Week 6 - Operating Systems in Practice.
Remote Access
1
Virtual Machines
2
Logging
3
Operating System Deployment
4
Event Viewer (Eventvwr.msc)
A GUI application that allows users to easily view and sort events recorded in the event log on a computer running a Windows-based operating system.
PuTTy
A free, open source software that you can use to make remote connection through several network protocols, including SSH.
Symantec Ghost
A populer commercial imaging tool is ..
Secure Shell (SSH) Protocol
A protocol for remote access to computers.
SCP (Secure Copy Protocol)
A protocol that uses SSH to securely copy files between a local and a remote host, or between two remote hosts. A command you can use in Linux to copy files between computers on a network. It utilizes SSH to transfer the data.
Virtual instance
A single virtual machine.
Remote connection
Allows us to manage multiple machines from anywhere in the world.
/var/log/auth.log
Authentication log Contains all events related to authentication for the local system
ssh cindy@ip
Connects through SSH.
log rotate
In Linux, the utility rotate logs is called
scp /home/cindy/Desktop/myfile.txt cindy@ip:
In this command, we run the SCP command with the path of the file we want to transfer to the user account, hostname, and path of where we want to copy the file to. The file is copied over. Super useful tool if you need to copy files to and from computers in a network.
/var/log
Logs in Linux are stored in this direcetory.
sudo du -a /home | sort -n -r | head -n 5
Luckily, Linux has an easy way to find the largest files on your file system. The du command can be used to list all files in a directory (recursively through subdirectories, too), which you can sort by size to find the largest files. By piping the output of du (using the "|" symbol) to the sort command, you can sort the output by file size. The "-n" and "-r" flags tell sort to treat the string output on each line as a number (the file size), and to sort in reverse order so that the largest files are listed first. By piping the output of this into the head command, you can print out only the top few results (you can specify how many to output by adding "-n [NUMBER]" to the end of the command). The command below uses du, sort, and head to show the top five largest files, starting from your /home directory:
1501538594
Mon Jul 31 15:03:14 PDT 2017
Centralized Logging
Multiple logs that are aggregated in a central location or centralized for consolidation.
service that the log event
Next up is the .. is referring to.
ls /var/log
On Linux machines, logs are stored in the /var/log directory. There are lots of log files in this directory, and you can view them with this command:
Clonezilla
One of the many disk cloning tools out there is the open source software.. It can be used to backup and restore a single machine or many machines simultaneously.
We can connect to SSH using passwords as you saw earlier but this is not super secure. The alternate is using
SSH authentication key. Keys comes in a set of private and public keys.
less /var/log/syslog | grep error
Shows the log results that have the word error in them.
Logging
The act of creating log events.
Time Stamp
The first field here when the event occured.
OpenSSH program
The most popular program to use SSH within Linux.
host name
The next field is the .. of the machine the event occurred on.
/var/log/syslog
The one log file that logs pretty much everything on your system. Will usually contain the most comprehensive information about your system.
RDP (Remote Desktop Protocol)
The protocol used by Microsoft's Terminal Set.vices implementations. Provides users with a graphical user interface to remote computers, provided the remote computer has enables RDP connections.
/var/log/dmesg
This file records information about what happened during boot up. system startup messages are logged here.
sudo dd if=/dev/sdd od=~/Desktop/my_usb_image.img bs=100m
This just says, I'm going to copy contents of /dev/SDD which is the USB drive and save it to the desktop in an image file. Once the image file is saved, we open it up we should see the exact same contents as the USB drive.
Microsoft Terminal Services Client (mstsc)
Used to create RDP connections to remote computers.
Plink or PuTTY Link
Used to make remote SSH connections.
VirtualBox
Used to manage virtual instances.
net share ShareMe=C:\Users\cindy\Desktop\ShareMe /grant:everyone,full
Users will be able to access the share folder by using the same methods we talked about before.
sudo cat /var/log/syslog
We're interested in syslog for the moment. The logs on Linux can be viewed like any text file; you can use the command below to view the contents of syslog:
Disk-to-disk cloning
Where you connect an external hard drive to the machine you want to clone. You can connect a a hard drive like your HDDs and SSDs into something known as an external hard drive dock.
sudo rm /home/lab/storage/ultra_mega_large.txt
You can see that the largest file in your home directory is /home/lab/storage/ultra_mega_large.txt, at about 5GB. This isn't an important file, but it's taking up a lot of space, so you can delete it to fix the disk space error:
PuTTY Secure Copy Client or pscp.exe
You can use it to copy files in a very similar way to Linux SCP command.
Shared folders
You tell windows you want to share a folder with a person or group of people, then drop some files into it.
How to read one line in sys log
and parse what it says.
putty.exe -ssh cindy@ip port
connects to ssh from command line.
pscp.ex C:\Users\cindy\Desktop\my_file.txt cind@ip:
copies this file to Linux work stations.
/admin
if you want to connect to the remote machine with administrative credentials.
/var/log/kern.log
kernel messages are logged here.
event that occured
last.
net share command
lets you do the same things as the GUI sharing workflow, and you'll need to specify what kind of permissions you'de like to give which users. Can also be used to list the currently shared folders on your computer by executing it without any arguments.
-ssh
tells putty.exe you want to connect via SSH.
tail -f /var/log/syslog
to keep the syst log file in an open window.
unmount /dev/sdd
unmounts the drive
