Cisco commands you didnt know that you needed to know.

I wanted to start a thread to see what cool commands are out there that you use that is not a well known command.

I will start with my 3 favorites!

Router#who

Router#show cry ses
"Shows vpn session"

Router#test interfaces

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theodoxa

# show ip ospf rib

It lists any tags that have been applied to an OSPF route and if that route has been installed in the routing table or not.

linuxabuser

clear interface

to bounce (stop/restart) an interface.

Hondabuff

Router#clear ip dhcp binding *

Clears all DHCP addresses.

d4nz1g

archive - found this while looking for an automated config backup solution lol

RouteMyPacket

I know every single config command ever:

?

networker050184

But what about the hidden commands?!

Hondabuff

Router#wr
Building configuration...
[OK]

and

R1#test crash
WARNING: Command selections marked with '(crash router)' will crash
router when issued. However a selection 'C' will need to
be issued IMMEDIATELY before these selections to enable them.

Type the number for the selected crash:

1 (crash router) Bus Error, due to invalid address access
2 (crash router) Bus Error, due to parity error in Main memory
3 (crash router) Bus Error, due to parity error in I/O memory
4 (crash router) Address Error, due to fetching code from odd address
5 (crash router) Jump to zero
6 (crash router) Software forced crash
7 (crash router) Illegal read of address zero
8 (crash router) Divide by zero
9 (crash router) Corrupt memory
C Enable crash router selection marked with (crash router)
R (crash router) User enter read bus error address
U (crash router) User enter write bus error address
W (crash router) Software watchdog timeout (*** Watch Dog Timeout ***)
w (crash router) Process watchdog timeout (SYS-2-WATCHDOG)
d Disable crashinfo collection
e Enable crashinfo collection
i Display contents of current crashinfo flash file
m Write crashinfo on crashinfo RAM
n Change crashinfo flash file name
q Exit crash menu
s Save crashinfo to current crashinfo flash file
c Close current crashinfo flash file
t Write crashinfo on console TTY
x Exit crash menu

Legacy User

#more system:running-config

-Used for finding the Site to Site preshared key

xnx

theodoxa wrote: »

# show ip ospf rib

It lists any tags that have been applied to an OSPF route and if that route has been installed in the routing table or not.

I learnt this one recently too

gorebrush

test crash? Hohoo going to try that one

RouteMyPacket

dmarcisco wrote: »

#more system:running-config

-Used for finding the Site to Site preshared key

On the ASA platform only

aaron0011

debug capwap console cli is required first before you can run the archive command on a CAPWAP to upgrade the IOS. The version on this particular AP wouldn't register to the vWLC. Pretty obscure but good one to know if you work with wireless at all.

JeanM

#csim start is my fave while learning voice stuff discovered it .

Cisco CSIM (Call Simulation) – Hidden IOS Command « Mark Holloway

Legacy User

JeanM wrote: »

#csim start is my fave while learning voice stuff discovered it .

Cisco CSIM (Call Simulation) – Hidden IOS Command « Mark Holloway

I wonder if that that cmd is really used in a live setting? When I came across it some time ago I read somewhere its undocumented because when people used that cmd it crashed there routers.

aquilla

dmarcisco wrote: »

I wonder if that that cmd is really used in a live setting? When I came across it some time ago I read somewhere its undocumented because when people used that cmd it crashed there routers.

I used this command a while back. Simulated the call successfully then the router stopped responding

As you say, that command crashed the router and forced it reload. Not really what I wanted in the middle of a nightshift with the router a couple of hundred miles away.

aquilla

BGP backdoor - Came across this the other day.

Cisco IOS IP Routing: BGP Command Reference - BGP Commands: neighbor timers through show bgp nsap summary [Support] - Cisco

Legacy User

aquilla wrote: »

I used this command a while back. Simulated the call successfully then the router stopped responding

As you say, that command crashed the router and forced it reload. Not really what I wanted in the middle of a nightshift with the router a couple of hundred miles away.

Well now i'm definitely not ever going to use that cmd lol.

JeanM

Well, it works in a lab and haven't crashed once yet

theodoxa

I got a little dyslexic and discovered a new command

# show ip ospf route

stlsmoore

show ip route longer-prefixes

Hondabuff

Another cool command some of you might know is the auto state command. I had to add another VLAN to router at our Stanford site and our field tech wasn't plugging anything in until Monday. Normally the SVI will not ping through the VPN but toss on the no auto state command on the VLAN and viola! Ping away with nothing plugged into it.