.1 icmp_seq=2 ttl=255 time=35.450 ms
84 bytes from 10.1.1.1 icmp_seq=3 ttl=255 time=9.170 ms
84 bytes from 10.1.1.1 icmp_seq=4 ttl=255 time=5.948 ms
84 bytes from 10.1.1.1 icmp_seq=5 ttl=255 time=5.712 ms

PC1> ping 192.168.1.1
84 bytes from 192.168.1.1 icmp_seq=1 ttl=255 time=12.731 ms
84 bytes from 192.168.1.1 icmp_seq=2 ttl=255 time=5.809 ms
84 bytes from 192.168.1.1 icmp_seq=3 ttl=255 time=7.586 ms
84 bytes from 192.168.1.1 icmp_seq=4 ttl=255 time=14.573 ms
84 bytes from 192.168.1.1 icmp_seq=5 ttl=255 time=14.912 ms

PC1> ping 1.1.1.1
84 bytes from 1.1.1.1 icmp_seq=1 ttl=254 time=32.289 ms
84 bytes from 1.1.1.1 icmp_seq=2 ttl=254 time=26.462 ms
84 bytes from 1.1.1.1 icmp_seq=3 ttl=254 time=28.834 ms
84 bytes from 1.1.1.1 icmp_seq=4 ttl=254 time=32.267 ms
84 bytes from 1.1.1.1 icmp_seq=5 ttl=254 time=27.565 ms

PC1> ping 172.16.1.1
84 bytes from 172.16.1.1 icmp_seq=1 ttl=253 time=86.535 ms
84 bytes from 172.16.1.1 icmp_seq=2 ttl=253 time=44.981 ms
84 bytes from 172.16.1.1 icmp_seq=3 ttl=253 time=39.510 ms
84 bytes from 172.16.1.1 icmp_seq=4 ttl=253 time=49.432 ms
84 bytes from 172.16.1.1 icmp_seq=5 ttl=253 time=52.414 ms

PC1> ping 172.16.1.1
84 bytes from 172.16.1.1 icmp_seq=1 ttl=253 time=50.518 ms
84 bytes from 172.16.1.1 icmp_seq=2 ttl=253 time=49.394 ms
84 bytes from 172.16.1.1 icmp_seq=3 ttl=253 time=39.684 ms
84 bytes from 172.16.1.1 icmp_seq=4 ttl=253 time=50.800 ms
84 bytes from 172.16.1.1 icmp_seq=5 ttl=253 time=52.605 ms




R1#clock set 0:10:0 1 july 2021


*Jul  1 00:10:00.003: %SYS-6-CLOCKUPDATE: System clock has been updated from 13:01:35 UTC Tue Feb 15 2022 to00:10:00 UTC Thu Jul 1 2021, 


R1(config)#time-range Work_Hours

R1(config-time-range)#absolute start 00:15 1 july 2021

R1(config-time-range)#absolute start 00:15 1 july 2021 end 00:20 1 july 2021

R1(config-time-range)#exit



R1(config)#time-range NO_ICMP

R1(config-time-range)#periodic ?

  Friday     Friday

  Monday     Monday

  Saturday   Saturday

  Sunday     Sunday

  Thursday   Thursday

  Tuesday    Tuesday

  Wednesday  Wednesday

  daily      Every day of the week

  weekdays   Monday thru Friday

  weekend    Saturday and Sunday


R1(config-time-range)#periodic weekdays 0:15 to 0:20

R1(config-time-range)#exit


R1(config)#ip access-list extended Work_Hours

R1(config-ext-nacl)#$ost 10.1.1.2 host 172.16.1.1 time-range N0_ICMP

R1(config-ext-nacl)#permit ip any any

R1(config-ext-nacl)#end


R1(config)#interface fastEthernet 0/0

R1(config-if)#ip access-group Work_Hours out

R1(config-if)#exit



PC1> ping 172.16.1.1
*10.1.1.1 icmp_seq=1 ttl=255 time=22.213 ms (ICMP type:3, code:13, Communication administratively prohibited                                                            )
*10.1.1.1 icmp_seq=2 ttl=255 time=12.513 ms (ICMP type:3, code:13, Communication administratively prohibited                                                            )
*10.1.1.1 icmp_seq=3 ttl=255 time=9.375 ms (ICMP type:3, code:13, Communication administratively prohibited)
*10.1.1.1 icmp_seq=4 ttl=255 time=9.523 ms (ICMP type:3, code:13, Communication administratively prohibited)
*10.1.1.1 icmp_seq=5 ttl=255 time=3.403 ms (ICMP type:3, code:13, Communication administratively prohibited)








Facebook



Twitter




LINKEDIN








 


 


Instagram

Facebook


Twitter



LINKEDIN








Friday, 11 February 2022

What is Network time protocol? How to configure NTP on router?

 Network time protocol provides pretty much what its name says time. provide correct time to all network devices. in other words, NTP synchronizes the clock of the computer system over packet switch, variable-latency data networks. Correct network time within the network is important.

Correct time allows the tracking of the event in the network in the correct order. Cock synchronize is critical for the correct interpretation of events within the Syslog data.

Advantages of NTP : 

It provides internet synchronization between the computer devices.

NTP provides enhanced security within the premises.

NTP is used in authentication systems.

NTP  provides network acceleration which helps in troubleshooting problems.


let's see the configuration on the router:

Topology:


Goal :

  • configure the topology as per the diagram above.
  • configure the IP addresses to their ports 
  • configure routing with EIGRP AS 65100 and advertise all the ports 
  • configure NTP on router 3, server address will loopback 0 
  • make sure the rest of the routers get time which is provided by our NTP server.

R1(config)#interface fastEthernet 0/0
R1(config-if)#ip address 10.1.1.1 255.0.0.0
R1(config-if)#no shutdown
R1(config-if)#no keepalive
R1(config-if)#exit

R1(config)#interface serial 4/0
R1(config-if)#ip address 1.1.1.1 255.0.0.0
R1(config-if)#no shutdown
R1(config-if)#exit

R1(config)#interface loopback 0
R1(config-if)#ip address 192.168.1.1 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#exit

R1(config)#do show ip int br
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        10.1.1.1        YES manual up                    up
Serial4/0                     1.1.1.1         YES manual up                    up
Loopback0             192.168.1.1     YES manual up                    up

R2(config)#interface fastEthernet 0/0
R2(config-if)#ip address 20.1.1.1 255.0.0.0
R2(config-if)#no shutdown
R2(config-if)#no keepalive
R2(config-if)#exit

R2(config)#interface serial 4/0
R2(config-if)#ip address 1.1.1.2 255.0.0.0
R2(config-if)#no shutdown
R2(config-if)#exit


R2(config)#interface serial 4/1
R2(config-if)#ip address 2.2.2.1 255.0.0.0
R2(config-if)#no shutdown
R2(config-if)#exit

R2(config)#interface loopback 0

R2(config-if)#ip address 192.168.2.2 255.255.255.0
R2(config-if)#no shutdown
R2(config-if)#exit

R2(config)#do show ip int br
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        20.1.1.1        YES manual up                    up
Serial4/0                      1.1.1.2         YES manual up                    up
Serial4/1                      2.2.2.1         YES manual up                    up
Loopback0              192.168.2.2     YES manual up                    up

R3(config)#interface fastEthernet 0/0
R3(config-if)#ip address 30.1.1.1 255.0.0.0
R3(config-if)#no shutdown
R3(config-if)#no keepalive
R3(config-if)#exit


R3(config)#interface serial 4/1
R3(config-if)#ip address 2.2.2.2 255.0.0.0
R3(config-if)#no shutdown
R3(config-if)#exit

R3(config)#interface serial 4/2
R3(config-if)#ip address 3.3.3.2 255.0.0.0
R3(config-if)#no shutdown
R3(config-if)#exit

R3(config)#interface loopback 0
R3(config-if)#ip address 192.168.3.3 255.255.255.0
R3(config-if)#no shutdown
R3(config-if)#exit

R3(config)#do show ip int br
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        30.1.1.1        YES manual up                    up
Serial4/1              2.2.2.2         YES manual up                    up
Serial4/2              3.3.3.2         YES manual up                    up
Loopback0              192.168.3.3     YES manual up                    up


R4(config)#interface fas
R4(config)#interface fastEthernet 0/0
R4(config-if)#ip address 40.1.1.1 255.0.0.0
R4(config-if)#no shutdown
R4(config-if)#no keepalive
R4(config-if)#exit

R4(config)#interface serial 4/2
R4(config-if)#ip address 3.3.3.3 255.0.0.0
R4(config-if)#no shutdown
R4(config-if)#exit

R4(config)#interface loopback 0
R4(config-if)#ip address 192.168.4.4 255.255.255.0
R4(config-if)#exit

R4(config)#do show ip int br
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        40.1.1.1        YES manual up                    up
Serial4/2              3.3.3.3         YES manual up                    up
Loopback0              192.168.4.4     YES manual up                    up


R1(config)#router eigrp 65100
R1(config-router)#network 10.0.0.0
R1(config-router)#network 1.0.0.0
R1(config-router)#network 192.168.1.0
R1(config-router)#no auto-summary
R1(config-router)#exit


R2(config)#router eigrp 65100
R2(config-router)#network 20.0.0.0
R2(config-router)#network 1.0.0.0
R2(config-router)#network 2.0.0.0
R2(config-router)#network 192.168.2.0
R2(config-router)#no auto-summary
R2(config-router)#exit

*Feb 11 12:54:25.263: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 1.1.1.1 (Serial4/0) is up: new adjacency


R3(config)#router eigrp 65100
R3(config-router)#network 30.0.0.0
R3(config-router)#network 2.0.0.0
R3(config-router)#network 2.0.0.0
R3(config-router)#network 3.0.0.0
R3(config-router)#network 192.168.3.0
R3(config-router)#no au
R3(config-router)#no auto-summary
R3(config-router)#exit
R3(config)#end

*Feb 11 12:54:58.699: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 2.2.2.1 (Serial4/1) is up: new adjacency 

*Feb 11 12:55:29.027: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 3.3.3.3 (Serial4/2) is up: new adjacency


R4(config)#router eigrp 65100
R4(config-router)#network 40.0.0.0
R4(config-router)#network 3.0.0.0
R4(config-router)#network 192.168.4.0
R4(config-router)#no auto-summary
R4(config-router)#exit
R4(config)#end

*Feb 11 12:55:08.211: %DUAL-5-NBRCHANGE: EIGRP-IPv4 65100: Neighbor 3.3.3.2 (Serial4/2) is up: new adjacency

R1#show eigrp protocols
EIGRP-IPv4 Protocol for AS(65100)
  Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  NSF-aware route hold timer is 240
  Router-ID: 192.168.1.1
  Topology : 0 (base)
    Active Timer: 3 min
    Distance: internal 90 external 170
    Maximum path: 4
    Maximum hopcount 100
    Maximum metric variance 1


R1#show ip route eigrp
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

D     2.0.0.0/8 [90/2681856] via 1.1.1.2, 00:02:52, Serial4/0
D     3.0.0.0/8 [90/3193856] via 1.1.1.2, 00:02:00, Serial4/0
D     20.0.0.0/8 [90/2172416] via 1.1.1.2, 00:02:19, Serial4/0
D     30.0.0.0/8 [90/2684416] via 1.1.1.2, 00:02:05, Serial4/0
D     40.0.0.0/8 [90/3196416] via 1.1.1.2, 00:01:36, Serial4/0
D     192.168.2.0/24 [90/2297856] via 1.1.1.2, 00:02:47, Serial4/0
D     192.168.3.0/24 [90/2809856] via 1.1.1.2, 00:01:54, Serial4/0
D     192.168.4.0/24 [90/3321856] via 1.1.1.2, 00:01:31, Serial4/0


R2#show eigrp protocols
EIGRP-IPv4 Protocol for AS(65100)
  Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  NSF-aware route hold timer is 240
  Router-ID: 192.168.2.2
  Topology : 0 (base)
    Active Timer: 3 min
    Distance: internal 90 external 170
    Maximum path: 4
    Maximum hopcount 100
    Maximum metric variance 1

R2#show ip route eigrp
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

D     3.0.0.0/8 [90/2681856] via 2.2.2.2, 00:01:48, Serial4/1
D     10.0.0.0/8 [90/2172416] via 1.1.1.1, 00:02:47, Serial4/0
D     30.0.0.0/8 [90/2172416] via 2.2.2.2, 00:01:53, Serial4/1
D     40.0.0.0/8 [90/2684416] via 2.2.2.2, 00:01:22, Serial4/1
D     192.168.1.0/24 [90/2297856] via 1.1.1.1, 00:02:47, Serial4/0
D     192.168.3.0/24 [90/2297856] via 2.2.2.2, 00:01:43, Serial4/1
D     192.168.4.0/24 [90/2809856] via 2.2.2.2, 00:01:17, Serial4/1

R3#show eigrp protocols
EIGRP-IPv4 Protocol for AS(65100)
  Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  NSF-aware route hold timer is 240
  Router-ID: 192.168.3.3
  Topology : 0 (base)
    Active Timer: 3 min
    Distance: internal 90 external 170
    Maximum path: 4
    Maximum hopcount 100
    Maximum metric variance 1

R3#show ip ei
R3#show ip eigrp route
                 ^
% Invalid input detected at '^' marker.

R3#show ip route ei
R3#show ip route eigrp
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

D     1.0.0.0/8 [90/2681856] via 2.2.2.1, 00:01:30, Serial4/1
D     10.0.0.0/8 [90/2684416] via 2.2.2.1, 00:01:30, Serial4/1
D     20.0.0.0/8 [90/2172416] via 2.2.2.1, 00:01:30, Serial4/1
D     40.0.0.0/8 [90/2172416] via 3.3.3.3, 00:01:00, Serial4/2
D     192.168.1.0/24 [90/2809856] via 2.2.2.1, 00:01:30, Serial4/1
D     192.168.2.0/24 [90/2297856] via 2.2.2.1, 00:01:30, Serial4/1
D     192.168.4.0/24 [90/2297856] via 3.3.3.3, 00:00:54, Serial4/2



R4#show eigrp protocols
EIGRP-IPv4 Protocol for AS(65100)
  Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  NSF-aware route hold timer is 240
  Router-ID: 192.168.4.4
  Topology : 0 (base)
    Active Timer: 3 min
    Distance: internal 90 external 170
    Maximum path: 4
    Maximum hopcount 100
    Maximum metric variance 1

R4#show ip route ei
R4#show ip route eigrp
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

D     1.0.0.0/8 [90/3193856] via 3.3.3.2, 00:00:39, Serial4/2
D     2.0.0.0/8 [90/2681856] via 3.3.3.2, 00:00:39, Serial4/2
D     10.0.0.0/8 [90/3196416] via 3.3.3.2, 00:00:39, Serial4/2
D     20.0.0.0/8 [90/2684416] via 3.3.3.2, 00:00:39, Serial4/2
D     30.0.0.0/8 [90/2172416] via 3.3.3.2, 00:00:39, Serial4/2
D     192.168.1.0/24 [90/3321856] via 3.3.3.2, 00:00:39, Serial4/2
D     192.168.2.0/24 [90/2809856] via 3.3.3.2, 00:00:39, Serial4/2
D     192.168.3.0/24 [90/2297856] via 3.3.3.2, 00:00:39, Serial4/2


R3#show clock
*13:05:18.351 UTC Fri Feb 11 2022

R3#clock set 15:15:15 25 july 2020

*Jul 25 15:15:15.000: %SYS-6-CLOCKUPDATE: System clock has been updated from 13:06:12 UTC Fri Feb 11 2022 to 15:15:15 UTC Sat Jul 25 2020, configured from console by console.

R3#show clock

15:15:23.199 UTC Sat Jul 25 2020


R3(config)#NTP master 8
R3(config)#exit

R3(config)#ntp source loopback 0

R3(config)#ntp server 192.168.3.3

R1#show clock

*13:14:36.687 UTC Fri Feb 11 2022

R1#show clock

*13:14:39.259 UTC Fri Feb 11 2022

R1(config)#ntp server 192.168.3.3
R1(config)#exit


R1#show clock
*15:23:34.069 UTC Sat Jul 25 2020


R2#show clock
*13:13:01.619 UTC Fri Feb 11 2022

R2(config)#ntp server 192.168.3.3
R2(config)#exit

R2#show clock
*15:24:01.200 UTC Sat Jul 25 2020


R4#show clock
*13:14:40.535 UTC Fri Feb 11 2022

R4(config)#ntp server 192.168.3.3
R4(config)#exit

R4#show clock
15:24:56.677 UTC Sat Jul 25 2020

R3#show ntp packets
Ntp In packets                  :  27
Ntp Out packets                 :  36
Ntp bad version packets         :  0
Ntp protocol error packets      :  0



R3#show ntp status
Clock is synchronized, stratum 8, reference is 127.127.1.1
nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**18
ntp uptime is 55200 (1/100 of seconds), resolution is 4000
reference time is E2C6CD63.0A3E5987 (15:25:23.040 UTC Sat Jul 25 2020)
clock offset is 0.0000 msec, root delay is 0.00 msec
root dispersion is 0.35 msec, peer dispersion is 0.23 msec
loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000000000 s/s
system poll interval is 16, last update was 8 sec ago.


R3#show ntp associations

  address         ref clock       st   when   poll reach  delay  offset   disp
*~127.127.1.1     .LOCL.           7     14     16   377  0.000   0.000  0.235
 ~192.168.3.3     .INIT.          16      -     64     0  0.000   0.000 15937.
 * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured




 


 


Instagram

Facebook


Twitter



LINKEDIN








What is ASA firewall? How to configure Adaptive Security Appliance?

Introduction to firewalls The firewall is a barrier between LAN and WAN networks (trusted and untrusted networks), we configure the firewall...