Configuring Cisco IOS Firewall IDS; Configuring VPNs. Each section includes a configuration example and verification steps, where available. This chapter describes how to configure the router using the CLI. Use the interface dot11radio global configuration CLI. Enters configuration mode for the dial backup interface. Step 2. dialerwatch-group group-number. Example: Router(config-if)#. DOWNLOAD YAHOO MESSENGER VN-ZOOM/F151
IP multicast switching Layer 2 interfaces LCP B LFQ B See LCP. LLC B See LFQ. MAC table manipulation RIP B See command modes. See also Easy IP Phase 1. NCP B See NAT. See NCP. PAP B See PAP. See PVC. See PPP. See IPCP. PPPoA, configuration example PPPoE client , ATM B PPP authentication B-3 to B See RIP. RST bits B RSVP B See G. Switch Switch Port Configurations Switch port configurations Switch Ports Configuration, Cisco TCP port numbers, currently assigned D-1 to D See also console download.
Timesaver, defined See UDP. VC B DHCP server configuration Easy VPN configuration VLAN configuration VPDN Skip to content Skip to search Skip to footer. Book Contents Book Contents. Find Matches in This Book. Log in to Save Content. PDF - Complete Book 2. Updated: February 18, Perform the following tasks to configure this network scenario:. Perform these steps to create access lists for use by the firewall, beginning in global configuration mode:.
Creates an access list which prevents Internet- initiated traffic from reaching the local inside network of the router, and which compares source and destination ports. Creates an access list that allows network traffic to pass freely between the corporate network and the local networks through the configured VPN tunnel. Perform these steps to configure firewall inspection rules for all TCP and UDP traffic, as well as specific application protocols as defined by the security policy, beginning in global configuration mode:.
Defines an inspection rule for a particular protocol. Repeat this command for each inspection rule that you wish to use. Perform these steps to apply the ACLs and inspection rules to the network interfaces, beginning in global configuration mode:. Enters interface configuration mode for the inside network interface on your router. Assigns the set of firewall inspection rules to the inside interface on the router. Enters interface configuration mode for the outside network interface on your router.
Assigns the defined ACLs to the outside interface on the router. A telecommuter is granted secure access to a corporate network, using IPSec tunneling. Security to the home network is accomplished through firewall inspection.
There are no servers on the home network; therefore, no traffic is allowed that is initiated from outside. The following configuration example shows a portion of the configuration file for the simple firewall scenario described in the preceding sections. Skip to content Skip to search Skip to footer. Book Contents Book Contents. Find Matches in This Book. Log in to Save Content. PDF - Complete Book 2. Updated: February 19, Chapter: Configuring a Simple Firewall.
Configuring a Simple Firewall. Configure Access Lists Perform these steps to create access lists for use by the firewall, beginning in global configuration mode: Command.
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EIGRP ATM interface Easy VPN Fast Ethernet interface , GRE tunnel IKE policy IPSec tunnel NAT RIP VLANs VPNs , WAN interfaces IP address assignment DSL signaling protocol See DHCP. See also examples. Enhanced Interior Gateway Routing Protocol.
Ethernet B See access lists. IGMP snooping PPP B Internet connection, setting up IPCP B IP multicast switching Layer 2 interfaces LCP B LFQ B See LCP. LLC B See LFQ. MAC table manipulation RIP B See command modes. See also Easy IP Phase 1.
NCP B See NAT. See NCP. PAP B See PAP. See PVC. See PPP. See IPCP. PPPoA, configuration example PPPoE client , ATM B PPP authentication B-3 to B PAP uses a two-way handshake to verify the passwords between routers. To illustrate how PAP works, imagine a network topology in which a remote office Cisco router is connected to a corporate office Cisco router.
After the PPP link is established, the remote office router repeatedly sends a configured username and password until the corporate office router accepts the authentication. CHAP uses a three-way handshake to verify passwords. To illustrate how CHAP works, imagine a network topology in which a remote office Cisco router is connected to a corporate office Cisco router. After the PPP link is established, the corporate office router sends a challenge message to the remote office router.
The remote office router responds with a variable value. The corporate office router checks the response against its own calculation of the value. If the values match, the corporate office router accepts the authentication. The authentication process can be repeated any time after the link is established. User passwords are administered in a central database rather than in individual routers. This section describes the network interface protocols that Cisco fixed-configuration routers support.
The following network interface protocols are supported:. Ethernet was designed to serve in networks with sporadic, occasionally heavy traffic requirements, and the IEEE A host wanting to send data waits until it detects no traffic before it transmits. Ethernet allows any host on the network to transmit whenever the network is quiet. A collision occurs when two hosts listen for traffic, hear none, and then transmit simultaneously. In this situation, both transmissions are damaged, and the hosts must retransmit at some later time.
Algorithms determine when the colliding hosts should retransmit. Asynchronous Transfer Mode ATM is a high-speed multiplexing and switching protocol that supports multiple traffic types, including voice, data, video, and imaging. ATM is composed of fixed-length cells that switch and multiplex all information for the network. An ATM connection is simply used to transfer bits of information to a destination router or host. Each ATM node must establish a separate connection to every node in the ATM network that it needs to communicate with.
All such connections are established through a permanent virtual circuit PVC. A PVC is a connection between remote hosts and routers. An AAL defines the conversion of user information into cells. An AAL segments upper-layer information into cells at the transmitter and reassembles the cells at the receiver.
Cisco series routers also support AAL1 and 2 formats. ATM e ncapsulation is the wrapping of data in a particular protocol header. Each PVC is considered a complete and separate link to a destination node. Users can encapsulate data as needed across the connection. The ATM network disregards the contents of the data. The only requirement is that data be sent to the ATM subsystem of the router in a manner that follows the specific AAL format.
Dialer interfaces can be configured independently of any physical interface and applied dynamically as needed. Dial backup provides protection against WAN downtime by allowing a user to configure a backup modem line connection. The following can be used to bring up the dial backup feature in Cisco IOS software:. A backup interface is an interface that stays idle until certain circumstances occur, such as WAN downtime, at which point it is activated.
The backup interface can be a physical interface such as a Basic Rate Interface BRI , or an assigned backup dialer interface to be used in a dialer pool. While the primary line is up, the backup interface is placed in standby mode. In standby mode, the backup interface is effectively shut down until it is enabled. Any route associated with the backup interface does not appear in the routing table. The interfaces to such connections go down when the primary line fails, and the backup interface quickly identifies such failures.
Floating static routes are static routes that have an administrative distance greater than the administrative distance of dynamic routes. Administrative distances can be configured on a static route so that the static route is less desirable than a dynamic route. In this manner, the static route is not used when the dynamic route is available. However, if the dynamic route is lost, the static route can take over, and the traffic can be sent through this alternative route. If this alternative route uses a dial-on-demand routing DDR interface, then that interface can be used as a backup feature.
Dialer watch is a backup feature that integrates dial backup with routing capabilities. Dialer watch provides reliable connectivity without having to define traffic of interest to trigger outgoing calls at the central router. Hence, dialer watch can be considered regular DDR with no requirement for traffic of interest. By configuring a set of watched routes that define the primary interface, you are able to monitor and track the status of the primary interface as watched routes are added and deleted.
When a watched route is deleted, dialer watch checks for at least one valid route for any of the IP addresses or networks being watched. If there is no valid route, the primary line is considered down and unusable. If there is a valid route for at least one of the watched IP networks defined and the route is pointing to an interface other than the backup interface configured for dialer watch, the primary link is considered up and dialer watch does not initiate the backup link.
Network Address Translation NAT provides a mechanism for a privately addressed network to access registered networks, such as the Internet, without requiring a registered subnet address. This mechanism eliminates the need for host renumbering and allows the same IP address range to be used in multiple intranets. NAT is configured on the router at the border of an inside network a network that uses nonregistered IP addresses and an outside network a network that uses a globally unique IP address; in this case, the Internet.
NAT translates the inside local addresses the nonregistered IP addresses assigned to hosts on the inside network into globally unique IP addresses before sending packets to the outside network. With NAT, the inside network continues to use its existing private or obsolete addresses. These addresses are converted into legal addresses before packets are forwarded onto the outside network. The translation function is compatible with standard routing; the feature is required only on the router connecting the inside network to the outside domain.
Translations can be static or dynamic. A static address translation establishes a one-to-one mapping between the inside network and the outside domain. Dynamic address translations are defined by describing the local addresses to be translated and the pool of addresses from which to allocate outside addresses.
Allocation occurs in numeric order, and multiple pools of contiguous address blocks can be defined. NAT eliminates the need to readdress all hosts that require external access, saving time and money. It also conserves addresses through application port-level multiplexing. In this type of configuration, relatively few external addresses are required to support many internal hosts, thus conserving IP addresses. Because the addressing scheme on the inside network may conflict with registered addresses already assigned within the Internet, NAT can support a separate address pool for overlapping networks and translate as appropriate.
This feature enables a Cisco router to automatically negotiate its own registered WAN interface IP address from a central server and to enable all remote hosts to access the Internet using this single registered IP address. The ability of multiple LAN devices to use the same globally unique IP address is known as overloading. DHCP allocates network addresses from a central pool on an as-needed basis.
DHCP is useful for assigning IP addresses to hosts connected to the network temporarily or for sharing a limited pool of IP addresses among a group of hosts that do not need permanent IP addresses. DHCP allows for increased automation and fewer network administration problems by:.
This section describes Quality of Service QoS parameters, including the following:. Primary goals of QoS include dedicated bandwidth, controlled jitter and latency required by some real-time and interactive traffic , and improved loss characteristics. QoS technologies provide the elemental building blocks for future business applications in campus, WAN, and service provider networks.
QoS must be configured throughout your network, not just on your router running VoIP, to improve voice network performance. Not all QoS techniques are appropriate for all network routers. Edge routers and backbone routers in your network do not necessarily perform the same operations; the QoS tasks they perform might differ as well. To configure your IP network for real-time voice traffic, you need to consider the functions of both edge and backbone routers in your network.
QoS software enables complex networks to control and predictably service a variety of networked applications and traffic types. Almost any network can take advantage of QoS for optimum efficiency, whether it is a small corporate network, an Internet service provider, or an enterprise network.
You can partition traffic in up to six classes of service using IP Precedence two others are reserved for internal network use. The queuing technologies throughout the network can then use this signal to expedite handling.
Features such as policy-based routing and committed access rate CAR can be used to set precedence based on extended access-list classification. This allows considerable flexibility for precedence assignment, including assignment by application or user, by destination and source subnet, and so on.
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