Advance Linux HowTo’s

Cisco OSPF Expect Script

Uncategorized No Responses »

Sep 082009

This Expect script takes as it’s argument, the IP Address of an IOS device that is using AAA Authentication (Username/Password), and returns the OSPF Neighbors of the device.

Usage: ospf_neighbors_script ip address

The script also creates a file with the OSPF Neighbors in the directory it’s run from. The format is “ip address-ospf_neighbors”,

{quickdown:47}

kshort@LinuxStudent:~$ ospf_neighbors_script 10.255.0.26
Username? kshort
Password?

Trying 192.168.0.26…
Connected to 192.168.0.26.
Escape character is ‘^]’.

User Access Verification

Username: kshort
Password:

Test-Router#terminal length 0
Test-Router#sho ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
192.168.1.1       0   FULL/ -        00:00:38    192.168.0.85     Serial1/0.2
192.168.2.1       0   FULL/ -        00:00:38    192.168.0.25     Serial1/0.1
192.168.3.1       1   FULL/BDR        00:00:39    192.168.2.70     GigabitEthernet0/1
192.168.4.1       1   FULL/BDR        00:00:38    192.168.2.66     GigabitEthernet0/0
Test-Router#

HowTo Remaster a LiveCD or LiveDVD using SLAX

Uncategorized No Responses »

Sep 162008

The other day I had to come up with a way to transfer a Solaris Express nv97 DVD 3G image to remote locations while not using the network. The reason for this is, I needed to perform a LiveUpgrade on over 700 boxes and each being at a different locations. So I said to myself I guess I can put this image on a custom LiveDVD… But then I said to myself, which Linux LiveCD/DVD distro will I use???? It has to be small enough so that I can fit the Solaris Express nv97 image as well as the LiveCD Image.

Continue reading “HowTo Remaster a LiveCD or LiveDVD using SLAX” »

Expect Script to find MAC Address on Cisco IOS Devices

Uncategorized No Responses »

Aug 192008

This script will find a MAC address on a Cisco IOS based switch.

Here’s what you’ll see when the switch is successful and unsuccessful finding the MAC address.

Notice it prompts you for your username and password. This script is integrated with the Expect Telnet script on this site.

kshort@LinuxStudent:~$ ./findMACaddress_final 10.10.12.1
Enter the MAC Address? 0013.72fb.3050
Username? kshort
Password?

——————-Here Are the The Results of Your Search——————

vlan mac address type learn age ports
——+—————-+——–+—–+———-+————————–
Supervisor:
* 95 0013.72fb.3050 dynamic Yes 65 Gi1/3

Continue reading “Expect Script to find MAC Address on Cisco IOS Devices” »

Regular Expressions and Commands HowTo

Uncategorized No Responses »

May 182008

There are a bunch of great regular expressions HowTo’s out there….. Now you may be asking why am I creating another??? Well quite simple, I am creating this one because this is not really just a regular expression howto but more a regular expression HowTo with its everyday uses with linux/unix commands. So it will not cover perl/python/ruby/…etc programming languages regular expressions (That will be for another tutorial )

To start this off I will give you a basic introduction to regular expressions using the output
of "ls" and piping it "grep" using the -oE options (The o stands for Exact match and the E stands for Extended Regular Expressions). Using "(BRE and ERE) Basic Regular Expressions and Posix Extended Regular Expressions"…

THIS IS NOT A TUTORIAL BUT A HOWTO!! So this means more examples and less explaining..

Anchors	What it means	Example
^	Start of string	ls \|grep -oE "^Cw+.jpg" Chunka.jpg Chunka1.jpg
$	End of string	ls \|grep -oE "w+(.jpg$)" Chunka.jpg Chunka1.jpg DSCF0732.jpg
b	Word boundary	ls \|grep -oE "bChunkab.jpg" Chunka.jpg
<	Start of word	ls \|grep -oE "<Chw+.jpg" Chunka.jpg Chunka1.jpg
>	End of word	ls Scripts/Python/ \|grep -oE "w+>.py" xen_mac_generate.py

Character Classes	What it means	Example
w	Word	ls \| grep -oE "w" C C
W	Non word	ls \|grep -oE "W" . .

Character Classes

What it means

Example

Word

ls | grep -oE "w"
C
C

Non word

ls |grep -oE "W"
.
.

Quantifiers	what it means	example
*	zero or more times	*ls \| grep -oE "w.jpg"** Chunka.jpg Chunka1.jpg DSCF0732.jpg
+	one or more times	ls \| grep -oE "w+" Chunka Chunka1 DSCF0732
?	matches either once or zero times	ls \| grep -oE "Chunka1?.jpg" Chunka.jpg Chunka1.jpg
{2}	Exactly 2 times	ls \| grep -oE "(^C{2}hw+.jpg)" CChunka.jpg
{1,}	1 or more times	ls \| grep -oE "(^C{1,}hw+.jpg)" CChunka.jpg CCChunka.jpg Chunka.jpg Chunka1.jpg Chunka11.jpg
{1,2}	1 through 2 times	ls \| grep -oE "(^C{1,2}hw+.jpg)" CChunka.jpg Chunka.jpg Chunka1.jpg Chunka11.jpg

Special Characters	What it means	Example
n	New line
r	Carriage return
t	Tab
v	Vertical tab
f	Form feed

Screen HowTo Part 2

Uncategorized No Responses »

May 172008

In the the first part of this HowTo, I gave you the bare minimum to get Screen working
and how to use it on a day to day basis…. This time around I will show you some
of the advanced features of screen that may make your life easier in the terminal..

Before continuing this HowTo please read Part 1 if you do not have previous experience with screen.
So lets start this HowTo with some more Screen Commands…

Continue reading “Screen HowTo Part 2” »

Screen HowTo Part 1

Uncategorized No Responses »

May 112008

I’ve been using screen for the past 3 years and for the first time I’ve decided to seek out more functionality out of it. So last week I spent about 2 hours looking up some of the different functionality that I can use in the day to day. Let me tell you I found a bunch of goodies that I use now religiously (For a week now ).

So for those of you who do not know what a screen session is… (STRAIGHT FROM THE MAN PAGES) Screen is a full-screen window manager that multiplexes a physical terminal between several processes (typically interactive shells). Essentially you can have 30 terminal sessions inside one terminal and much more…..

Continue reading “Screen HowTo Part 1” »

LDAP Client How To

Uncategorized No Responses »

Feb 102008

In this tutorial we will show you how to authenticate to a already configured ldap server

This file "/etc/ldap.conf" is the 1st file that has to be modified as this is the file that tells the system which ldap server to authenticate too.


host yourdomain.com
base dc=yourdomain,dc=com
uri ldap://yourdomain.com/
ldap_version 3
rootbinddn cn=Manager,dc=yourdomain,dc=com
scope sub
timelimit 5
bind_timelimit 5
nss_reconnect_tries 2
pam_login_attribute uid
pam_member_attribute gid
pam_password md5
pam_password exop
nss_base_passwd		ou=People,dc=yourdomain,dc=com
nss_base_shadow		ou=People,dc=yourdomain,dc=com

Now we have to add the passwd in this file "/etc/ldap.secret" so that we can authenticate to the ldap server
```
password
```

Now we have to modify this file "/etc/nsswitch.conf"


passwd:         files ldap
group:          files ldap
hosts:          dns ldap
services:   ldap [NOTFOUND=return] files
networks:   ldap [NOTFOUND=return] files
protocols:  ldap [NOTFOUND=return] files
rpc:        ldap [NOTFOUND=return] files
ethers:     ldap [NOTFOUND=return] files
netmasks:   files
bootparams: files
publickey:  files
automount:  files
sendmailvars:   files
netgroup:   ldap [NOTFOUND=return] files

Now it is time to modify the files in /etc/pam.d/ directory.
First file to be modified is "/etc/pam.d/login"

auth	sufficient	pam_ldap.so
account	sufficient	pam_ldap.so
password	sufficient	pam_ldap.so
session	sufficient	pam_ldap.so


auth            requisite       pam_securetty.so
auth            requisite       pam_nologin.so
auth            sufficient      pam_ldap.so
auth            required        pam_unix.so use_first_pass
auth            required        pam_tally.so onerr=succeed file=/var/log/faillog
account         required        pam_access.so
account         required        pam_time.so
account         required        pam_unix.so
account         sufficient      pam_ldap.so 
password        sufficient      pam_ldap.so
session         required        pam_mkhomedir.so skel=/etc/skel/ umask=0022
session         required        pam_unix.so
session         required        pam_env.so
session         required        pam_motd.so
session         required        pam_limits.so
session         optional        pam_mail.so dir=/var/spool/mail standard
session         sufficient      pam_ldap.so 
session         optional        pam_lastlog.so

Now we modify "/etc/pam.d/shadow"

auth	sufficient	pam_ldap.so
account	sufficient	pam_ldap.so
password	sufficient	pam_ldap.so
session	sufficient	pam_ldap.so


auth            sufficient      pam_rootok.so
auth            required        pam_unix.so
auth            sufficient      pam_ldap.so use_first_pass
account         required        pam_unix.so
account         sufficient      pam_ldap.so
session         required        pam_unix.so
session         sufficient      pam_ldap.so
password        sufficient      pam_ldap.so
password        required        pam_permit.so

Now we modify "/etc/pam.d/passwd"

password

sufficient

pam_ldap.so


password        sufficient      pam_ldap.so 
password        required        pam_unix.so shadow nullok

Now we modify "/etc/pam.d/su"

auth	sufficient	pam_ldap.so
account	sufficient	pam_ldap.so
session	sufficient	pam_ldap.so


auth            sufficient      pam_ldap.so
auth            sufficient      pam_rootok.so
auth            required        pam_unix.so use_first_pass
account         sufficient      pam_ldap.so
account         required        pam_unix.so
session         sufficient      pam_ldap.so
session         required        pam_unix.so

Now we modify "/etc/pam.d/sudo"

auth

sufficient

pam_ldap.so


auth            sufficient      pam_ldap.so
auth            required        pam_unix.so use_first_pass
auth            required        pam_nologin.so

In this file "/etc/pam.d/sshd" you have to add 3 entries, one for auth, one for account, and one for session.

auth	sufficient	pam_ldap.so
account	sufficient	pam_ldap.so
password	required	pam_ldap.so


auth            required        pam_nologin.so
auth            sufficient      pam_ldap.so 
auth            required        pam_env.so
auth            required        pam_unix.so use_first_pass
account         sufficient      pam_ldap.so
account         required        pam_unix.so
account         required        pam_time.so
password        required        pam_ldap.so 
password        required        pam_unix.so
session         required        pam_mkhomedir.so skel=/etc/skel/ umask=0022
session         required        pam_unix_session.so
session         sufficient      pam_ldap.so 
session         required        pam_limits.so

LVM2 How To

Uncategorized No Responses »

Feb 102008

Do you have the need for speed???… OK OK enough with the comments …Before reading this tutorial you should understand a little how LVM works

How to create a physical volume, volume group, and logical volume.

- Figure out which disk and partitions you have that are being used df -h.
- Now we need to run fdisk -l and see all the partitions, including the ones that we have that are not mounted up
- Now that we know which disks and partitions that you can not destroy, we can start our process of creating lvm volumes.
- Lets initialize the first partition..
  pvcreate /dev/sda1.
- Now lets initialize the second partition..
  pvcreate /dev/sdb1.
- To display info on the physical volume, just run this
  pvdisplay.
- vgcreate linuxdynasty /dev/sda1 /dev/sdb1
- vgchange -a y linuxdynasty
- To display info on the volume group, just run this
  vgdisplay.
- Now we create the logical volume.
  lvcreate -L10G -nHomeLV linuxdynasty
- To display info on the logical volume, just run this
  lvdisplay.
- First, we create the file system
  mkfs.ext3 /dev/linuxdynasty/HomeLV
- Second, we mount the file system
  mount -t ext3 /dev/linuxdynasty/HomeLV /home

How to setup a reverse ssh tunnel

Uncategorized No Responses »

Feb 102008

Ever wanted to know how you can ssh into your work desktop/server? Well do not worry any longer…..

- ssh -nNT -R 5000:local_server:22 username@remote_server
- Now from the remote_server run this
  ssh -p5000 localhost…. now we are in our work desktop/server.
- The -n option Redirects stdin from /dev/null. This must be used when ssh is run in the background.
- The -N option does not execute a remote command. This is useful for just forwarding ports.
- The -T option disables pseudo-tty allocation.
- The -R option does tha job of setting up the reverse tunnel.
- Port 5000 is the port that will be listening on the remote_server (this can be any random port over 1024, if you want to run this as a non-root user).
- local_server is the desktop/server that you are creating the connection from.
- Port 22 is the port that you are making the ssh connection to.
- user_name@remote_server is where you are making the ssh connection to for the reverse tunnel.
- In /etc/ssh/sshd_config we need to make sure this is set TCPKeepAlive yes.

How to recover root password

Uncategorized No Responses »

Feb 102008

Have you forgotten the root password on your box and said @#$%%^. Well do not fear, Linux Dynasty is here to save the day.

- First, reboot your system.
- Second, When GRUB comes up type e (got to be quick).
- Third, now select entry that begins with kernel and hit enter.
- Fourth, at the end of the kernel entry type either s or single, now hit enter.
- Fifth, type b, the box will boot up and now you can type in the cmd prompt passwd root. This will reset the password to whatever you like.
- If this does not bring you to a root prompt, then try this.
- Then try appending single init=/bin/bash
Be happy, now you have root access again. or maybe for the first time…
- First, reboot your system.
- Second, When LILO comes up, type in linux s. Hit enter.
- Box will boot into single user mode, which brings you to a root prompt. If this does not happen to you, and ask you for the root password, you will have to do the following.
- Try this linux init=/bin/bash

Older Entries