Lab Setup

  • Make the connection as per the topology diagram above.
  • Use the IP addressing chart below to assign IP address to the routers.
  • All three routers are configured with RIPv2. And can ping each other.

IP Addressing Schema

Router

Interface

IP Address

R1

S0/0

100.1.12.1/24

Loop0

1.1.1.1/24

R2

S0/0

100.1.12.2/24

 

S0/1

100.1.23.2/24

 

Loop0

2.2.2.2/24

R3

S0/0

100.1.23.3/24

 

Loop0

3.3.3.3/24

 

Lab Objectives

  1. Configure R2, that only allows for the following traffic through the S0/1(Outside Network) interface:
  • SMTP traffic that originates from the inside networks.
  • Only Java applets from network 1.1.1.0 /24 should be down loaded. Ensure that audit trail logging and real time alerts are enabled for this inspection.
  • Allows Net-Meeting traffic that originates from the inside networks.
  • Allowing routing traffic for RIPv2 and ICMP should function properly.

R2 Configuration

R2(config)#access-list 1 permit 1.1.1.0 0.0.0.255

R2(config)#access-list 100 permit icmp any any

R2(config)#access-list 100 permit udp any any eq rip

R2(config)#ip inspect name FIREWALL http java-list 1 alert on audit-trail on

R2(config)#ip inspect name FIREWALL smtp

R2(config)#ip inspect name FIREWALL h323 (Note: – h323 protocol is used for MS NetMeeting, Intel Video Phone)

R2(config)#int s0/1

R2(config-if)#ip inspect FIREWALL out

R2(config-if)#ip access-group 100 in

Key Points to Remember

  • The access-list for the Java applets must be standard.
  • If the access-list does not exist, all Java applets from all address will be blocked.
  • IOS Firewall does not detect or block encapsulated Java applets such as applets in “.zip” format.
  • IOS Firewall does not detect or block applets loaded via FTP, Gopher or HTTP on a non-standard port.

Verification

R2#show ip inspect all

Session audit trail is disabled

Session alert is enabled

one-minute (sampling period) thresholds are

[unlimited : unlimited] connections

max-incomplete sessions thresholds are [unlimited : unlimited]

max-incomplete tcp connections per host is unlimited. Block-time 0 minute.

tcp synwait-time is 30 sec — tcp finwait-time is 5 sec

tcp idle-time is 3600 sec — udp idle-time is 30 sec

tcp reassembly queue length 16; timeout 5 sec; memory-limit 1024 kilo bytes

dns-timeout is 5 sec

Inspection Rule Configuration

Inspection name FIREWALL

http java-list 1 alert is on audit-trail is on timeout 3600

smtp max-data 20000000 alert is on audit-trail is off timeout 3600

h323 alert is on audit-trail is off timeout 3600

Interface Configuration

Interface Serial0/1

Inbound inspection rule is not set

Outgoing inspection rule is FIREWALL

http java-list 1 alert is on audit-trail is on timeout 3600

smtp max-data 20000000 alert is on audit-trail is off timeout 3600

h323 alert is on audit-trail is off timeout 3600

Inbound access list is 100

Outgoing access list is not set

R2#show ip inspect statistics

Interfaces configured for inspection 1

Session creations since subsystem startup or last reset 0

Current session counts (estab/half-open/terminating) [0:0:0]

Maxever session counts (estab/half-open/terminating) [0:0:0]

Last session created never

Last statistic reset never

Last session creation rate 0

Maxever session creation rate 0

Last half-open session total 0

TCP reassembly statistics

received 0 packets out-of-order; dropped 0

peak memory usage 0 KB; current usage: 0 KB

peak queue length 0