PXE-M0F: Exiting Intel PXE ROM. Operating System Not Found"

 

While trying to add machines i was not able to boot the machines from the vmimages provided in the Datastore.

I tried multiple options like

1. F2—>change boot order –>CD rom first
2. Changed guest os to Windows/linux/solaris etc.
3. Tried to change boot options by delaying it to 10000 ms
4. Tried deleting and adding new machines and also tried to add local iso.

 

Finally i found out that the iso which were provided by vmware were corrupted and one of my damnsmalllinux.iso worked perfectly.

Please check your iso and try again.

“Too many open files “ error on weblogic or any other server

This usually happens because of lack of open file handles which we call as file descriptors.

On unix based systems current limits can be checked with ulimit –a

its defaulted to 1024.

For weblogic or servers you will have to change the default limit.

check current limits in /etc/security/limits.conf

Add the limit at user/group level here or set the limit in setDomainEnv.sh if your user has sudo or permission to change this parameter.

Adding ulimit –S –n XXX/ulimit –H –n XXX  at setDomainEnv.sh or CommonEnv.sh did not reflect the changes for me.

Its a good idea to set it in limits.conf file and restart all the services for that user.

Its advisable as per oracle docs to set hard limit to 65k.

Not able to ssh to a host any more

 

 

If you were able to login to a remote host and now its failing with errors like “ Remote host identification has changed”

“It is possible that someone is doing something nasty “

 

Just try to delete the known_hosts file in the

/home/%Userprofile%//.ssh/known_hosts

Make a backup by cp /path/filename /path/filename_backup before deleting

 

After deleting the known_hosts file you will be able to login

How to transfer data across virtual machines(virtual box/vmware) across different networks ?

To transfer data across multiple virtual machine lying in different netwoks and on different systems,
you can use the port forwarding feature in virtual machines.


click on port forwarding and set the incoming port of host and target port of the virtual machine.



here you can see if  a remote virtual machine v1 hosted on h1 wants to ssh to virtual machine v2 hosted on host h2
so it can do  ssh root@h2  -p 49837  and it will connect to V2 hosted on H2.
// easy way out –you can set incoming and outgoing both port as 22 if it is free and available to you.
I came across this problem specifically for moving docker images from one vm to another vm on different systems becuase for boot2docker image , the virtual box guest addition doesn’t work
Instead if you try to put guest addition on virtual box which is running docker, it stops booting and show a black screen.
// had to do another fix for it – revmove guestaddition iso from storage – in vm settings

Docker Basics -101

Docker is same like a virtual machine except it doesn’t have its on kernel and its container based.
Docker images can be built from docker files and deployed on multiple containers in same virtual machine.
Docker is more application oriented and doesn’t required seperate OS resources.

For windows docker can be installed by the docker toolkit which is a handle to docker virtual machine (default) which hots docker daemon.
$docker  // will give you all the options available to docker
even if you are on windows you can directly open the virtual box and login to the vm and execute your commands directly instead of using docker client.
To list images do
$docker images // –q for just ids/numerics
To save an image
docker save –o /path/imagename.tar  image-name ( i found repository name working here, the first column on list images screen)

here codenvy/che is the repository name

To move images between different systems , use scp

scp image.tar root@ip:location //
now go to target system and do
$docker load < image.tar

Grep doesn't work in solars

Try this

find . | xargs grep "keyworld" "path"

Continuous netstat also doesn't work on that so use script tag instead.



$ script  filename.txt // will start recording

do netstat or whatever

$exit
and your terminal output is recorded on the file , kool feature.

use nmap in kali linux

nmap -v -A -Pn hostname -oX path  for export

once results come  use xsltproc to convert xml to html

xsltproc source dest

how to use github

Open git bash - if on windows

Create a folder where you want to have your local repository.

$ git init // will create a .git file

$git config --global user.name "username"

$git config --global user.email "xxx@gmail.com"

$echo "# gold" >> README.md

$git init

$git add README.md

$git commit -m "first commit"

$git remote add origin https://github.com/username/gold.git

git push -u origin master