During baselining or troubleshooting activity you may need to determine out the CPU Utilization of your device. The following command show the 5 second, 1 minute, and 5 minute CPU Utilization of your device, and what processes are using the cpu.
This command works on all Cisco IOS devices I’ve ever configured.
This is for you folks that have an old 2900XL switch. So old that you need to troubleshoot, but you’ve forgotten the password to get in.
This was tested on 12.05 code.
1) Hold the "Mode" button while connecting the power cord (careful, electric current running through your body is very panful from what I’ve heard).
2) I let go of the button after 15 or 20 seconds, but there is an official number of seconds (see CCO at http://www.cisco.com).
3) You’ll be be dropped at the "switch:" prompt.
4) Type "flash_init" and press enter.
5) Type "load_helper" and press enter.
6) Type "rename flash:config.text flash:config.old" (or .new, or whatever you like that’s different from the original name 
) and press enter.
7) Type "boot" and press enter.
8) When the switch boots up type "no" and press enter to bypass setup.
9) Press "Enter"
10) Type "rename flash:config.old flash:config.text" and press enter.
11) Type "copy flash:config.text system:running-config" and press enter.
12) Press "Enter".
13) Now you will be back to your old configuration.
Don’t forget to change you passwords to something you know, or you’ll be doing this all over again!
In the following commands quotes are only used for illustration. They should not be typed as part of the command.
**Note – the actual username and password you want to configure should be typed in the command instead of ‘theusername’ and ‘thepassword’.
This is a basic tasks that Network folks and SysAdmins who are responsible for their own LANs will find useful. This how to requires basic knowledge of vlans and trunks.
BTW, Nortel folks use the term "tagging" instead of "trunking."
If you’re not familiar with with those concepts http://www.cisco.com is a good place to search. Use the keywords trunking and vlans in your search.
***Note – 802.1q is the standard and should be used especially if you are going to connect the other end of the trunk to a non-Cisco switch.
You’ve now configured the port as an 802.1Q trunk that will tag traffic from all the vlans except VLAN1 (VLAN1 is Cisco’s default Native VLAN) as they exit the port.
This is the most commonly used method of restricting Telnet access to Cisco IOS-based Routers and Switches.
Only after a successful login should you go to the next step!
How to configure an Extended Access List on Cisco Routers and IOS based Switches
Securing devices such as routers and switches from unauthorized access, restricting access between hosts or networks, protecting the perimeter of your network, and setting up IPSec tunnels are some of the tasks that require an understanding of access lists.
This short How To will show you how to configure an extended access list entry. The extended access list differs from standard access list in allowing you to configure source and destination IP Addresses, Source and Destination ports, and other parameters – including the times the access list is in effect (a very cool feature, in my opininion)!
This access list entry will be configured to allow the 192.168.1.0/24 network to send packets to the 10.1.1.0/24 network via IP. It will also log packets that match the access list, allowing you to determine whether traffic is flowing
from the 192.168.1.0/24 network to the 10.1.1.0/24 network.
***Note – the access entry is one way. If there is an access list configured on the return path, the source and destination networks in the access list entry below should be reversed and configured in that access list.
***Note – because there is only one entry in the access list the 192.168.1.0/24 network will only be allowed to send packets to the 10.1.1.0/24 network. This is because in a Cisco access-list only traffic that is explicitly allowed will be passed through.
***Note – check your Cisco IOS device to see if sending Netflow is supported. I was surprised to find that some Cisco layer 3 switching platforms don’t currently support Netflow. An example is the Catalyst 3560.
In Global configuration mode:
Under the interfaces you want to get statistics on:
This configuration is specific to non-MLS devices. There will be an MLS specific Netflow HowTo shortly.
**Note** – once you complete this procedure the startup configuration is gone from the IOS device. If you have not stored the configuration somewhere it’s lost for good!`
Now you can create a new configuration and it will be recognized if the IOS device is restarted.
This quick how to is for those linux admin/users who have there Linux server accessible to the outside world.
Don’t you hate when those bots start hitting you with a ssh dictionary attack??? Well block using IPTABLES.
I will try to make this tutorial as general as possible, as I can give you the REDHAT way of doing things as concerns to where REDHAT base systems maintain there networking files or Gentoo based systems…etc
sabayon-dynasty ~ # ifconfig
eth0
Link encap:Ethernet HWaddr 00:0E:35:94:FB:D9
inet addr:192.168.101.5 Bcast:192.168.101.255 Mask:255.255.255.0
inet6 addr: fe80::20e:35ff:fe94:fbd9/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2656195 errors:0 dropped:19 overruns:0 frame:0
TX packets:1762149 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3593125256 (3426.6 Mb) TX bytes:144856589 (138.1 Mb)
Interrupt:10 Base address:0xe000 Memory:e0200000-e0200fff
DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:E0:81:24:CQ:82
ONBOOT=yes
DEVICE=eth0
BROADCAST=192.168.101.255
BOOTPROTO=static
HWADDR=00:E0:81:24:CQ:82
IPADDR=192.168.101.5
NETMASK=255.255.255.0
NETWORK=192.168.101.0
ONBOOT=yes
TYPE=Ethernet
config_eth0=( "dhcp" )
dhcp_eth0="nosendhost"
dns_domain_eth0="linuxdynasty"
config_eth0=( "192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255" )
routes_eth0=("default via 192.168.0.1") # IPv4 default route