cdp disclosure

Fault symptomI have participated in a cabling project where one CISCO 4006 trunk switch is used as a route between VLANs. In addition, there are more than 10 C1SCO 2924 desktop switches and one CISCO 3640 egress router.The CISCO works 4.0 LAN Solution software suite (LMS 2000) is installed on a Windows NT 2.0 + IE5.5 computer ), however, when you view the network Topology in the Campus Manager Topology Serverices Layer2view, you can only see one CISCO 2924 switch, a CISCO 4006 switch, and a CISC

Hardware and Software Versions This configuration is applicable to all Cisco IOS software versions. DCE edge is connected by Wan DCE cable. DTE edge is connected by Wan DTE cable. For more information about the wan dce/DTE cable, see the serial cable documentation.Network Diagram 650) this. width = 650; "src =" 51cto.com/uploads/allianz 110909/1212454314-0.jpg "border =" 0 "/> This article is based on the following Configuration: In this configuration, Prasit serves as DCE and Spicey as DTE. Co

learned. However, this method may cause network topology information leakage. It may also disrupt the routing information table that works normally on the network by sending its own routing information table to the network. In severe cases, the entire network may be paralyzed. The solution to this problem is to authenticate the route information exchanged between routers in the network. When the router is configured with an authentication method, it will identify the sender and receiver of the

SNMP Trap is a protocol function in the SNMP protocol. In many devices, we use this self-trapping function for some management. So let's talk about some SNMP Traps in Cisco today. Configure a Cisco IOS device In the Enable status of IOS, click config terminal to enter the global configuration status. Enable Cdp run Snmp-server community gsunion ro Configure the read-only string of this vro as gsunion Snmp-server community gsunion rw Configu

There are three switch modes: storage forwarding, fast forwarding, and segmented forwarding.1. CSMA/CD (Multi-Channel Access for carrier listeners with conflict detection)Working principle: Listen to whether the channel is idle before sending. If it is idle, send it immediately. When sending the message, listen to it. If there is a conflict, immediately stop sending and wait for a random period of time, resend.2. CDP: When a cisco device is started,

Co-processorThe coprocessor is used to perform specific processing tasks, such as: The math coprocessor can control digital processing to reduce the burden on the processor. ARM can support up to 16 coprocessors, where CP15 is the most important one.CP15 provides 16 sets of registersAccess CP15 by providing 16 sets of registersOne, coprocessor accessARM microprocessors can support up to 16 coprocessors for various coprocessor operations, and during program execution, each coprocessor executes on

1. Basic router inspection commands Show version Show Processes Show protocols Show mem Show IP Route Show startup-config Show running-config Show flash Show interfaces Ii. Basic route configuration commands Enter: config Terminal/memory/Network Frequently Used commands for network configuration: Copy and Load 1. ID: Hostname 2. startup ID: banner startup ID 3. Interface: interface port number 4. Password: line 0 6 Login Passwd Password Enable password/secret password 5. interface: 1) configure

) displays relay information (mode, encapsulation, allow port, trim 、... ）Show interface trunk; (IOS)Show Spantree (CatOS) Displays the STP mode, type, status, and speed port of the port 、... ）Show Spanning-tree; (IOS)3. Discover information about neighboring Cisco devicesCDP (Cisco Discovery Protocol) is a proprietary protocol for Cisco that identifies directly adjacent Cisco device information, and CDP works on the 2nd tier.Show

FastEthernet0/0ip address 192.168.23.1 255.255.255.0ip verify unicast reverse-pathip nat insideip route-cache same-interfaceip route-cache policyduplex autospeed autono cdp enable! Interface Serial0/0 bandwidth 2048ip address specified parameter 255.255.252ip verify unicast reverse-pathno ip proxy-arpip nat outsiderate-limit input 2000000 20000 20000 conform-action transmit exceed-action dropip route-cache policyservice-policy output qos_policy_mapno

not encrypted during network transmission, strict control is required. For example, set a strong password, control the number of concurrent connections, strictly control the access address using the access list, and set user access control using AAA.8. We recommend that you use FTP instead of TFTP for iOS upgrade and backup and configuration file backup. For example:Router (config) # ip ftp Username blushinRouter (config) # ip ftp password 4tppa55w0rdRouter # copy startup-config ftp:9. Upgrade

: • Traffic and Protocol ACLs or filters • QoS tags and priority levels (control protocols are differentiated by corresponding service levels or DSCP values) • Selectively disable Layer 2 protocols on untrusted ports (for example, disabling DTP on access ports) • Configure the in-band Management port only on the dedicated VLAN • Avoid using VLAN 1 to transmit any data traffic Command example: Catalyst Operating System (CatOS) software Cisco IOS o Software UseVLAN 1Precautions The reason why VL

Background: 1. The relationship between the IP address and the MAC address in the ARP table of the layer-3 device. 2. the forwarding bridge table of the L2 device stores the correspondence between MAC and forwarding ports. 3. CDP (Cisco Discovery Protocol) is the link layer protocol for discovering adjacent devices between Cisco devices. 4. The forwarding table in the layer-2 module of a layer-3 switch is implemented in a cam table, such as sh

1. disable CDP (Cisco Discovery Protocol ). For example: Router (config) # No CDP run Router (config-If) # No CDP enable 2. Disable other TCP and UDP small services. Router (config) # No service TCP-small-servers Router (config) # No service UDP-Samll-servers 3. Disable the Finger service. Router (config) # No IP finger Router (config) # No servic

connections, use Access list to strictly control access to the address, you can use AAA to set User access control. 8,ios upgrades and backups, as well as backup of configuration files suggest using FTP instead of TFTP. Such as: Router (Config) #ip FTP username Blushin Router (Config) #ip ftp password 4tppa55w0rd Router#copy startup-config ftp: 9, timely upgrade and repair the iOS software. Second, the security configuration of router "Network Service" 1, the

. 4. Prevent viewing of router diagnostic information. Close the command as follows: No service tcp-small-servers no service udp-small-servers 5. Block the current list of users from viewing the router. The Turn off command is: no service finger. 6. Turn off CDP services. On the basis of the OSI two-layer protocol, which is the link layer, some configuration information of the End-to-end router can be found: device platform, operating system ver

FTP instead of TFTP. Such as: Router (Config) #ip FTP username Blushin Router (Config) #ip ftp password 4tppa55w0rd Router#copy startup-config ftp: 9, timely upgrade and repair the iOS software. [Page] Second, the Router Network Service security Configuration 1, the CDP (Cisco Discovery Protocol) is prohibited. Such as: Router (Config) #no CDP run Router (CONFIG-IF) # no

. Upgrade and patch IOS software in a timely manner.Ii. vro Network Service Security Configuration1. disable CDP (Cisco Discovery Protocol ). For example:Router (Config) # no cdp runRouter (Config-if) # no cdp enable2. Disable other TCP and UDP Small services.Router (Config) # no service tcp-small-serversRouter (Config) # no service udp-samll-servers3. Disable th

power failure, the system implements the "password repair process" and then logs on to the vro to completely control the vro. 3. Protect the vro password. In the vro configuration file backed up, even if the password is stored in encrypted form, the plaintext of the password may still be cracked. Once the password is leaked, the network is completely insecure. 4. Check the router diagnostic information. The command to disable the service is as follows: no service tcp-small-servers no service ud

username BluShinRouter (Config) # ip ftp password 4tppa55w0rdRouter # copy startup-config ftp: 9. promptly upgrade and patch IOS software. Ii. vro Network Service Security Settings 1. disable CDP (Cisco Discovery Protocol ). For example, Router (Config) # no cdp run Router (Config-if) # no cdp enable www.2cto.com 2. Disable other TCP and UDP Small services. Rout

: fastEthernet0/0 Secur Ing Management plane services... disabling service authentication service padDisabling udp tcp small serversEnabling service password Authentication service tcp-keepalives-inEnabling service tcp-keepalives-outDisabling the cdp beyond the bootp serverDisabling the http serverDisabling the finger has source already reached arpHere is a sample Security Banner To be shownat every access to device. modify it to suit yourenterprise