Cisco Systems EDCS-154011 manual Configuration Description

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Table 1: Two Interface PIX with NAT Configuration

Configuration

Description

 

 

nameif ethernet0 outside security0

PIX Firewall provides nameif and interface command

nameif ethernet1 inside security100

statements for the interfaces in the default configuration. Change

interface ethernet0 10baset

the default auto option in the interface command to the specific

interface ethernet1 10baset

line speed for the interface card.

Fixup protocol h323 1720

The fixup protocol commands let you view, change, enable, or

 

disable the use of a service or protocol through the PIX Firewall.

 

This command will show up in configuration by default.

ip address outside 209.165.201.5 255.255.255.224

Identify the IP addresses for both interfaces.

ip address inside 10.1.1.5 255.255.255.0

 

arp timeout 14400

Set the ARP timeout to 14,400 seconds (four hours). Entries are

 

kept in the ARP table for four hours before they are flushed.

nat (inside) 1 0 0

Permit all inside users to start outbound connections using the

 

translated IP addresses from the global pool.

global (outside) 1 209.165.201.10-209.165.201.30

Create a pool of global addresses for use when they exiting the

global (outside) 1 209.165.201.8

firewall from the protected networks to the unprotected

 

networks. The global command statement is associated with a

 

nat command statement by the NAT ID, which in this example is

 

1. Because there are limited IP addresses in the pool, a PAT (Port

 

Address Translation) global is added to handle overflow.

Route outside 0.0.0.0 0.0.0.0 209.165.201.1 1

Sets the outside default route to the router attached to the

 

Internet.

static (inside,outside) 209.165.201.10 10.1.1.10 netmask

The static command creates a permanent mapping (called a

255.255.255.255 0 0

static translation slot or "xlate") between a local IP address and a

static (inside,outside) 209.165.201.20 10.1.1.20 netmask

global IP address. Needed in a NAT environment to allow

255.255.255.255 0 0

inbound H.323 Calls.

static (inside,outside) 209.165.201.30 10.1.1.30 netmask

 

255.255.255.255 0 0

 

timeout xlate 3:00:00

Sets default values for the maximum duration that PIX Firewall

timeout conn 1:00:00 half-closed 0:10:00

resources can remain idle until being freed. Additional users

udp 0:02:00 rpc 0:10:00 h323 0:05:00

cannot make connections until a connection resource is freed

sip 0:30:00 sip_media 0:02:00

either by a user dropping a connection or by an xlate and conn

timeout uauth 0:05:00 absolute

timer time out.

access-list acl_out permit icmp any any

Allows inbound and outbound pings.

access-group acl_out in interrface outside

 

access-list acl_out permit udp any host 209.165.201.10

The access-list command lets you specify if an IP address is

eq 1719

permitted or denied access to a port or protocol. Port 1719 needs

access-list acl_out permit tcp any host 209.165.201.20

to be opened for Gatekeeper traffic, Port 2720 for the Cisco 3510

eq h323

MCU, and Port 1820 for the Cisco 3520/3525 Gateway.

access-list acl_out permit tcp any host 209.165.201.30

 

eq 2720

 

no snmp-server location

Specifies that SNMP information may be accessed by internal

no snmp-server contact

hosts that know the community string, but PIX Firewall does not

snmp-server community public

send trap information to any host.

telnet 10.0.0.100 255.255.255.255

Specifies that host 10.0.0.100 is permitted to access the PIX

telnet timeout 15

Firewall console via Telnet and that 15 minutes are allowed

 

before the idle timer runs out and the session is logged off.

mtu outside 1500

Sets the maximum transmission unit value for Ethernet access.

mtu inside 1500

 

Copyright © 2001 Cisco Systems, Inc.

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Contents An IP/VC Application Note Table of contents Introduction What is the Cisco Secure PIX Firewall? Issues with Firewalls and H.323Implementing NAT for use with in-bound H.323 traffic What is NAT?Two Interface PIX with NAT Diagram Configuration Description Static command Breaking down the PIX configuration Fixup protocol CommandAccess-list command Access-group aclID in interface interfacename Access-list aclout permit tcp any hostAccess-group aclout in interface outside Helpful Links Typical Ports used for H.323 traffic