Linux mint 16 Petra with my laptop HP Pavilion dm4 Notebook PC

hi all,

All this while, I have been struggling with the iwlwifi kernel module working with my Intel wireless card, Centrino Wireless-N 1000 [Condor Peak]. It always having the kernel initialization errors and/or having the wireless connectivity intermittent. There are many posts out in the internet about to remedy this problem. But, none of them are working for me, until I upgraded my OS to Linux Mint 16, Petra with a little bit of tweaks. So, I would like to take this opportunity to list down all the changes in order to make it works.

1.   I have blacklisted my bluetooth driver. It is always rare to use and this bluetooth kernel is always fighting with the iwldvm module to initialize the hardware. So, I decided to blacklist it.

tehtarik ~ # tail -n2  /etc/modprobe.d/blacklist.conf
# Hiu added this
blacklist bluetooth

2. I have taken out all of the unrelated intel wireless firmware. For more details you can refer it to http://wireless.kernel.org/en/users/Drivers/iwlwifi. I know my firmware is /lib/firmware/iwlwifi-1000-5.ucode. So, I purposely taken out the rest of the intel firmware and move them under my /root directory like this.

tehtarik ~ # ls -al /root/iwlwifi/
total 8068
drwxr-xr-x  2 root root   4096 Dec  1 22:23 .
drwx------ 12 root root   4096 Dec 13 00:53 ..
-rw-r--r--  1 root root 337572 Apr 25  2013 iwlwifi-100-5.ucode
-rw-r--r--  1 root root 689680 Apr 25  2013 iwlwifi-105-6.ucode
-rw-r--r--  1 root root 701228 Apr 25  2013 iwlwifi-135-6.ucode
-rw-r--r--  1 root root 695876 Apr 25  2013 iwlwifi-2000-6.ucode
-rw-r--r--  1 root root 707392 Apr 25  2013 iwlwifi-2030-6.ucode
-rw-r--r--  1 root root 670172 Jul 10 22:59 iwlwifi-3160-7.ucode
-rw-r--r--  1 root root 150100 Apr 25  2013 iwlwifi-3945-2.ucode
-rw-r--r--  1 root root 187972 Apr 25  2013 iwlwifi-4965-2.ucode
-rw-r--r--  1 root root 340696 Sep 30 22:33 iwlwifi-5000-5.ucode
-rw-r--r--  1 root root 337400 Apr 25  2013 iwlwifi-5150-2.ucode
-rw-r--r--  1 root root 454608 Apr 25  2013 iwlwifi-6000-4.ucode
-rw-r--r--  1 root root 444128 Apr 25  2013 iwlwifi-6000g2a-5.ucode
-rw-r--r--  1 root root 677296 Apr 25  2013 iwlwifi-6000g2a-6.ucode
-rw-r--r--  1 root root 679436 Apr 25  2013 iwlwifi-6000g2b-6.ucode
-rw-r--r--  1 root root 469780 Apr 25  2013 iwlwifi-6050-5.ucode
-rw-r--r--  1 root root 682892 Jul 10 22:59 iwlwifi-7260-7.ucode

3. I have put some of the important kernel parameter tweaks of iwlwifi. Here is how it is look like. This line is really important: options iwlwifi 11n_disable=1 bt_coex_active=0. Actually, there are many people are documenting the same tweaks on this kernel module. But, for me these are the mostly important tweaks and you must have it.


tehtarik ~ # cat /etc/modprobe.d/iwlwifi.conf
# /etc/modprobe.d/iwlwifi.conf
# iwlwifi will dyamically load either iwldvm or iwlmvm depending on the
# microcode file installed on the system.  When removing iwlwifi, first
# remove the iwl?vm module and then iwlwifi.
remove iwlwifi \
(/sbin/lsmod | grep -o -e ^iwlmvm -e ^iwldvm -e ^iwlwifi | xargs /sbin/rmmod) \
&& /sbin/modprobe -r mac80211
options iwlwifi 11n_disable=1 bt_coex_active=0


With all the steps applied onto my laptop, I don't have any more wireless connectivity hiccup and happily ever after. I don't need to figure out the alternative way of configuring the ndiswrapper or buying another external usb wireless adapter.  Hope it helps you all.

Thanks.

Python in Action: ssh paramiko client - first release to github

I have been working on the same codes for almost a week from now. I feel that I am more comfortable with the output and I decided to push it over to github and hope that it could help others system engineer who needed to do the automation with a large group of servers/VMs. You can clone the codes from here.


Here is the output that you will be getting.


hiuy@nasilemak ~/ssh-paramiko-client $ ./pyssh.py
Password:
-- Welcome to ssh paramiko --
ssh > help
Usage - pyssh.py
 addhost      - add host with the comma delimitter
 addhostfile  - add host with a absolute path of a file
 rmhost       - remove host with the comma delimitter
 lshost       - list hosts
 ping         - do a ping test to the added host list
 connect      - establish ssh connection to the added host list
 run          - run a specific command on the connected host
 close        - close the ssh connect to the added host list
 quit         - quit the session
ssh > addhost centos64-1, centos64-2
host added: ['centos64-1', 'centos64-2']
ssh > ping
host centos64-1 PING OK
host centos64-2 PING OK
ssh > connect
Connected host: centos64-1
Connected host: centos64-2
Total connected hosts: 2 out of 2
ssh > run uptime
host: centos64-1
     05:49:07 up  4:24,  1 user,  load average: 0.00, 0.10, 0.10
host: centos64-2
     05:49:07 up  4:25,  1 user,  load average: 0.00, 0.00, 0.00
ssh > run uname -a
host: centos64-1
    Linux localhost.localdomain 2.6.32-358.23.2.el6.x86_64 #1 SMP Wed Oct 16 18:37:12 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
host: centos64-2
    Linux localhost.localdomain 2.6.32-358.23.2.el6.x86_64 #1 SMP Wed Oct 16 18:37:12 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
ssh > run rpm -qa | grep kernel
host: centos64-1
    kernel-devel-2.6.32-358.el6.x86_64
    kernel-headers-2.6.32-358.23.2.el6.x86_64
    abrt-addon-kerneloops-2.0.8-16.el6.centos.1.x86_64
    dracut-kernel-004-303.el6.noarch
    libreport-plugin-kerneloops-2.0.9-15.el6.centos.1.x86_64
    kernel-firmware-2.6.32-358.23.2.el6.noarch
    kernel-devel-2.6.32-358.23.2.el6.x86_64
    kernel-2.6.32-358.el6.x86_64
    kernel-2.6.32-358.23.2.el6.x86_64
host: centos64-2
    kernel-devel-2.6.32-358.el6.x86_64
    kernel-headers-2.6.32-358.23.2.el6.x86_64
    abrt-addon-kerneloops-2.0.8-16.el6.centos.1.x86_64
    dracut-kernel-004-303.el6.noarch
    libreport-plugin-kerneloops-2.0.9-15.el6.centos.1.x86_64
    kernel-firmware-2.6.32-358.23.2.el6.noarch
    kernel-devel-2.6.32-358.23.2.el6.x86_64
    kernel-2.6.32-358.el6.x86_64
    kernel-2.6.32-358.23.2.el6.x86_64
ssh > close
ssh > quit
hiuy@nasilemak ~/ssh-paramiko-client $

If you are keen to develop and contribute to this codes, please drop me an email, and we can work it out together. All of the new ideas are mostly welcome. Thanks.

visudo: Are you really a joker?

What you see sometimes doesn't mean what you think!

I just came across a funny configuration bits on the /etc/sudoers file lately on centos64. The default configuration for /etc/sudoers comes with this (the last 2 lines at the config). Okay, gentlemen. Please pay attention with this. If you would be creating a directory like /etc/sudoers.d/, then basically you are asking sudoer to look at any of the small snippets with in it, or what they called it as drop-in files. Make sure you do have the snippet and stay within this directory. Otherwise, your visudo -c -f /etc/sudoers will complain and shout at you when you save it.

What is make me laugh at it was the syntax of the configuration #includedir. It is telling you that it has been turned on. Don't be fooled because it was commented out (as usual, a sys admin will think the same across, further more most of the tags was commented out). It *doesnt* mean what you think. So, watch out! It bites you!

## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment)
#includedir /etc/sudoers.d

Python in Action: Paramiko handling ssh connection

I came across the ssh interactive session from bash long time ago using the expect. But, this morning I am exploring paramiko, and start to draft a stupid easy codes to test out the library. It is clean and blazing fast. Hope this small chunks of codes can get you started with all the complicated paramiko codes.

#!/usr/bin/python                                                          
import os                                                                  
import paramiko                                                            
import getpass                                                             
                                                                            
user=os.getlogin()                                                         
print "Connecting via %s: what is your password?" % user                   
pw = getpass.getpass()                                                     
ssh = paramiko.SSHClient()                                                 
#ssh.load_host_keys()                                                      
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())                  
ssh.connect('centos64-1', username=user, password=pw)                      
stdin, stdout, stderr = ssh.exec_command('uname -a')                       
print "output", stdout.read()                                              
ssh.close() 

 
After a day so, I feel like I want to do a little of enhancement out of it. So, I recode it something like below. Still feeling it is not as neath as I love to. But, overall it can carry out the work.

#!/usr/bin/python
import os
import paramiko
import getpass
import socket

def get_credential():
    user=os.getlogin()
    print "Connecting via [%s]: what is your password?" % user
    pw = getpass.getpass()
    return (user, pw)

def ssh_connect():
    (user, pw) = get_credential()
    try:
        ssh = paramiko.SSHClient()
        #ssh.load_host_keys()
        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        ssh.connect('centos64-1', username=user, password=pw)
        stdin, stdout, stderr = ssh.exec_command('uname -a')
        print "output: ", stdout.read()
        ssh.close()
    except paramiko.SSHException, e:
        print "Password is invalid:" , e
    except paramiko.AuthenticationException:
        print "Authentication failed for some reason"
    except socket.error, e:
        print "Socket connection failed:", e

def main():
    ssh_connect() 

if __name__ == '__main__':                                                    
    main()                 


After a day so, I have done some polishing on the same codes. Now, it can accept a list of target hosts with a comma delimiter. Then, the script will be connecting to target hosts one by one. Feel free to copy/use it. Thanks!

#!/usr/bin/python
import os
import paramiko
import getpass
import socket

def get_host():
    target_host = []
    input = raw_input("What is your target host? ")
    for item in input.split(","):
        target_host.append(item.strip())
    return target_host

def get_credential():
    pw = ""
    user=os.getlogin()
    print "Connecting via [%s]: what is your password?" % user
    while not pw:
        pw = getpass.getpass()
    return (user, pw)


def ssh_connect():
    target_host = get_host()
    (user, pw) = get_credential()

    ssh = paramiko.SSHClient()
    #ssh.load_host_keys()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    for h in target_host:
        try:
            print "Connecting to %s ..." % h
            ssh.connect(h, username=user, password=pw)
            stdin, stdout, stderr = ssh.exec_command('uname -a')
            print "%s>" % h,stdout.read()
        except paramiko.SSHException, e:
            print "Password is invalid:" , e
        except paramiko.AuthenticationException:
            print "Authentication failed for some reason"
        except socket.error, e:
            print "Socket connection failed on %s:" % h, e
    ssh.close()
def main():
    ssh_connect()

if __name__ == '__main__':                                                    
    main()


Here is the output that I got.

hiuy@nasilemak ~ $ ./pyssh.py
What is your target host? centos64-1, centos64-2
Connecting via [hiuy]: what is your password?
Password:
Connecting to centos64-1 ...
centos64-1> Linux centos64-1.hiu.com 2.6.32-358.18.1.el6.x86_64 #1 SMP Wed Aug 28 17:19:38 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

Connecting to centos64-2 ...
centos64-2> Linux localhost.localdomain 2.6.32-358.el6.x86_64 #1 SMP Fri Feb 22 00:31:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

Script to report the HBA cards status

I have a small function to detect the emulex, and qlogic HBA cards for a quick one. If you find it useful in your automation you can embed this function to your script and start calling it. Hope that it helps you in your works. Thanks!

function check_hba ()
{

        # Checking Emulex HBA cards status

        if grep -q -i "online" /sys/class/fc_host/host*/port_state 2>/dev/null
        then
                num_online_hba=`grep -i "online" /sys/class/fc_host/host*/port_state | wc -l`
                total_hbas=`ls -1 /sys/class/fc_host/host*/node_name | wc -l`

                echo "Linux discovered $num_online_hba HBAs is online out of $total_hbas cards."

                for h in `ls -1 /sys/class/fc_host/host*/node_name | awk -F/ '{print $5}'`
                do
                        wwn=`cat /sys/class/fc_host/$h/port_name`
                        state=`cat /sys/class/fc_host/$h/port_state`
                        #modelname=`cat /sys/class/scsi_host/$h/modelname`
                        #echo "HBA $modelname : $wwn is $state"
                        echo "HBA : $wwn is $state"
                done
        fi

        # Checking Qlogic HBA cards status
        if grep -q -i "ready" /proc/scsi/qla2xxx/* 2>/dev/null
        then
                total_hbas=`ls -1 /proc/scsi/qla2xxx/* | wc -l`
                num_online_hba=`grep -i "ready" /proc/scsi/qla2xxx/*| wc -l`

                echo "Linux discovered $num_online_hba is online out of $total_hbas cards."

                for h in `ls -1 /proc/scsi/qla2xxx/*`
                do
                        wwn=`cat $h|grep "scsi-qla.-adapter-port*" | awk -F= '{print $2}' | sed -e 's|;||g'`
                        grep -i -q "Host adapter.*ready" $h && echo "HBA : $wwn is Online" || echo "HBA : $wwn is Offline"
                done
        fi

}

LVM and hosttag

hi all,

LVM is working well with host tag especially when working for a active/passive cluster nodes. There are just some simple lines needed at /etc/lvm/lvm.conf

1. volume_list = [ "vg00", "vg01", "vg02", "vg03", "vg04", "vg05" ]
2. tags  { hosttags = 1 }


At the same time, you have to create another conf file with this command

echo "activation { volume_list=["@`hostname -f`"] }" >  /etc/lvm/lvm_`hostname -f`.conf

So, the result with the something like this.

[root@node01c lvm]# cat /etc/lvm/lvm_node01c.hiu.com.conf
activation { volume_list=["@node01c.hiu.com"] }

Once you are done, pretty much you are done.

When you are importing the vg01, you will need to add a tag onto it: vgchange --addtag vg01 upon the activation. Otherwise, you have to deport it so another node within the cluster can import it. To deport it, you have to do vgchange --deltag vg01. 

if you are working well, you will notice that the tagging is working against the lvdisplay too. For example:

[root@node01c lvm]# lvdisplay @node01c.hiu.com

  --- Logical volume ---

  LV Path                /dev/vg02/lvol01

  LV Name                lvol01

  VG Name                vg02

  LV UUID                CXLHnj-FWUY-Puej-r2SN-S7d5-Bkse-Ufx9yH

  LV Write Access        read/write

  LV Creation host, time node01c.hiu.com, 2013-10-03 15:34:30 +0800

  LV Status              available

  # open                 1

  LV Size                71.98 GiB

  Current LE             18428

  Segments               1

  Allocation             inherit

  Read ahead sectors     auto

  - currently set to     256

  Block device           253:19

Whereas, in the passive node, you wont find any output is printed.

[root@node02c lvm]# lvdisplay @node02c.hiu.com

[root@node02c lvm]#

Another method to determine your tagging is working fine by using the command lvs.


[root@node01c lvm]# lvs
  LV     VG   Attr     LSize  Pool Origin Data%  Move Log Copy%  Convert
  crash  vg00 -wi-ao--  7.81g
  home   vg00 -wi-ao--  4.00g
  opt    vg00 -wi-ao--  4.00g
  tmp    vg00 -wi-ao--  4.00g
  usr    vg00 -wi-ao--  4.00g
  var    vg00 -wi-ao--  4.00g
  lvol01 vg01 -wi-ao--  3.98g
  lvol01 vg02 -wi-ao-- 71.98g
  lvol01 vg03 -wi-ao--  1.98g
  lvol01 vg04 -wi-ao-- 61.98g
  lvol01 vg05 -wi-ao--  4.98g

[root@node02c lvm]# lvs
  LV     VG   Attr     LSize  Pool Origin Data%  Move Log Copy%  Convert
  crash  vg00 -wi-ao--  7.81g
  home   vg00 -wi-ao--  4.00g
  opt    vg00 -wi-ao--  4.00g
  tmp    vg00 -wi-ao--  4.00g
  usr    vg00 -wi-ao--  4.00g
  var    vg00 -wi-ao--  4.00g
  lvol01 vg01 -wi-----  3.98g
  lvol01 vg02 -wi----- 71.98g
  lvol01 vg03 -wi-----  1.98g
  lvol01 vg04 -wi----- 61.98g
  lvol01 vg05 -wi-----  4.98g

with this output, you can clearly see that there is a string like "wi-ao" appended onto the activated volume at the active node. 

Configuring bonding: RTNETLINK answers: File exists

hi all,

Today, I am trying to configure a active/passive bonding for linux, but keep hitting the same error when I restarted the network services.

[root@node01 network-scripts]# /etc/init.d/network restart
Shutting down interface bond0:                             [  OK  ]
Shutting down interface bond1:                             [  OK  ]
Shutting down interface eth12:                             [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface bond0:                               [  OK  ]
Bringing up interface bond1:                               [  OK  ]
Bringing up interface eth2:  RTNETLINK answers: File exists
                                                           [  OK  ]
Bringing up interface eth12:                               [  OK  ]

I have spent a couples of minutes to trouble but no luck. I took a rest then when back and look closely at my ifcfg-eth* configuration files and I discovered a silly mistake like this. I have stated SLAVE=no at ifcfg-eth2. that's why it keeps on complaining the problem.

[root@node01 network-scripts]# grep bond1 ifcfg-*

ifcfg-bond1:DEVICE=bond1

ifcfg-eth2:MASTER=bond1

ifcfg-eth9:MASTER=bond1

[root@node01 network-scripts]# cat ifcfg-eth2

DEVICE=eth2

BOOTPROTO=none

ONBOOT=yes

MASTER=bond1

SLAVE=no

USERCTL=no

HWADDR=3C:D9:2B:F4:A1:9A

[root@node01 network-scripts]# cat ifcfg-eth9

DEVICE=eth9

BOOTPROTO=none

ONBOOT=yes

MASTER=bond1

SLAVE=yes

USERCTL=no

HWADDR=44:1E:A1:17:F8:76

Hope that you wont be as silly as I am.

After all, you can verify your configuration at

[root@node01 network-scripts]# cat /proc/net/bonding/bond1
Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009)

Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: eth2
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 1000
Down Delay (ms): 0

Slave Interface: eth2
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 3c:d9:2b:f4:a1:9a
Slave queue ID: 0

Slave Interface: eth9
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 44:1e:a1:17:f8:76
Slave queue ID: 0

Script to kill the command with timeout.

If you don't bother to wait the command to timeout. You can have a bash script as a wrapper to clean the PID within your defined timeout values. I came across the same function like this before in my senior codes, just can't recall how is the codes goes. Now, I am totally rewrite it based on my memory. Hope that it can help you when doing bash coding.

function run_with_command () {

CMD=$1

TIMEOUT=$2

COUNTER=0

${CMD} &

CMD_PID=$!

while ps $CMD_PID > /dev/null && [ $COUNTER -lt $TIMEOUT ]; do

sleep 1

COUNTER=$((COUNTER+1))

done

if [ $COUNTER -eq $TIMEOUT ]

then

kill $CMD_PID 2>/dev/null

fi

wait $CMD_PID 2>/dev/null

}

Script to rescan the offline disk

I have a function to detect the offline disks, delete them then, re-scan it. Hope that it can help you from your daily Linux operation.



function fix_stale_disk ()
{
        echo_header
        if grep -q -i offline /sys/block/*/device/state
        then

                #Checking for offline disks
                echo "Linux discovered offline disks."
                grep -l -i offline /sys/block/*/device/state

                echo "Do you want to fix the offline disks? (y/n)"
                read ans
                if [[ "$ans" == "y" || "$ans" == 'Y' ]]
                then

                        for block in `grep -l -i offline /sys/block/*/device/state | awk -F/ '{print $4}'`
                        do
                                status=""
                                echo -n "Deleting /dev/$block ..."
                                echo 1 > /sys/block/$block/device/delete
                                if [[ "$?" -eq "0" ]]
                                then
                                        status="Done"
                                else
                                        status="Failed"
                                fi
                                sleep 5
                                echo " $status"
                        done

                        echo ""
                        #Rescanning the disks.
                        for f in `ls -1 /sys/class/fc_host/*/issue_lip 2>/dev/null`
                        do
                                echo "Rescanning $f ..."
                                echo 1 > $f
                                sleep 5
                        done
                else
                        echo "You have halted the operation."
                        exit 1
                fi
        else
                echo "All disks are good."

        fi
}

Linux, Who eaten up my memory?

Linux, Who eaten up my memory?

if you want to know which PID that chewing up your memory and not letting go? Here is the small bash script.

#!/bin/bash
echo
for pid in `grep -i VmSize /proc/*/status | sort -k +2n | tail -n10 | awk -F"/" '{print $3}'`
do
        echo "************************"
        echo "PID: $pid"
        echo "Allocated memory: `grep VmSize /proc/$pid/status | awk -F":" '{print $2" "$3}'`"
        echo `ps -aef | grep $pid | grep -v grep`

done
echo

Python in Action: Search for big file in Linux

 Python in Action: Search for big file in Linux

Here is the codes. Hope that you will love it.

import os

def search():
    filesize = 0
    filename = ''
    for root, dirs, files in os.walk('/'):
        for f in files:
            f = os.path.join(root, f)
            if os.path.isfile(f):
                if os.path.getsize(f) > filesize:
                    filesize = os.path.getsize(f)
                    filename = os.path.getrealpath(f)
                    print "file: %s ==> size: %s" % (filename, filesize)
                else:
                    break
 
if __name__ == '__main__':
    search()

whoami?? whoami??

hi all,

I came across a weird case when I am working today. But, I am able to solve the problem in a minute. Just hope that I can share it out. The problem sounds as like below.

login as: hiuy
Last login: Fri Jun  7 09:01:01 2013 from 16.189.90.136
-bash: /etc/profile: Permission denied
-bash-3.2$

-bash-3.2$ id

uid=121738973 gid=6347 groups=10,6347,12132,12178

-bash-3.2$ whoami

whoami: cannot find name for user ID 121738973

[root@test ~]# ls -al /etc/passwd /etc/shadow /etc/group

-rw-r--r-- 1 root root 29575 Jun  7 08:02 /etc/passwd

-rw-r--r-- 1 root root 4368 Jun  7 08:55 /etc/group

-r-------- 1 root root 9012 Jun  7 08:02 /etc/shadow

The permission for the three important files are perfectly looks okay. So, What is the fault??

This is the hint....

-bash-3.2$ ls -al /etc/passwd

ls: /etc/passwd: Permission denied

The Answer is here...

[root@test /]# ls -al | grep etc

drwx------  89 root root 12288 Jun  7 08:55 etc

etc is having 700 only. No permission for mortal user to read and accessing /etc/passwd! So, chmod it to 755 /etc, and that's the end of the story!

This is cunning, but I like it....

Openldap bug on centos6,4

Openldap bug on centos6,4

When you are setting up the new openldap server, specifically with the following combination.

[root@centos6-01 openldap]# cat /etc/centos-release
CentOS release 6.4 (Final)

[root@centos6-01 openldap]# uname -r
2.6.32-358.6.1.el6.x86_64

[root@centos6-01 openldap]# rpm -qa | grep openldap-servers
openldap-servers-2.4.23-32.el6_4.1.x86_64

Most of the problem that you will hit when you are trying to add a first ldap entry from a ldif file was "ldap_bind invalid credentials (49)". Luckily, when you are doing a search from google, you should be able to find this link to help you to solve the problem.  http://www.ezylinux.com/en/red-hat-6-how-to-fixes-ldapadd-ldap_bind-invalid-credentials-49/. However, right after you have applied the commands, I just found "ANOTHER" bug on the daemon script as depicted as below. Even though the daemon script yielded an error message, but the slapd process will still spawned out, which I think it is a bit ugly.

[root@centos6-01 openldap]# /etc/init.d/slapd start

ln: accessing `/var/run/openldap/slapd.pid': No such file or directory

[root@centos6-01 openldap]# pidof slapd

1857

[root@centos6-01 openldap]# ps -eaf | grep slapd

ldap      1857     1  0 15:07 ?        00:00:00 /usr/sbin/slapd -h  ldap:/// ldapi:/// -u ldap

I keep on finding for bug list reported from the redhat bugzilla, but I have no luck. So, I decided to hack the daemon script, /etc/init.d/slapd. In this script, you will find some lines sound as below.

 # Start daemons.

        echo -n $"Starting $prog: "

        daemon --pidfile=$pidfile --check=$prog $ulimit ${slapd} -h "\"$harg\"" -u ${user} $OPTIONS $SLAPD_OPTIONS

        RETVAL=$?

        if [ $RETVAL -eq 0 ]; then

                touch $lockfile

                ln $slapd_pidfile $pidfile

        fi

So, this is my hacked version. Please pay more attention on the highlighted lines.

 # Start daemons.

        echo -n $"Starting $prog: "

        daemon --pidfile=$pidfile --check=$prog $ulimit ${slapd} -h "\"$harg\"" -u ${user} $OPTIONS $SLAPD_OPTIONS

        pidof ${slapd} > $pidfile

        RETVAL=$?

        if [ $RETVAL -eq 0 ]; then

                touch $lockfile

                #ln $slapd_pidfile $pidfile

                ln $pidfile $slapd_pidfile

        fi

With this, I can start/stop my daemon with no problem.

[root@centos6-01 cn=config]# /etc/init.d/slapd start

Starting slapd:                                            [  OK  ]

[root@centos6-01 cn=config]# /etc/init.d/slapd stop

Stopping slapd:                                            [  OK  ]

I am not sure if Centos community aware of this bug. But, I am just sharing it out, in hoping that the bug will be fixed in future. 

Network devices comes with UUID? What is nmcli? PART 1

Network devices comes with UUID? What is nmcli? PART 1

The whole notion to explore on the network configuration was because of the curiosity when I bounced the network services and found out "something" new.

 [root@localhost network-scripts]# /etc/init.d/network restart
Shutting down interface eth0:  Device state: 3 (disconnected)
                                                           [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:  Active connection state: activating
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/10
state: activated
Connection activated
                                                           [  OK  ]

So, what is the highlighted lines telling me? I have never seen this before in my past 10 years using Linux. So, when I dig more on it, I found out it was actually invoked by the /sbin/ifup command at the /etc/init.d/network script, something like ifup eth0 boot. If you drill down the script in the debug mode, then you will realize ifup is another wrapper script on top of nmcli command, where it called out something like this

nmcli con up UUID 2b58ae6b-8ad0-4fcc-ad99-582fa16d2fd9

Well, this is pretty new to me. Network configuration that ties to a UUID? That's awesome. Is nmcli (network manager cli) going to replace ifconfig command? Personally, I have a lot of doubts. Let's find out more..

This is how a ifcfg-eth0 looks like in Centos6.4

[root@localhost network-scripts]# cat ifcfg-eth0
DEVICE="eth0"
BOOTPROTO="dhcp"
HWADDR="00:0C:29:10:6A:D3"
IPV6INIT="yes"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="2b58ae6b-8ad0-4fcc-ad99-582fa16d2fd9"


Now, nmcli tagging each of the NIC with a UUID. With that in place, nmcli make use of this and prints out something like this for you as a more user-friendly format. From the man file, it tells us that there are three main objects that governed by nmcli which is nm, con, dev.

nm: Network Manager. Use this object to inquire and change state of NetworkManager.

con: Connection. Get information about NetworkManager's connections.

dev: Device. Get information about devices.

[root@localhost network-scripts]# nmcli nm status
RUNNING         STATE           WIFI-HARDWARE   WIFI       WWAN-HARDWARE   WWAN
running         connected       enabled         enabled    enabled         enabled

[root@localhost network-scripts]# nmcli con status
NAME                      UUID                                   DEVICES    SCOPE    DEFAULT  VPN
System eth0               2b58ae6b-8ad0-4fcc-ad99-582fa16d2fd9   eth0       system   yes      no

[root@localhost network-scripts]# nmcli dev
DEVICE     TYPE              STATE
eth0       802-3-ethernet    connected

[root@localhost network-scripts]# nmcli dev list
GENERAL.DEVICE:                 eth0
GENERAL.TYPE:                   802-3-ethernet
GENERAL.DRIVER:                 e1000
GENERAL.HWADDR:                 00:0C:29:10:6A:D3
GENERAL.STATE:                  connected
CAPABILITIES.CARRIER-DETECT:    yes
CAPABILITIES.SPEED:             1000 Mb/s
WIRED-PROPERTIES.CARRIER:       on
IP4-SETTINGS.ADDRESS:           192.168.195.133
IP4-SETTINGS.PREFIX:            24 (255.255.255.0)
IP4-SETTINGS.GATEWAY:           192.168.195.2
IP4-DNS1.DNS:                   192.168.195.2

In sync with this command, there is another cool command, called, nm-tool.

[root@localhost network-scripts]# nm-tool

NetworkManager Tool

State: connected

- Device: eth0  [System eth0] --------------------------------------------------
  Type:              Wired
  Driver:            e1000
  State:             connected
  Default:           yes
  HW Address:        00:0C:29:10:6A:D3

  Capabilities:
    Carrier Detect:  yes
    Speed:           1000 Mb/s

  Wired Properties
    Carrier:         on

  IPv4 Settings:
    Address:         192.168.195.133
    Prefix:          24 (255.255.255.0)
    Gateway:         192.168.195.2

    DNS:             192.168.195.2


From here, we can see there are a lot of useful information, e.g  kernel module, e1000 is used, speed, carrier state,  HW address.

Conclusion: I don't really see the need of nmcli, why it is being used? Isn't that another command to the native the command like ip? But, it is worth to reread the ifup script, and do a comparison between the old ifup and the new ifup script.

Mount CDROM in CENTOS? Hassle?

Mount CDROM in CENTOS? Hassle?

What a hassle finding the CD ROM device in Centos. The new release of Centos putting CD ROM device at /dev/sr0. Let look at the below, then you will know what is going on.

[root@localhost proc]# find /dev -name cdrom
/dev/cdrom
/dev/.udev/links/cdrom

[root@localhost proc]# ls -al /dev/cdrom
lrwxrwxrwx. 1 root root 3 May  9 13:46 /dev/cdrom -> sr0

[root@localhost proc]# ls -al /dev/| grep sr0
lrwxrwxrwx.  1 root root           3 May  9 13:46 cdrom -> sr0
lrwxrwxrwx.  1 root root           3 May  9 13:46 dvd -> sr0
lrwxrwxrwx.  1 root root           3 May  9 13:46 scd0 -> sr0
brw-rw----.  1 root cdrom    11,   0 May  9 13:46 sr0

[root@localhost proc]# mount -r -t iso9660 /dev/sr0 /mnt

[root@localhost proc]# cd /mnt/

[root@localhost mnt]# ls -al
total 685
dr-xr-xr-x.  7 root root   4096 Mar  5 10:33 .
dr-xr-xr-x. 22 root root   4096 May  9 13:44 ..
-r--r--r--.  2 root root     14 Mar  5 10:28 CentOS_BuildTag
-r--r--r--.  1 root root     31 Mar  5 10:31 .discinfo
dr-xr-xr-x.  3 root root   2048 Mar  4 17:05 EFI
-r--r--r--.  2 root root    212 Mar  2 09:46 EULA
-r--r--r--.  2 root root  18009 Mar  2 09:46 GPL
dr-xr-xr-x.  3 root root   2048 Mar  4 17:05 images
dr-xr-xr-x.  2 root root   2048 Mar  4 17:05 isolinux
dr-xr-xr-x.  2 root root 649216 Mar  5 10:31 Packages
-r--r--r--.  2 root root   1354 Mar  2 09:45 RELEASE-NOTES-en-US.html
dr-xr-xr-x.  2 root root   4096 Mar  5 10:33 repodata
-r--r--r--.  2 root root   1706 Mar  2 09:46 RPM-GPG-KEY-CentOS-6
-r--r--r--.  2 root root   1730 Mar  2 09:46 RPM-GPG-KEY-CentOS-Debug-6
-r--r--r--.  2 root root   1730 Mar  2 09:46 RPM-GPG-KEY-CentOS-Security-6
-r--r--r--.  2 root root   1734 Mar  2 09:46 RPM-GPG-KEY-CentOS-Testing-6
-r--r--r--.  1 root root   3380 Mar  5 10:33 TRANS.TBL
-r--r--r--.  1 root root    338 Mar  5 10:33 .treeinfo

Voila, I am done. Next remember, you can source for /dev/sr0. For me, this is something new.

Linux dm-multipath on local disk?

Compiled by : Hiu, Yen-Onn (yenonn@gmail.com), 7^th May 2013

Problem: If you are running a Linux, RHEL5 or RHEL6, some machines have local scsi disks that been detected by dm-multipath. It is a known fault on the configuration and strongly not recommended for local disks. Please read this link from Redhat for future clarification. (https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/DM_Multipath/#ignore_localdisk_procedure)

This is the scenario when you first login to a login problematic Linux/dm-multipath server.  You should see the multipathing is acquiring the / and /boot mount points. As the result, we can’t stop the multipathd because some of the disks are being used by the system.

Even with some of the /etc/multipath.conf blacklisted local scsi disk, we still can see the local disks are not been ignored by the dm-multipath.

[root@s11t0008c ~]# uname -r

2.6.32-220.4.2.el6.x86_64

[hiuy@s11t0008c ~]$ df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/mapper/mpathap3 1008M  459M  498M  48% /

tmpfs                  32G     0   32G   0% /dev/shm

/dev/mapper/mpathap1  186M   59M  118M  34% /boot

/dev/mapper/vg00-home

                      4.0G  158M  3.6G   5% /home

/dev/mapper/vg00-opt  4.0G  1.7G  2.1G  45% /opt

/dev/mapper/vg00-tmp  4.0G  138M  3.7G   4% /tmp

/dev/mapper/vg00-usr  4.0G  1.3G  2.6G  33% /usr

/dev/mapper/vg00-var  4.0G  634M  3.2G  17% /var

/dev/mapper/vg00-crash

                      7.7G  923M  6.4G  13% /var/crash

tmpfs                 4.0K     0  4.0K   0% /dev/vx

This is the snippet of the /etc/multipath.conf

blacklist {

#       devnode ".*"

        devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"

        devnode "^hd[a-z]"

        devnode "^dcssblk[0-9]*"

        device {

                vendor "DGC"

                product "LUNZ"

        }

        device {

                vendor "IBM"

                product "S/390.*"

        }

        # don't count normal SATA devices as multipaths

        device {

                vendor  "ATA"

        }

        # don't count 3ware devices as multipaths

        device {

                vendor  "3ware"

        }

        device {

                vendor  "AMCC"

        }

        # nor highpoint devices

        device {

                vendor  "HP.*"

        }

        wwid 3600508b1001030363945374330300f00

}

[root@s11t0008c ~]# multipath -ll

mpatha (3600508b1001030363945374330300f00) dm-0 HP,LOGICAL VOLUME

size=279G features='1 queue_if_no_path' hwhandler='0' wp=rw

`-+- policy='round-robin 0' prio=1 status=active

  `- 0:0:0:1 sda 8:0 active ready running

[root@s11t0008c sysconfig]# cat /etc/fstab

#

# /etc/fstab

# Created by anaconda on Fri Sep 28 08:12:03 2012

#

# Accessible filesystems, by reference, are maintained under '/dev/disk'

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

#

UUID=e65ac106-53a5-4f0d-bd5e-ad563883c7d8 /                       ext4    defaults        1 1

UUID=4d5a5077-8582-4f3d-8708-2588644686d1 /boot                   ext3    defaults        1 2

/dev/mapper/vg00-home   /home                   ext4    defaults        1 2

/dev/mapper/vg00-opt    /opt                    ext4    defaults        1 2

/dev/mapper/vg00-tmp    /tmp                    ext4    defaults        1 2

/dev/mapper/vg00-usr    /usr                    ext4    defaults        1 2

/dev/mapper/vg00-var    /var                    ext4    defaults        1 2

UUID=5caa587b-f2d4-4063-9db3-f9b2901e816d swap                    swap    defaults        0 0

tmpfs                   /dev/shm                tmpfs   defaults        0 0

devpts                  /dev/pts                devpts  gid=5,mode=620  0 0

sysfs                   /sys                    sysfs   defaults        0 0

proc                    /proc                   proc    defaults        0 0

/dev/vg00/crash /var/crash      ext3    defaults        2       2

In order to trace the UUID on the / mount point, we can query the blkid table on the devices that had been registered. The

[root@s11t0008c ~]# blkid -U e65ac106-53a5-4f0d-bd5e-ad563883c7d8

/dev/mapper/mpathap3

Solution to the problem

You have to make sure that you have local disks that had been blacklisted. In this case, you can specify individual devices by their WWID (world-wide Identification) with the wwid entry in the blacklist section of the configuration file.

For example:

blacklist {

        wwid 3600508b1001030363945374330300f00

}

To verify the devices had been blacklisted you can use the command “multipath –v4” and you should see the output as below.

===== paths list =====

uuid                              hcil    dev  dev_t  pri dm_st chk_st vend/pr

3600508b1001030363945374330300f00 0:0:0:1 sda  8:0    1   undef ready  HP,LOGI

3600508b4000756cf0000a000029d0000 1:0:0:1 sdb  8:16   10  undef ready  HP,HSV2

.

.

May 06 23:01:06 | sda: (HP:LOGICAL VOLUME) vendor/product blacklisted

May 06 23:01:06 | sdb: (HP:HSV210) vendor/product blacklisted

.

.

Then, you have to recompile the initramdisk, to make sure that during the booting (init), the HP logical disk (local disk) is blacklisted.

1.       Backup your initial initramdisk

[root@s11t0008c boot]# cp -p /boot/initramfs-`uname -r`.img /boot/initramfs-`uname -r`.img.bak

2.       Generate the new initramdisk and reboot the server.

[root@s11t0008c boot]# mkinitrd –force /boot/initramfs-`uname -r`.img `uname -r`

[root@s11t0008c boot]# init 6

Post configuration/verification

Once you are done with the reboot, you should see this.

[root@s11t0008c ~]# df -h

Filesystem            Size  Used Avail Use% Mounted on

/dev/sda3            1008M  459M  499M  48% /

tmpfs                  32G     0   32G   0% /dev/shm

/dev/sda1             186M  168M  9.2M  95% /boot

/dev/mapper/vg00-home

                      4.0G  158M  3.6G   5% /home

/dev/mapper/vg00-opt  4.0G  1.7G  2.1G  45% /opt

/dev/mapper/vg00-tmp  4.0G  138M  3.7G   4% /tmp

/dev/mapper/vg00-usr  4.0G  1.3G  2.6G  33% /usr

/dev/mapper/vg00-var  4.0G  637M  3.2G  17% /var

/dev/mapper/vg00-crash

                      7.7G  923M  6.4G  13% /var/crash

tmpfs                 4.0K     0  4.0K   0% /dev/vx

[root@s11t0008c ~]# blkid -U e65ac106-53a5-4f0d-bd5e-ad563883c7d8

/dev/sda3

[root@s11t0008c ~]# mpathconf

multipath is enabled

find_multipaths is disabled

user_friendly_names is enabled

dm_multipath module is loaded

multipathd is chkconfiged on

[root@s11t0008c ~]# multipath -ll

[root@s11t0008c ~]#