traceroute

traceroute is a computer network diagnostic tool for displaying the route (path) and measuring transit delays of packets across an Internet Protocol (IP) network

traceroute example.com

vim

https://vimgifs.com/

https://linuxmoz.com/vi-commands-cheat-sheet/

u (undo)
control + r (redo)
dd  (delete the line)
/keyword (search word)
n (move forward to next search result)
N (move backward to previous search result)
:q! (discard change and quit)
:wq (save change and quit)

ssh

access the home directory

cd ~

create keygen

cd ~/.ssh/

ssh-keygen -t rsa

view keygen locally

less keyname
less keyname.pub

cat ~/.ssh/my_key.pub

vps routine

Log as root

ssh -i ~/.ssh/ my_key root@128.199.166.66

Check server status

top

htop is better one than just top

htop

apt-get install htop

htop

regular update (prefer once a week)

apt-get update

Monitor the latest log(Important for checking potential security issue)

tail the log file

sudo tail -f /var/log/auth.log

add user

adduser username

Grant user access

usermod -aG sudo username

Confirm the group is assigned

id -G -n username

Manage user

Change pwd

passwd username

switch user

su username

and

exit

Will be back to the root user.

sudo user access to visit file

cat /var/log/auth.log

It will go for permission denied

sudo !!

or

sudo cat /var/log/auth.log

ssh with the just created user

ssh username@128.199.166.66

If the console reports permission denied (publickey), please do following:

1. Open the ssh config

vim /etc/ssh/sshd_config

2. Modify below config

UsePAM yes
IgnoreUserKnownHosts no
PasswordAuthentication no

to

UsePAM no
IgnoreUserKnownHosts no
PasswordAuthentication yes

and save the change 3. restart ssh service

service ssh restart

Problem resolved! Let’s ssh again and login to the server now. But watch out, login server via the pwd is dangerous. Let introduce a much safer way below.

ssh server only with private key

It is much better secure comparing to just pwd.

cat my_key.pub | ssh username@128.199.166.66 "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

What did these lines do?

1. print public key
2. ssh to the server with the username
3. try to create .ssh folder
4. copy public key content to the authorized_keys file

And it might ask about the pwd.

Juts type in and hit enter.

Now login without pwd.

ssh -i ~/.ssh/my_key -p 1234 username@128.199.166.66

Disabled root auth and password auth for security

1. open the sshd_config

sudo vim /etc/ssh/sshd_config

2. change below two configs

PermitRootLogin yes
PasswordAuthentication yes

to

PermitRootLogin no
PasswordAuthentication no

Save the changes and quit 3. restart the service

sudo service ssh restart

Domain

1. buy a domain name. Of course!
2. setup 2 A Record. That means:

Type: choose 'A Record'
Host: one is '@', another is 'www'
value: 128.199.166.66

3. check the domain is mapping correctly

nslookup domain.com

It will list the domain info.

Prepare the server - Nginx

1. ssh to the server. Of course!
2. install Nginx

sudo apt-get install nginx

3. start the service

sudo service nginx start

Go and verify it via the domain or ip address 4. check the config

cat /etc/nginx/sites-available/default

or

less /etc/nginx/sites-available/default

Prepare the environment

1. install git

sudo apt-get install git

2. install nodejs and npm(And yes! NodeJs please. Not node!!!)

sudo apt-get install nodejs npm

3. Type node -v and see whether the env is in the node env. If it is not working, symlink nodejs to node using

sudo ln -s /usr/bin/nodejs /usr/bin/node

Setup www folder

1. Type below command.

sudo mkdir -p /var/www

2. Change ownership from root to the choose user

Before that, let’s see who is the owner of the folder.

ls -l /path/to/file/or/folder

Then.

sudo chown -R $USER:$USER /var/www

or specify user and group

sudo chown -R username:usergroup /var/www

Be careful with this command and only use it when the user really need the all the permission to one folder.

3. Cleanup the unused folders

rmdir tmp tmp2

or

rmdir tmp*

4. Correct the folder name

mv incorrectname correctname

Running the app automatically

pm2, nodemon, forever… Choose one and follow the instructions.