Changing the hostname on CSS11500

First time I configured one of these it took me a while to figure out how to change the hostname.

Its easy once you know the answer but it is not found in configuration mode.

From enable mode you simply type the command prompt and then a name

e.g.

CSS11500# prompt my-css-01

Simple huh!

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Error Message %DUAL-6-NBRINFO: EIGRP-IPv4 34256

If you see the error %DUAL-6-NBRINFO: EIGRP-IPv4 xxxx is blocked: not on common subnet then it simply means that there are EIGRP devices sending multicast hellos on an interface which have a different IP Range configured to the receiving router. 160617: .Feb 22 15:11:05.194 GMT: %DUAL-6-NBRINFO: EIGRP-IPv4 34256: Neighbor 17 2.31.253.1 (Vlan43) is blocked: not on common subnet (172.31.252.1/31) 160618: .Feb 22 15:11:12.770 GMT: %DUAL-6-NBRINFO: EIGRP-IPv4 34256: Neighbor 19 2.168.205.0 (Vlan44) is blocked: not on common subnet (192.168.204.1/31) This is most likely to occur by accident when two subnets are configured on the same VLAN, with EIGRP running on the interface.

Moving the SSH port on a CISCO router

If you admin your routers over the internet you probably know you should be using SSH. Telnet being sent in clear text is easily sniffed and your passwords captured. However Cisco routers use the standard TCP port 22 for their SSH service. As soon as you open this up to the world and turn on SSH access logging you will start to see hundreds of IP's connecting to your device and running dictionary attacks against you using standard username and password combinations. The majority of these IP's seem to originate from China or Russia and they find your open port extremely quickly. This is very anoying it fills up your log files with these attacks and uses up your system resources dealing with them. I believe they are simply running scans for any open TCP port 22. For this reason I decided I could cut down the amount of attacks by moving the SSH port to a different number. One thing you should know before we start is that there is no way to actually change the SSH port number o

Shutting Cisco 3750 Stackwise ports

Today I came across a customers 3750 switch stack which had a flapping stackwise link. The stackwise link was transitioning up/down around 3 times a second and causing massive issues with connectivity and EIGRP routing for the site. Previously I believed that I would need to physically remove the Stackwise cable in order to restore service by shutting the flapping link. It seems it is possible to shut the Stackwise port from the CLI although it is done from enable mode rather than Configure terminal. The command is.. Switch#switch 1 stack port 1 ? disable Disable stack port enable Enable stack port The first number 1 would indicate the switch number in the stack and the second number 1 after the port is the Stackwise port number you want to shut. Make a note of which switch and port you shut as it will not show up in the config or the show outputs which could prove tricky when you want to reenable it.. You can determine the status of the ports using the command below but not how

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