ROUTER COMMANDS (CISCO)

Routing is the act of moving information across an internetwork from a source to a destination. Along
the way, at least one intermediate node typically is encountered. Routing involves two basic activities: determining optimal routing paths and transporting information groups (typically called packets) through an inter network.

Router > enable

Router # configure terminal

Router(config) #

Router # show running-config

Router # show startup-config

Router # write

1. Hostname

Router(config) # hostname {name}

2. Set Password (to access Privileged Mode ) Router(config) # enable password {password}

Router(config) # enable secret {password}  à  Password is encrypted

3. IP Address

Router(config) # interface {interface} {interface_number}

                Router(config-if) # ip address  {ip-address} { mask}         

Router(config-if) # no shutdown à Turn on the interface

4. Telnet

Router(config)# line vty 0 4

Router(config-line)# login

Router(config-line)# password {password}

5. Enable Router to act as an HTTP server

Router (config)# ip http server

6. Set clock rate on DCE Serial interface 

Router# show controller serial {interface_number} à  check to find out whether the serial               interface is DCE or DTE.

Router(config) # interface {interface} {interface_number}

Router(config-if) #clock rate {clock}

7. Routing Protocols

*     Static

Router(config)# ip route {network} [mask] {address|interface} [distance][permanent]

distance metric for this route

*     RIP – Routing Information Protocol

Router(config) # router rip à Defines IP routing protocol.

Router(config-router) # network {network-number} à  specifies a directly connected network.

*     IGRP – Interior Gateway Routing Protocol

Router(config)# router igrp  autonomous-system

Router(config-router) # network {network-number}

*     EIGRP – Enhanced Interior Gateway Routing Protocol Router(config)# router eigrp  autonomous-system

Router(config-router) # network {network-number}

*     OSPF – Open Shortest Path First Protocol Router(config)# router ospf  process-id

Router(config-router)# network {address} {wildcard-mask}  area {area-id}

*     Show command

Router# show ip route

Router# show ip route w.x.y.z

Router# show ip protocols

Router# show ip {protocol} [ interface | database | neighbors | topology ]

Route Source	Default Distance
Connected interface	0
Static route	1
EIGRP summary route	5
External BGP	20
Internal EIGRP	90
IGRP	100
OSPF	110
IS-IS	115
RIP	120
EGP	140
EIGRP external route	170
Internal BGP	200
Unknown	255

8. Route Redistribute default−metric {bandwidth delay reliability loading mtu} : set metric value for all redistributed routes  (IGRP, EIGRP, OSPF, BGP, EGP).

9. Access Control Lists

Step 1 : Choose type of ACL ( Standard or Extended) and set parameters for the ACL test statements

§  Standard IP ACL

Router(config) # access-list access-list-number { permit | deny } source [mask]

Parameters	Description
access-list-number	Identifies the list that the entry belongs to; a number from 1 to 99
permit | deny	Indicates whether this entry allows or blocks traffic from the specified address
source	Identifies the source IP address
source [mask]	Identifies which bits in the address field are matched; default wildcard mask is 0.0.0.0 <host>

§  Extended IP ACL

Router(config) # access-list access-list-number { permit | deny } protocol source sourcewildcard [operator port] destination destination-wildcard [operator port] [established] [log]

Parameters	Description
access-list-number	Identifies the list using a number in the ranges of 100 to 199 or 2000 to 2699.
permit | deny	Indicates whether this entry allows or blocks traffic from the specified address
protocol	IP, TCP, UDP, ICMP, IGMP,..
source / destination	Identifies the source / destination IP addresses
source-wildcard destination-wildcard	Wildcard mask (0s : match, 1s : indicate “don’t care” positions )
operator  port	It(less than), gt (greater than), eq (equal), neq (not equal) and a port number.
established	For inbound TCP only, allows TCP traffic to pass if the packet uses an established connection. (Ex : it has ACK bits set )
log	Sends a logging message to the console

Step 2 : Enable an interface to use the specified ACL

Router(config) # ip access-group access-list-number { in | out }

Parameters	Description
access-list-number	Indicates number of ACL to be linked to this interface
in | out	Selects whether the ACL is applied as an incoming or outgoing filter; out is default.

Note : WILDCARD MASK

Address filtering occurs when you use ACL address wildcard masking to identify how to check or ignore corresponding IP address bits. Wildcard mask for IP address bits uses the number 1 and 0 to identify how to treat the corresponding IP address bits.

§  Wildcard mask bit 0 : Check the corresponding bit value in the address.

§  Wildcard mask bit 1 : Ignore (do not check) the corresponding bit value in the address.

Ex :  Host  : 172.30.16.29  à   Wildcard Mask : 0.0.0.0 ( host ) Subnet : 172.16.1.0   à   Wildcard Mask : 0.255.255.255.

All traffic : 0.0.0.0     à   Wildcard Mark : 255.255.255.255 ( any )

10. Network Address Translation

Private Addresses

Class	RFC 1918 Internal Address Range	CIDR Prefix
A	10.0.0.0 à 10.255.255.255	10.0.0.0/8
B	172.16.0.0 à 172.31.255.255	172.16.0.0/12
C	192.168.0.0 à 192.168.255.255	192.168.0.0/16

*   Step 1 : Configuring NAT

§  Static NAT - One Private to One Permanent Public Address Translation Router(config)#ip nat inside source static {local-ip} {global-ip}

§  Dynamic NAT - One Private to One Public Address Translation

Create an ACL that will identify which private IP addresses

Router(config) # access-list access-list-number  permit  source {mask}

Define a pool of usable public IP addresses

Router(config)#ip nat pool name {start-ip} {end-ip}  netmask { prefix-length} Link ACL to the pool of addresses.

Router(config)#ip nat inside source list {access-list-number | name} pool {name}

§  PAT - Many Private to One Public Address Translation Create an ACL that will identify which private IP addresses

Router(config) # access-list access-list-number { permit | deny } source [mask] Define a pool of usable public IP addresses

Router(config)# ip nat pool {name} {start-ip  end-ip}  netmask { prefix-length} Router(config)# ip nat pool {name} interface {interface-number} netmask { prefixlength}

Link ACL to the pool of addresses

Router(config)#ip nat inside source list {access-list-number | name} pool {name} overload

*   Step 2 :  Apply NAT on interface

§  Define the inside interface

Router(config)# interface {interface-number}

Router(config-if)# ip nat inside

§  Define the outside interface

Router(config)# int {interface-number}

Router(config-if)# ip nat outside

* Verifying - Troubleshooting NAT and PAT Configuration

Router#show ip nat translations   à Displays translation table

Router#show ip nat statistics   à Displays NAT statistics

Router#clear ip nat translations inside a.b.c.d outside e.f.g.h  à Clears a specific translation from the table before it times out

Router#clear ip nat translations *

Router#debug ip nat  à Displays information about every packet that is translated

Router#debug ip nat detailed

11. Enable SNMP (Simple Network Management Protocol)

Router(config) # snmp-server community snmp-community-string [acl | acl_name | ipv6 | ro | rw | view ]

<1-99>	Standard IP access list allowing access with this community string
<1300-1999>	Expanded IP access list allowing access with this community string
WORD	Access-list name
ipv6	Specify IPv6 Named Access-List
ro	Read-only access with this community string
rw	Read-write access with this community string
view	Restrict this community to a named MIB view

12. Netflow

 

§  Step 1 : Enabling NetFlow Export on interface

Router(config) # interface {interface} {interface_number}

Router(config-if) # ip route-cache flow

Router(config-if) # bandwidth <kbps>

§  Step 2 : Exporting NetFlow Data

Router(config) # ip flow-export source {interface} {interface_number}

Router(config) # ip flow-export destination {hostname| ip_address} {port}

Router(config) # ip flow-export version {netflow-version}

§  Step 3 : Verifying Device Configuration Router # show ip flow export

Router # show ip cache flow

Router # show ip cache verbose flow 

 

Reference : Commands Guide of Cisco