Disable Telnet on Cisco Switch and Router

 1.    You must disable Telnet on your Cisco switch/router since it will be enabled by default and will not disable until you manually disable it.

2.    RTR-01>enable

3.    RTR-01#conf t

4.    RTR-01 (config) #line vty 0 15

5.    RTR-01 (config-line) #transport input ssh
    a.    This transport command is telling the switch/router to only accept SSH connections

6.    RTR-01 (config-line) #end

7.    RTR-01#write

Change SSH Version

1.    When you enable SSH, it might default to a version number that you are not running or do not wish to run. Make sure to enable the correct version.

2.    First, you can find out which version you are running by doing the following:
    a.    RTR-01>enable
    b.    RTR-01#show run | include ssh version
        i.    Here it will show you which version of SSH you are running
        ii.    You can also just type RTR-01#show ip ssh

3.    Next, you can change your version of SSH
    a.    RTR-01>enable
    b.    RTR-01#conf t
    c.    RTR-01 (config) #ip ssh version YOUR_DESIRED_VERSION
    d.    RTR-01 (config) #end
    e.    RTR-01#write
        i.    Or copy-running-config startup-config

4.    Now, verify your version number:
    a.    RTR-01#show ip ssh
    b.    Orr you can type: RTR-01#show run | include ssh version

Create User and Password for Cisco Device

1.    First, you will need to determine if you want a normal user, or an admin user. The following is for a normal user:
    a.    >enable
    b.    #conf t (configure terminal)
    c.    (config) #username YOUR_USER_NAME secret USER_PASSWORD

2.    If you wish to create an admin user, the following can be done”
    a.    >enable
    b.    #conf t
    c.    (config) #username YOUR_USER_NAME privilege 15 secret USER_PASSWORD

3.    Finally, you will need to enable logins into the switch/router by doing the following:
    a.    >enable
    b.    #conf t
    c.    (config) #enable secret DESIRED_PASSWORD_HERE
        i.    This will start requiring you to utilize logins into the switch and also with a default password
        into the switch too.

4.    You have now created a basic lockdown on your Cisco device. Again, this is just super basic utilizing the Cisco built in login local database.

5.    Which you can enable (if you have not already) this way:
    a.    For the console line:
    b.    >enable
    c.    #conf t
    d.    (config) #int line con 0
    e.    (config-line) #login local
    
    f.    And finally for your VTY lines:
    g.    >enable
    h.    #conf t
    i.    (config) #line vty 0 15
    j.    (config-line) #login local

6.    The main thing you need here is the login local command. This tells the switch/router to use the local user database to login.

Password Recovery for Old/Used Cisco Switch or Router

Sometimes you will obtain an old or used Cisco Switch or Router which has configurations on the device. You can still access the device if you don’t know the password. You can perform the following steps to recover the device all the while saving configurations too.

1.    Connect to the console port.
    a.    Ensure you have a console cable with the prolific device driver. Some cheaper console cables will not allow you to send the break signal during the router/switch boot process.

2.    Reboot the device and send a break signal within the first 30 seconds.
    a.    During reboot you have 30 seconds to send the break signal and interrupt the boot process. This is why you need a higher quality cable with the prolific device driver for break signals.
    b.    You are doing this to enter Rommon boot mode. To change were it looks for the startup configuration.
    c.    You have the following options for sending the break command since laptops and computers are all different:
        i.    Pause/Break key or Ctrl+Pause/Break on keyboard (This is usually the standard for regular keyboards)
        ii.    #Ctrl+Fn+F11
        iii.    #Fn+B
        iv.    #Ctrl+B
        v.    #Ctrl+Fn+B
    d.    Finally, PuTTY has an option to send the break command through the menus:
        i.    Under the PuTTY menu, hover over “Special Command”
        ii.    Then select the “Break” option there.

3.    Modify the Configuration register.
    a.    You are doing this in order to keep it from loading the previous configuration into the running-config. This allows us to bypass the password from the currently installed configuration.
    b.    In Rommon state, there is no OS loaded. It is for recovery purposes. We want to change the “confreg” setting. Type this in:
        i.    #confreg 0x2142
            1.    0x2142 puts it in a state of ignoring the VNRAM contents/startup configuration. But this keeps the old configuration in the system.
            2.    0X2102 is the normal state of boot. Makes it operate normally.
    c.    Next we reset the device to reboot with the new confreg code.
        i.    #reset

4.    Now you can recover your configuration in the router or switch and reset the passwords.
    a.    After reboot, you say “NO” to initial configuration dialog.
    b.    You are now in the router/switch without a configuration.
    c.    Your old configuration is in the startup-config. You can even do a:
        i.    #show startup-config
        ii.    And you can see your old configuration on the router/switch.
    d.    Now we can copy the startup-config into our running-config and we maintain admin rights without the old passwords blocking us:
        i.    #copy startup-config running-config
    e.    Also you can now reset your passwords in global config mode:
        i.    #conf t
        ii.    #enabled secret cisco
        iii.    #line con 0 password cisco
        iv.    And continue with others you wish to reset.
    f.    Make sure to save the configuration:
        i.    #write/#copy run start

5.    Revert the configuration register to the original boot so now you can load your configurations with the new password.
    a.    We have a final step to do. We will need to change that boot process again since that 0x2142 is not the normal boot state. We need to change it back to 0x2102.
        i.    #show version (shows the router/switch status and what the boot reg is set to)
        ii.    #conf t
        iii.    #config-register 0x2102
        iv.    #write
    b.    Now you can reboot with new passwords and your original configuration.

Wipe and Clear Configuration on Cisco Catalyst Router/Switch

This one is a simple one. We will be clearing out the configurations on Catalyst equipment. If you have a bunch of configurations you just want to clear so you can start from scratch, do the following:
1. Go to Privilege Mode
a. #enable
2. Erase the configuration:
a. #write erase
3. Restart the system:
a. #reload
b. #confirm (just hit enter here)

Reset the Password on Router without Losing the Old Configuration File

• Console cable needed on router
• Power off router
• Turn on router and issue the break command through Putty
• In rommon, hit question mark to see your options
o You should see confreg
• Change confreg to 0x2142
o >confreg 0x2142
• Reset the router
o >reset
• Once the router reboots, cancel the initial setup dialog. You just need the old startup-config
o >show startup-config
• Once you verify you see your old file, copy the old file to the running-config
o #copy startup-config running-config
• You are now in your old config file without the passwords. Now you can reset your password:
o #conf t
o #enable secret cisco
o #exit
o #copy run start
• Next, you need to change the configreg entry from when we changed it in ROMMON.
o #conf t
o #config-register 0x2102
o #exit
o #write
• Finally, you want to ensure your interfaces are all up since sometimes they go into admin down state and need to be brought up manually. You can reboot if necessary, but now you have access back into the router.

To Log into a Switch from Current Switch

1. You can perform this either from user mode or privileged mode:
a. SW1>ssh -l user_name ip_address
b. SW1#ssh -l user_name ip_address
2. After you pivot into the system from either of the above commands, type in the user’s password (the user you are using to log into the distant switch).

Configure Default Gateway on Cisco Switch

1. First, escalate into global configuration mode:
a. SW1(config)#Config Terminal
2. In global configuration mode you can now make a global setting indicating your default gateway for the switch:
a. SW1(config)#ip default-gateway ip_address

Configure Gateway of Last Resort

1. First, log into the switch you wish to configure.
2. Next, escalate up to Configure Terminal and then type the following:
    a. #conf t
    b.  #ip default-gateway 172.16.X.X
    c.  #end
    d.  #write
3. Next you can direct your traffic through this route if you wish, as a gateway of last resort:
    a. #ip route 0.0.0.0 0.0.0.0 172.16.X.X
    b. #end
    c. #write
4. Verify by typing in the following:
    a.  #show ip route
    b.  Then verify you see a gateway of last resort listed.


Reference:
https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/16448-default.html

Clearing UCSM error F0933 “named VLAN for vNIC cannot be resolved” errors

1.    First off upon logging onto your UCSM you find this lovely error:

2.    So what is happening here is you done messed up A A Ron! A VLAN was deleted from the global LAN Cloud area and more than likely is still attached to a vNIC template out there. There can be some other causes, but this has been the most common issue I have found with this error. Your UCS has a VLAN it does not know what to do with.
3.    So, from the error screen, go ahead and go to your LAN section in your UCS and go to your vNIC templates section:

4.    Now we can go ahead and select this VLAN we thought was gone, and click on the Delete at the bottom.

5.    Once you delete the VLAN, the errors should go down or start going away. You want to check all your vNIC templates to ensure it has been removed.