Cisco notes 101

cdp timer   10  -> how often cdp packet transmited out all active interface.  (19sec)
cdp holdtime 5  -> amount time device wil hold packet received from neighbor address.  (5 sec)


no cdp run -> turn off cdp all interface
no cdp enable-> turn off cdp neihgboor on one interface
cdp enabl.



show cdp neighbor          -> show list devices directly connected neighbor
show cdp *                 -> show all directly connected information
show cdp * protocol        -> check directly connected device IP ADDRESS
show cdp entry * version   -> list all directly connected devices
show cdp traffic           -> check traffic!


show cdp interface         -> check interface status



from show running config we can get ip information!
from cdp neighbor we can mapping directly connected devices!


^ best tool for information gathering.
^ can create topology!




!! how to configure telnet !!

activate telnet on router:

- conf t
- line vty 0 807
- password telnet
- login
- ^Z




ctrl+shift6+x    ->  back to original router but keep session alive.
enter twice      ->  back to remote router ( after ctrl + shift +  6 )

#show session -> checking session ( who logged on to this device)




----------------------
no ip domain-lookup      -> disable ip domain lookup  ( if wrong input command cisco will search from dns ).
ip domain-lookup         -> enable ip domain lookup
ip name-server 192.168.10.1    -> setting domain server
ip domain-name toro.com       -> appends domain name to host name  (FQDN)
sh hosts                     -> check domain and check domain cached information from host table


---------------------



debug all -> turn on debug all ( turn debug all on ->> carefull with high traffic router / switch  as it can make the device hang up :) )
no debug all -> turn off all
debug ip rip ->  debug rip




^ proceed with caution!!   check router utilization first!   using command:

show process -> showing process. ( if cpu utilization 50% ++ carefull to turn debug all).

Cisco configuration Register

Im recently graduated from my bachelor degree study. Now im working as Network Engineer at one of biggest cisco gold partner in indonesia. If any of u know Multipolar thats where i make some progress in my career.

Im responsible in managing biggest local bank indonesia network distribution switch, access, wireless, video conference and nexus for SOSA application, and datacenter.  

Below is some note / documentation that maybe useful for u guys.

 

Cisco Configuration Register

All cisco router have  16 bit software register that is written on NVRAM.

By default the configuration register is set to load IOS from flash memory and look for and load startup-config file from NVRAM.

there are many useful of cisco configuration register. One of them is to enter ROM monitor mode to recover cisco password.

first we need to know our cisco configuration register by typing command:

# show version.

Configuration Register is 0x2102     ->  find this line.   ( default setting )

!!to change the configuration register!!

#conf terminal

(config)#config register 0x2142          -> change register 

(config)#end

#wr                                                      -> save config

#reload                                                -> reload router to apply new configuration register.

to recover password on cisco router:

1 boot router

2 while boot perform break to enter router into ROM monitor mode.

3 change register to 0x2142

4 reload router

5 enter privileged mode

6 copy startup-config running-configuration

7 change password

8 reset configuration regiter using default value (0x2102)

9 save and reload

there are other purpose of changing configuration register as:

• select boot source
• control broadcast address
• set terminal baud rate
• enable booting from TFTP server
• disable / enable break button

done.

 

Red Hat Certified System Administrator Documentation part 1

physical / virtual instalation.

install on virtual machine. vmware / virtualbox


min requirement:

-1gb ram.
-optical drive
-20gb disk space
-network connection
-Red Hat 7.x instalation disk
-CentOS 7.x / Scientifi linux 7


============
minimal installation.


-software selection:
> server with GUI.



-hostname: localhost.localdomain > rhelserver.example.com


-setting root password


kdump -> coredump kernel.If server crashed, os creating server memory condition and later can be analyzed using debugger.
> disable kdump  ( klo diaktifin butuh min reserved 161 memory )



- register license?


============

- choose graphical desktop software pattern  (GNOME / KDE )
- CONFIGURE 10GB root partition.
- 1 gb swap partition.
- at least 4gb disk space unused. ( buat logical volume nanti).
- set root password.
- configure DHCP


===========

1.  Understand and use essential tools

# man -k time ( -k = keyword )

# man man-pages

# grep    // filtering utilities.

# date --help  // information option.



=======

start vim -> command mode  -> insert mode (a / i / o / ins ).

esc key -> back to command mode

:wq  // write quit /save file



command mode:
dd -> delete line
u   -> undo
ctrl+r  -> redo
v -> visual mode

gg      -> top of document
$       -> end of line
^ -> beginning of line



:%s/oldtext/newtext/g    -> find all string oldtext and subtitute newtext

//  /g -> apply globally ( more than 1 times, not only 1 times ).


--------------------------------------------------
visual mode

command mode -> v

bisa gerakin cursor sampe ketitik tertentu ( ngeblock text ).
trs delete.





=======
*globbing

using wildcards. used to match filenames


ls host*     // * -> any character.
ls ?host     // ? -> one character.
ls [hm]ost   // [hm] -> host / most.
ls [!hm]ost // any word end with ost.
ls [0-9][0-9]script // start with 2 number then script




ls *host*
ls ??st*
ls [hm]ost        // host / most
ls *[0-9]*        // that have number somewhere in their names.
ls -d [!abcd]*


==========
*piping


stdin //standard input
stdout //standard output
stderr  //standard error


<    //stdin
>    //stdout
>>   //append
2>   //stderr  redirect error to file




mail -s hi root  < .      // command doesnt have to wait for input     anymore

ls > myFile         // writing output to myFile instead of screen.


grep hi * 2> /dev/tty6

==================
*piping

ps aux   ->  too long

ps aux | less // whatever output of command 1 send to cmd 2.

ps aux | awk '{print $2}' | sort -n


ps aux  // print process
awk'{print $2}'  // print 2nd colomn
sort -n   // sort by number


=============

find / -name "*.rpm"  2> /dev/null   // send output error to /dev/null not screen



find / -name "*.rpm"  2> ~/find.error  // send output to home directory and create file find.error


find / -name "*.rpm"  >> rpm-results.txt 2> /dev/null

=============


ls > ~/file_list_list.txt
sort < ~/file_list.txt


sort < file_list.txt > file_list_sorted.txt  // di sort filenya trs masukin ke file_list_sorted.txt