Adding a linux user/group and modifying user's primary group

Adding a linux user/group and modifying the primary group of the user.

Steps:

[root@localhost ~]# groupadd bigdata

[root@localhost ~]# grep -i bigdata /etc/group
bigdata:x:1001:
[root@localhost ~]#

[root@localhost ~]# useradd -m hadoop

[root@localhost ~]# id hadoop
uid=1001(hadoop) gid=1002(hadoop) groups=1002(hadoop)

[root@localhost ~]# ls -altr /home/hadoop
total 12
-rw-r--r--. 1 hadoop hadoop 231 Mar 31  2020 .bashrc
-rw-r--r--. 1 hadoop hadoop 193 Mar 31  2020 .bash_profile
-rw-r--r--. 1 hadoop hadoop  18 Mar 31  2020 .bash_logout
drwxr-xr-x. 4 root   root    35 Mar  1 02:00 ..
drwx------. 2 hadoop hadoop  62 Mar  1 02:00 .

[root@localhost ~]# usermod -g bigdata hadoop

[root@localhost ~]# ls -altr /home/hadoop
total 12
-rw-r--r--. 1 hadoop bigdata 231 Mar 31  2020 .bashrc
-rw-r--r--. 1 hadoop bigdata 193 Mar 31  2020 .bash_profile
-rw-r--r--. 1 hadoop bigdata  18 Mar 31  2020 .bash_logout
drwxr-xr-x. 4 root   root     35 Mar  1 02:00 ..
drwx------. 2 hadoop bigdata  62 Mar  1 02:00 .

[root@localhost ~]#

[root@localhost ~]# passwd hadoop
Changing password for user hadoop.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.
[root@localhost ~]#

<<<<<<<<<<< set a strong password

Now logged in as hadoop.

Last failed login: Mon Mar  1 02:06:41 EST 2021 from gateway on ssh:notty
Last login: Mon Mar  1 02:06:20 2021

[hadoop@localhost ~]$

[hadoop@localhost ~]$ ls -altr
total 16
-rw-r--r--. 1 hadoop bigdata 231 Mar 31  2020 .bashrc
-rw-r--r--. 1 hadoop bigdata 193 Mar 31  2020 .bash_profile
-rw-r--r--. 1 hadoop bigdata  18 Mar 31  2020 .bash_logout
drwxr-xr-x. 4 root   root     35 Mar  1 02:00 ..
-rw-------. 1 hadoop bigdata   5 Mar  1 02:06 .bash_history
drwx------. 2 hadoop bigdata  83 Mar  1 02:06 .
[hadoop@localhost ~]$

This closes this blog.Thanks

Vagrant box - authentication issues

Vagrant box - authentication issues

Box Os: Centos 7.9
Kernel: 3.10.0-1160.6.1.el7.x86_64

Symptoms:
1) Authentication Failure after setting up the box with insecure key on first reboot (vagrant halt/up/ssh). This is expected since the Vagrant will replace the insecure key on first boot.

    default: SSH auth method: private key
    default: Warning: Authentication failure. Retrying...
    default: Warning: Authentication failure. Retrying...

2) Even after generating a new key using the below method and copying the public key to the vagrant box the authorized_keys file will become zero bytes on restart (vagrant halt/up). This leads to authentication failure again.

$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/<useracnt>/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/<useracnt>/.ssh/id_rsa
Your public key has been saved in /home/<useracnt>/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:7KVti+u55MszInXV0py5gkjyAucdhfWoE3R5NtgqUcs <useracnt>@<machineid>
The key's randomart image is:
+---[RSA 3072]----+
|      .+++       |
|     .oo++=      |
|      .oE+.= o   |
|  . o ++. o *    |
|   + =o+So.. .   |
|    o =oo+. .    |
|     o .+ o.     |
|    . .+o+ .     |
|     . oX*.      |
+----[SHA256]-----+

3) We then set config.ssh.insert_key = false in Vagranfile, this ensures the authorized_keys arent replaced. But still we get encryption related error as below.

The private key you're attempting to use with this Vagrant box uses
an unsupported encryption type. The SSH library Vagrant uses does not support
this key type. Please use `ssh-rsa` or `ssh-dss` instead. Note that
sometimes keys in your ssh-agent can interfere with this as well,
so verify the keys are valid there in addition to standard
file paths.

4) We then generate rsa key with advanced option as below... which generated RSA 4096 instead of RSA 3072. We copy the public key using ssh-copy-id, still the encryption message is thrown.

$ ssh-keygen -t rsa -b 4096
Generating public/private rsa key pair.
Enter file in which to save the key (/home/<useracnt>/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/<useracnt>/.ssh/id_rsa
Your public key has been saved in /home/<useracnt>/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:hrSfT0367PoPlEMojHJZGJIbKdS9JadCDkdWiR2ayVs <useracnt>@<machineid>
The key's randomart image is:
+---[RSA 4096]----+
| ..o+B+=.        |
|  ooO=*=o  .     |
|   **oE*o . .    |
|    +*oo . . .   |
|    ..o S   =    |
|       o . = .   |
|        o o o    |
|         o o .   |
|          o+=..  |
+----[SHA256]-----+

Error:

The private key you're attempting to use with this Vagrant box uses
an unsupported encryption type. The SSH library Vagrant uses does not support
this key type. Please use `ssh-rsa` or `ssh-dss` instead. Note that
sometimes keys in your ssh-agent can interfere with this as well,
so verify the keys are valid there in addition to standard
file paths.

Now Solution:

5) Now after some search, we go through several solutions, none worked and I dont want to workaround the issue. Finally hit https://stackoverflow.com/questions/22922891/vagrant-ssh-authentication-failure solution offered by Sankari steps followed, it worked until resolving the encryption issue, one additional step as detailed below was needed for the fix.

    a. Generate the ssh-key pair fresh in the client centos machine...

[vagrant@localhost ~]$ ssh-keygen -t rsa -b 4096
Generating public/private rsa key pair.
Enter file in which to save the key (/home/vagrant/.ssh/id_rsa):
/home/vagrant/.ssh/id_rsa already exists.
Overwrite (y/n)? y
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/vagrant/.ssh/id_rsa.
Your public key has been saved in /home/vagrant/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:9FVGrkwfmAn7XD5jMBJ+tkG6C3zWLv4BcX/vlSkuYzI vagrant@localhost.localdomain
The key's randomart image is:
+---[RSA 4096]----+
|          o ..+  |
|         . * B   |
|        . * & +  |
|       o . # @ . |
|        S * B B .|
|         + + . ++|
|          o o. oo|
|         E =.....|
|          =.+.  .|
+----[SHA256]-----+

    b. Copy the public key to authorized_keys with 0600 permisson.
    c. Copy/Paste the private key to local cygwin64's .ssh/ directory.
    d. Try vagrant ssh now, it is still attempting to use the below private key [so the stackoverflow solution steps stop here]

debug1: Will attempt key: <windowsdrive>:/VBoxVms/vagrant_home/vcentos79_hivetest/.vagrant/machines/default/virtualbox/private_key  explicit

    e. Add the below config setting to Vagrantfile config.ssh.private_key_path = ['~/.ssh/id_rsa'], this seems to have done the trick.

debug1: Trying private key: <windowsdrive>:/cygwin64/home/<useracnt>/.ssh/id_rsa

    f. Now the vagrant ssh works fine.

debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
Last login: Mon Mar  1 01:01:08 2021 from gateway
[vagrant@localhost ~]$

    g. Try a vagrant halt/up. Should be fine.

$ vagrant halt
==> default: Attempting graceful shutdown of VM...
<useracnt>@<machineid> ~/dba/vcentos79_hivetest

$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Clearing any previously set forwarded ports...
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
==> default: Forwarding ports...
    default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 127.0.0.1:2222
    default: SSH username: vagrant
    default: SSH auth method: private key
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
==> default: Mounting shared folders...
    default: /vagrant => <windowsdrive>:/VBoxVms/vagrant_home/vcentos79_hivetest
==> default: Machine already provisioned. Run `vagrant provision` or use the `--provision`
==> default: flag to force provisioning. Provisioners marked to run always will still run.
<useracnt>@<machineid> ~/dba/vcentos79_hivetest

This closes this blog. Thank you for your visit.