Friday, January 6, 2012

Turning Off unwanted Services in Cisco Routers

General Services
Now we will disable Cisco Discover Protocol at layer 2.
router1#config t
router1(config)# no cdp run

Now we will disable tcp and udp small servers
router1(config)# no service tcp-small-servers
router1(config)# no service udp-small-servers

Now we will disable Finger service
router1(config)# no ip finger
router1(config)# no service finger

Now we will disable HTTP Server
router1(config)# no ip http server

Now we will disable bootp server to prevent other system booting over network
router1(config)# noip bootp server

Now we will disable SNMP
router1(config)# no snmp-server community public RO
router1(config)# no snmp-server community private TW
router1(config)# no snmp-server enable traps
router1(config)# no snmp-server system-shutdown
router1(config)# no snmp-server trap-auth
router1(config)# no snmp-server

Now we will disable DNS lookup to broadcast addresses
router1(config)# no ip domain-lookup

Now we will disable Auto Loading
router1(config)# no boot network
router1(config)# no service config

Now we will disable IP source Routing
router1(config)# no  ip source-route

Now we will see about disabling Interface services

Now we will disable IP Directed Broadcast
router1(config)# interface eth1
router1(config-if)# no ip directed-broadcast

Now we will disable ICMP
router1(config)# interface eth1
router1(config-if)# no ip redirect

router1(config-if)# no ip unreachable
router1(config-if)# no ip mask-reply
router1(config-if)# end

Now we will disable Address Resolution Protocol over different LAN.
router1(config)# no  ip proxy-arp

Now we will disable NTP
router1(config)#access-list 101 deny [ntp|tcp] any any eq 123
router1(config)#interface eth1
router(config-if)#ip access-group 101 in
router(config-if)#ntp disble
Now we will disable unused Interfaces
router1#config t
router1(config)#interface eth2


  1. A very helpful article I must say, for an avergae joe like me who just know some basics of networking this will help a lot in tweaking our companies router to our needs now, Though I am thinking of calling in the experts from our Cisco SMARTnet providers to help me setup the things, lets see if I can do things on my own or mess up :-)

  2. Cisco routers are certainly worth the purchase and you should definitely think about it if you have a small or even large business. Cisco routers don't have to be complicated so you shouldn't avoid them if you're worried about the technical part - they will help you in the long run.

    Configure netflow on a cisco router