Learning Linux: October 2016

Sunday, 23 October 2016

Unable to send mails from Linux servers

Here are the steps to configure sendmail .. In case if you notice the setup is missing on any of the servers..

keep these commands handy..

1. Backup sendmail.mc

cp -p /etc/mail/sendmail.mc /etc/mail/sendmail.mc_orig

2. Modify the external smtp server (uncommenting the line and updating the value )

dnl define(`SMART_HOST', `smtp.your.provider')dnl

define(`SMART_HOST', `mail.global.frontbridge.com')dnl

3. Compile

make all

4. Restart sendmail service

(OEL - 7)

systemctl start sendmail

systemctl enable sendmail

Lower versions

/etc/init.d/sendmail restart

(or)

/etc/init.d/sendmail start

Sunday, 9 October 2016

VirtualBOX error /tmp/vbox.0/Makefile.include.header:97: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=

During the installation of “Insert Guest Additions CD Image” everytime it was failing. The purpose of installing is will help us in free movement of cursor(mouse pointer) from host to guest and vice versa without using right CTRL key. Everytime if we want to move our cursor from guest to host or host to guest we need to press right CTRL key.

I am running my host on Windows7

and Guest running on OEL6.4

When i was installing i see below error:

When i checked the log file mention in the above screen, i see below error.

Creating udev rule for the Guest Additions kernel module.
/tmp/vbox.0/Makefile.include.header:97: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again. Stop.
Creating user for the Guest Additions.

To overcome this error update gcc using

1.yum update gcc

2. yum update

3. yum install kernel-uek-devel

*Please note that to execute “yum” your guest vmbox should have internet connection

now after doing all the above I again executed ./VMBoxLinuxAdditions.run

Yes I am able to successfully finish the Insert VMBox Guest Addition CD Image on Virtual Guest