02-25-2002 01:57 PM - edited 03-01-2019 08:37 PM
I am a little new to cisco routers and need some assistance. I would like to know if it is possible and how to block SNMP at the router. If possible please step me through the actions I will need to perform.
Thanks in advance!
02-25-2002 06:22 PM
You block SNMP or any other IP traffic at the interface level by port number, SNMP is UDP port 161, so the command to block all SNMP traffic would be
access-list 101 deny udp any eq snmp any eq snmp
access-list 101 permit ip any any
You then apply this to the interfaces with the following command
ip access-group 101 in
See the following URL for more information on access lists
http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/secur_c/scprt3/scacls.htm
02-26-2002 05:51 AM
I am using a 2620 router.
I am in configure, then I enter the command "ip access-group 101 in" and get an error invalid input at... referencing group.
Any suggestions?
03-04-2002 10:38 AM
Hello,
Where are you are in the command modes. I think you are trying from GLOBAL configuration mode. Try it from INTERFACE configuration mode. That you can reach, let's assume for "Serial 0" then
1. conf t
2. int s0
3. ip access-group 101 in
Regards...
--Ashok.
03-04-2002 11:42 PM
ASHOK , if we just remove snmp communities, then is it enough?
03-06-2002 02:16 PM
Do you need to block SNMP from a single interface or all interfaces? Here is the command sequence:
Router>EN
Router#config t
Router(config)#ip access ex 101
Router(config-ext-nacl)#deny udp any any eq snmp
Router(config-ext-nacl)#deny udp any any eq snmptrap
Router(config-ext-nacl)#permit ip any any
now do a CTRL+Z
you should now be at this promt: Router#
Now verify your access list: sh ip acce
you should see your access list
---now to apply it to a interface----
Router#configt
Router(config)#int f1 ---or what ever interface ex. s0/0, e0/0, etc. etc.
Router(config-if)#ip acce 101 in --inbound to the interface, out is also a option if you do not want to broadcast these packets to the network segment of the attached interface..
Now do a CTRL+Z
you should now be at the Router# prompt
now type:
Router#copy run start
Destination filename [startup-config]? (just hit enter)
Building configuration...
[OK]
Now you are done, you can repeat appling the list to any other interface..
JD
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