Breaking a Bonded interface on RHEL

Today I had to break a bonded interface on a server running RHEL 5.  The bond was not a port channel but rather a fail-over setup.  The end result was to have only eth0 still up but if possible not bring down the box to do it.  Here's how I did it and a link to the original site I pulled it from.  You can also look in the documentation on the box if you don't have the interwebs available at the time.

RHEL Network Bonding

For more reference to use there values you can check, in your linux box :  /usr/share/doc/kernel-doc-2.6.18/Documentation/networking/bonding.txt 

>>>> 3.  How to Gracefully Break the Bonded Network Interface?

In Sample Configuration is we have bond0 configure for two interface name eth0 and eth1, and bond running configuration looks as 

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.4.0  Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 53:44:00:43:91:04
Slave Interface: eth1
MII Status: up
Link Failure Count: 0
Permanent HW addr: 52:33:00:6d:0e:70

The process to break the bonded interface is :

a.  Online remove one slave network interface which will be assigned with a new IP address from the bonding device. In this example, we are going to remove the eth1 from bond0. Execute the following command as root:

# ifenslave -d bond0 eth1
Or
# echo -eth1 > /sys/class/net/bond0/bonding/slaves

After issue the command above , You will see the eth1 device has been remove from bond0 # cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.4.0 
Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr:  53:44:00:43:91:04

b. Create a new network configuration for eth1 via graphic tool or text tool and then using following command to start eth1 again. Make sure the physical link has been changed correctly to match the new network configuration of eth1.

# ifup eth1
During the above 2 steps, the network of bond0 will work fine without any break up.

c. Create the same network configuration as bond0 for eth0 

 – just copy the content of /etc/sysconfig/network-scripts/ifcfg-bondX to  /etc/sysconfig/network-scripts/ifcfg-eth0, except the interface name and HW MAC address.

d. Remove the eth0 from bond0, destory the bond0 device and start eth0 immediately.

Please note this disruptive operation, The network of bond0/eth0 will break shortly during this step. # ifenslave -d bond0 eth0; ifdown bond0; ifup eth0
# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.4.0 
Bonding Mode: load balancing (round-robin)
MII Status: down
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
now ifconfig will show the configuration for only eth0 and eth1, no bonding interface appears.

e. Remove all bonding setting of bond0 in /etc/modprobe.conf and remove the ifcfg-bond0 in /etc/sysconfig/network-script directory. Then issue following command to remove the bond0 device from memory completely.

# echo -bond0 > /sys/class/net/bonding_masters

Updating iDRAC firmware from linux

Here are ways to update the firmware on Dell iDRAC6 remote access cards.

Both methods require downloading the BIOS from Dell and extracting it from the bundle. For example, this is the 1.70.21 firmware:
mkdir /tmp/dell
cd /tmp/dell
wget http://ftp.dell.com/esm/IDRAC6_FRMW_LX_R299265.BIN

Grab this and extract like this:
cd /tmp/dell
sh IDRAC6_FRMW_LX_R299265.BIN --extract ./idrac6-1.70.21
The firmware image is now in /tmp/dell/idrac6-1.70.21/payload/firmimg.d6

If using the CMC to update the firmware upload the extracted firmimg file, NOT THE BIN!

If you are just updating one machine, then the simplest way to perform the update is to use the Dell bmcfwul tool locally. This is supplied in the dell_ie_nitrogen package, and is installed to /usr/libexec/dell_dup/dell_ie_nitrogen/bmcfwul.

Install the new firmware like this:
/usr/libexec/dell_dup/dell_ie_nitrogen/bmcfwul -input=/tmp/dell/idrac6-1.70.21/payload/firmimg.d6
If you have several machines to update, the most convenient way to perform the update is with tftp.

First, copy the firmware image to the tftp server, and put it in /tftproot, or wherever the root of your tftp server is located:
scp /tmp/dell/idrac6-1.70.21/payload/firmimg.d6 $ip_of_tftp_server:/tftproot

Then, trigger a firmware upgrade on the machines remotely using either racadm or ssh:
racadm -r host.to.update -u root -p calvin fwupdate -g -u -a $ip_of_tftp_server
or
ssh host.to.update racadm fwupdate -g -u -a $ip_of_tftp_server

http://yo61.com/updating-dell-idrac6-firmware-linux.html

More on Sticky bits and ACLs

I'm going through the tedious task of hardening our Linux servers for an upcoming FSO visit as well as tweaking our existing kickstart for future builds.  A LOT of documentation goes into our kickstarts so we can pick things out and know what has been set and in response to which IAVA requirement.  I wanted a really clear example on how to properly use sticky bits and setfacl so to apply appropriate permissions when new files are created within a directory.  No point in setting the permissions on the current files if new ones can be created and bust the stig right?

The group ownership can be inherited by new files and folders created in your folder /path/to/parent by setting the setgid bit using chmod g+s like this:

chmod g+s /path/to/parent

Now, all new files and folder created under /path/to/parent will have the same group assigned as is set on /path/to/parent.

POSIX file permissions are not inherited; they are given by the creating process and combined with its current umask value.
However, you can use POSIX ACLs to achieve this. Set the default ACL on a directory:

setfacl -d -m u::rwX,g::rwX,o::- /path/to/parent

This will apply setfacl to the /path/to/parent directory, -modifying the -default ACLs – those that will be applied to newly created items. (Uppercase X means only directories will receive the +x bit.)

(If needed, you can add a u:someuser:rwX or g:someuser:rwX – preferably a group – to the ACLs.)

---

Note that, at least with ext3/ext4, you must mount the filesystem with the acl option, otherwise new ACLs cannot be set and existing ones will be ignored.

mount -o remount,acl /

Edit /etc/fstab to set this permanently.

Linux: sed command usage #1

I'm getting better with sed all the time but today was a challenging little booger.  I wanted to change /etc/pam.d/su from

cat /etc/pam.d/su
#%PAM-1.0
auth            sufficient      pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth           sufficient      pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
#auth           required        pam_wheel.so use_uid
auth            include         system-auth
account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet
account         include         system-auth
password        include         system-auth
session         include         system-auth
session         optional        pam_xauth.so

to

cat /etc/pam.d/su
#%PAM-1.0
auth            sufficient      pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth           sufficient      pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
auth           required        pam_wheel.so use_uid
auth            include         system-auth
account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet
account         include         system-auth
password        include         system-auth
session         include         system-auth
session         optional        pam_xauth.so

Notice the absense of the comment on line 6?  If you used sed -i 's/\#auth/auth/' <file> it would only look at the first line and then quit.  If you used sed -i 's/\#auth/auth/g' it'd change all of them.  I wanted to change just ONE out of the whole file.  The trick?  To specify a LINE for sed to work on.

sed -i '6s/\#auth/auth/' /etc/pam.d/su

Finally!  Looked for a while to find the answer.  The key is using the line number at the beginning of the search string here.  This link helped me get going in the right direction, http://www.linuxquestions.org/questions/linux-software-2/sed-display-text-on-specific-line-of-text-file-397405/. but it didn't give me EXACTLY what I wanted. However it helped me figure out how to specify a line.  I knew I could do it after I was able to print the line I wanted to work on.  SUCCESS!!

Need to make a Linux Kickstart iso?

I work with Linux on a daily basis.  I'm also fortunate to have a good grasp on how to build servers and most of my co-workers, aside from a few, have trusted me to make most of the servers.  It's a pain having to use a windows server just to mount the ISO to get the process started.  Also if you're working from a longer distance away the size of that ISO burdens your connection. Behold the necessary steps to make a tiny ISO of just what you need to get the process started!

http://mikent.wordpress.com/2012/04/12/how-to-create-a-kickstart-iso-boot-disk-for-redhat/

How to create a kickstart ISO boot disk for RedHat

1) logon as root
2) create a directory name bootdisk/RHEL
mkdir -p bootdisk/RHEL
3) copy the directory isolinux from your RedHat DVD or other location containing RedHat binaries in bootdisk/RHEL
example: cp -R /mnt/isolinux/* ~/bootdisk/RHEL/
4) change direcotry to ~/bootdisk/RHEL/
cd ~/bootdisk/RHEL/
5) create (or copy) your ks.cfg  (it will be discussed  later in another post how to create a kickstart file) in ~/bootdisk/RHEL/
example: cp ks.cfg ~/bootdisk/RHEL/
6) Now, you can create the ISO boot disk as follow (make sure you run the command from ~/bootdisk/RHEL/) :
mkisofs -r -T -J -V “RedHat KSBoot” -b isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -v -o linuxboot.iso .
7) Burn your iso linuxboot.iso into a blank cd-rom or mount it as it is on a Virtual Machine for example
8) At linux boot prompt, type the following command:
linux ks=cdrom:/ks.cfg
if you need to install using a specific IP address using a specific Ks boot device, type the following:
linux ks=cdrom:/ks.cfg append ip=<IPaddress> netmask=<netmask> ksdevice=<NICx>
example: linux ks=cdrom:/ks.cfg append ip=10.10.10.10 netmask=255.255.255.0 ksdevice=eth0
9) your are done!

Disabling Adobe Updates on a Mac

As a Mac admin I'm becoming increasingly aware of all the crap you have to do special to administer these things in an enterprise environment.  It's not as easy as Active Directory is with GPOs but rather it's more linux like since it is a Unix OS based on BSD.  I have some annoying updaters which try to update all the friggin time Adobe products.  Finally found a site which tells me how to do it, Stop Adobe Update Manager Launching.

Now I just need to test it for deployment using either Workgroup Manager or ARD.

Disable Adobe Update Manager

You need to create a file called com.adobe.AdobeUpdater.Admin.plist in your ~/Library/Preferences/ which can be done in two different ways, through the Terminal with a defaults write command, or by manually creating the file with a text editor.
Here’s how to do it through the command line:
* Launch Terminal (located in /Applications/Utilities/)
* At the command prompt, paste this command exactly
defaults write com.adobe.AdobeUpdater.Admin Disable.Update -bool yes
* Hit return to execute the command and create the plist file
You can double-check that the file has been created by looking in ~/Library/Preferences/ for the file. Now, theoretically at least, Adobe Update Manager will not launch on Mac user login and system boot.
There is also the option of manually creating the plist file, either though a plist editor or if you’re familiar with plists just by using a text editor.
Again you need to create a file located at /Library/Preferences with the name com.adobe.AdobeUpdater.Admin.plist with a boolean set true to “Disable.Update”, as you can see in the screenshot below:

Now you should be able to reboot your Mac, logout of a user, and anything as usual, without the annoyance of Adobe Update Manager barging in on your computing session. Stopped in it’s tracks!

Hacking RPMs

Ever want to modify a file within an RPM but you don't have the spec file or possibly even the source rpm?  Now you can!  And I've done it successfully using the link included as a guide along with the man page.

http://magazine.redhat.com/2007/12/04/hacking-rpms-with-rpmrebuild/

It's ultra cool!  I've successfully built a customized RPM build for a zabbix agent which has modifications allowing it to be used across ANY network you'd like to use including a modified .conf file :)  Oh the joys of linux.

Hacking RPMs with rpmrebuild

by afsilva

A couple of months ago, I discovered a tool called rpmrebuild while searching for a way to reverse engineer the files installed on an older Fedora system back into its original RPM package. Rpmrebuild is able to reconstruct an RPM by looking up the information about it on the RPM database that is part of every RPM-based distribution like Fedora.


But rpmrebuild doesn’t stop there; you can also modify actual RPM packages without needing access to its SRPMS or even knowing much about SPEC files. Although this may not be recommended when dealing with core/base Linux system RPMS, it is incredibly useful for developers, release engineers, and system administrators who needs to create internal RPMs for their organizations.

For example, it is common practice for release engineers to have a “back out strategy” in case a release does not meet requirements during installation. With rpmrebuild, the version and release numbers of an RPM that may be replaced by a new one can be tweaked so that in case there is a failure and the ”back out” RPM is needed, the release engineers can simply install the back out RPMs over the new RPMs. Then the back out RPMs will have higher version and/or release numbers on them, so a tool like up2date or yum can automatically pick up on the changes.

Rpmrebuild is currently available for Fedora 7 and 8. To install:

yum install rpmrebuild

To rebuild an installed package in your system into an RPM:

rpmrebuild packagename

While rebuilding a package, rpmrebuild will let you know if files have been modified from their original state.

If they have, it will give you the option to continue or halt the rebuilding of the package, and it will ask you if you want to change the release number of the package.
Example:

[root@dhcp227-94 SOURCES]# rpmrebuild httpd
Processing files: httpd-2.2.3-7.el5
Wrote: /usr/src/redhat/RPMS/i386/httpd-2.2.3-7.el5.i386.rpm
result: /usr/src/redhat/RPMS/i386/httpd-2.2.3-7.el5.i386.rpm

My favorite feature of rpmrebuild is the ability to modify its spec file on the fly. By that I mean that you can actually edit the spec of an existing RPM without having to rebuild from source. Why is this useful? Well, you can modify RPM package requirements, change logs, descriptions, and other fields on the spec without having to go through the entire build process again. It can save you a lot of time if you are in the business of building RPMs and don’t necessarily use auto-builders like koji or buildbot.

Here how’s it done:

rpmrebuild -e -p –no-test-install package.rpm

• -e tells rpmrebuild you want to edit the whole spec file
• -p is used because we are editing an actual RPM file
• –notest-install stops rpmrebuild from auto-testing your RPM, just in case you are building an RPM on a workstation that does not have all required RPMs for that package

Rpmrebuild also offers certain shortcuts and plugins. Below I will change the release number of an RPM file without having to open up its spec file. This is a great for automating release numbering processes.

[root@dhcp227-94 i386]# rpmrebuild --release=99 -p --notest-install httpd-2.2.3-7.el5.i386.rpm
Processing files: httpd-2.2.3-99
Wrote: /usr/src/redhat/RPMS/i386/httpd-2.2.3-99.i386.rpm
result: /usr/src/redhat/RPMS/i386/httpd-2.2.3-99.i386.rpm

Notice that the httpd package went from release #7 to #99.

Not as recommended, but useful for your organization’s internal applications, you can modify the version number of an RPM as well:

rpmrebuild --change-spec-preamble='sed -e "s/^Version:.*/Version:1\.3\.1\.0\.1/"' --release=99 -p –notest-install  some-package-1.3.1-11.noarch.rpm

This command will rebuild your RPM and produce some-package-1.3.1.0.1-99.noarch.rpm.
Some other things to keep in mind about rpmrebuild are:
1.Once an RPM is rebuilt, it will lose its original signature (if signed).
2.You need to be root to rebuild a package only if there are root-protected files in that package.
3.Rpmrebuild will respect your RPM “home” building location, so if you have .rpmmacros set up in your home dir, your rebuilt RPMs will show up there.

The authors of rpmrebuild, Eric Gerbier and Valery Reznic, point out that even though the newer versions of RPM have a repackage option, they still require the user to uninstall that package from their system, which sometimes is not necessarily easy because of the dependencies on that package.
If you want to rebuild an old RPM that is not easily available on the Internet anymore, or if you need to tweak packages for your organization’s internal releases, or even if all you want to do is study and learn a bit more about RPM packaging, rpmrebuild is a great tool to have.