vagrant disable password authentication not working - ssh

Question

I have added a new user to the vagrant machine. And now I am trying to ssh into the vagrant with the new user using public key and without password.
The vagrant file is:
Vagrant.configure("2") do |config|
config.vm.box = "ubuntu/bionic64"
config.vm.network "private_network", ip: "192.168.33.30"
end
Then I logged into the vagrant machine by doing vagrant ssh.
And then this is how I have added the new user to the vagrant machine:
sudo adduser new_user --disabled-password
sudo su - new_user
mkdir .ssh
chmod 700 .ssh
touch .ssh/authorized_keys
chmod 600 .ssh/authorized_keys
Then I generated a new pair of public private key by doing
ssh-keygen -t rsa -b 2048 -C "email#example.com"
Then I copied the public key into the .ssh/authorized_keys file.
I have also modified the /etc/ssh/sshd_config by changing the following lines
PubkeyAuthentication yes
PasswordAuthentication no
ChallengeResponseAuthentication no
And then I try to ssh into the vagrant from my machine by doing
ssh new_user#192.168.33.30 -i ../ssh_keys/vagrant
But it is still asking for a password. How can I disable the password?
UPDATE
So, these are the logs:
ssh vagrant#192.168.33.30 -v
Logs:
OpenSSH_8.3p1, OpenSSL 1.1.1g 21 Apr 2020
debug1: Reading configuration data /c/Users/payam/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 192.168.33.30 [192.168.33.30] port 22.
debug1: Connection established.
debug1: identity file /c/Users/payam/.ssh/id_rsa type -1
debug1: identity file /c/Users/payam/.ssh/id_rsa-cert type -1
debug1: identity file /c/Users/payam/.ssh/id_dsa type -1
debug1: identity file /c/Users/payam/.ssh/id_dsa-cert type -1
debug1: identity file /c/Users/payam/.ssh/id_ecdsa type -1
debug1: identity file /c/Users/payam/.ssh/id_ecdsa-cert type -1
debug1: identity file /c/Users/payam/.ssh/id_ecdsa_sk type -1
debug1: identity file /c/Users/payam/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /c/Users/payam/.ssh/id_ed25519 type -1
debug1: identity file /c/Users/payam/.ssh/id_ed25519-cert type -1
debug1: identity file /c/Users/payam/.ssh/id_ed25519_sk type -1
debug1: identity file /c/Users/payam/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /c/Users/payam/.ssh/id_xmss type -1
debug1: identity file /c/Users/payam/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to 192.168.33.30:22 as 'vagrant'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:3jRn/OmhK6LmNBtpZbgjM64I1+lougeAppjUcJDtQXA
debug1: Host '192.168.33.30' is known and matches the ECDSA host key.
debug1: Found key in /c/Users/payam/.ssh/known_hosts:2
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: /c/Users/payam/.ssh/id_rsa
debug1: Will attempt key: /c/Users/payam/.ssh/id_dsa
debug1: Will attempt key: /c/Users/payam/.ssh/id_ecdsa
debug1: Will attempt key: /c/Users/payam/.ssh/id_ecdsa_sk
debug1: Will attempt key: /c/Users/payam/.ssh/id_ed25519
debug1: Will attempt key: /c/Users/payam/.ssh/id_ed25519_sk
debug1: Will attempt key: /c/Users/payam/.ssh/id_xmss
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /c/Users/payam/.ssh/id_rsa
debug1: Trying private key: /c/Users/payam/.ssh/id_dsa
debug1: Trying private key: /c/Users/payam/.ssh/id_ecdsa
debug1: Trying private key: /c/Users/payam/.ssh/id_ecdsa_sk
debug1: Trying private key: /c/Users/payam/.ssh/id_ed25519
debug1: Trying private key: /c/Users/payam/.ssh/id_ed25519_sk
debug1: Trying private key: /c/Users/payam/.ssh/id_xmss
debug1: Next authentication method: password
vagrant#192.168.33.30's password:
ssh vagrant#192.168.33.30 -i .vagrant/machines/automation_node/virtualbox/private_key -v
OpenSSH_8.3p1, OpenSSL 1.1.1g 21 Apr 2020
debug1: Reading configuration data /c/Users/payam/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 192.168.33.30 [192.168.33.30] port 22.
debug1: Connection established.
load pubkey ".vagrant/machines/automation_node/virtualbox/private_key": invalid format
debug1: identity file .vagrant/machines/automation_node/virtualbox/private_key type -1
debug1: identity file .vagrant/machines/automation_node/virtualbox/private_key-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to 192.168.33.30:22 as 'vagrant'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:3jRn/OmhK6LmNBtpZbgjM64I1+lougeAppjUcJDtQXA
debug1: Host '192.168.33.30' is known and matches the ECDSA host key.
debug1: Found key in /c/Users/payam/.ssh/known_hosts:2
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: .vagrant/machines/automation_node/virtualbox/private_key explicit
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: .vagrant/machines/automation_node/virtualbox/private_key
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: password
vagrant#192.168.33.30's password:
This is using a new pair of private/public key that I generated myself. The public key is added to /home/vagrant/.ssh/authorized_keys. And here I am providing the private key to ssh ssh vagrant#192.168.33.30 -i ../ssh_keys/vagrant_automation_node -v
OpenSSH_8.3p1, OpenSSL 1.1.1g 21 Apr 2020
debug1: Reading configuration data /c/Users/payam/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 192.168.33.30 [192.168.33.30] port 22.
debug1: Connection established.
debug1: identity file ../ssh_keys/vagrant_automation_node type 0
debug1: identity file ../ssh_keys/vagrant_automation_node-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to 192.168.33.30:22 as 'vagrant'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:3jRn/OmhK6LmNBtpZbgjM64I1+lougeAppjUcJDtQXA
debug1: Host '192.168.33.30' is known and matches the ECDSA host key.
debug1: Found key in /c/Users/payam/.ssh/known_hosts:2
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: ../ssh_keys/vagrant_automation_node RSA SHA256:jPKUlxB/TMj0TVOug3DVZZdwhC7eUz6/Zl3WGOCgQwY explicit
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering public key: ../ssh_keys/vagrant_automation_node RSA SHA256:jPKUlxB/TMj0TVOug3DVZZdwhC7eUz6/Zl3WGOCgQwY explicit
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: password
vagrant#192.168.33.30's password:
In all cases the authentication falls back to password.

Answer 1

In addition of adding -v, to check if ssh does take the right key, see if the following can help:
using ssh -i ../ssh_keys/vagrant new_user#192.168.33.30, to make sure the -i option is taken into account
make sure the public key was copied as one line in the vagrant remote machine ~new_user/.ssh/authorized_keys
make sure the private key is not passphrase protected (I generally make those with ssh-keygen -t rsa -b 2048 -C "email#example.com" -P "")
Since ssh vagrant#192.168.33.30 -i ../ssh_keys/vagrant_automation_node -v does not work, and if restarting the VM is not enough, activate the debug option on the sshd process
/usr/sbin/sshd -D -dd
# or
/usr/sbin/sshd -D -E /home/<user>/sshd.debug.log
# or
/usr/sbin/sshd -D -dd -f /home/<user>/sshd.debug.log
The goal is to check on the server side why your public key is rejected.
From the discussion, the OP Payam Mesgari confirms:
I found it...
Somehow there was an already existing network adapter on my PC which had the ip address 192.168.33.1 with subnet /24.
Meaning everytime I was trying to ssh into my vagrant machine which was given a static IP of 192.168.33.10, I was actually hitting the other network adapter.
That also explains why nothing was getting logged on the vagrant machine in the sshd...
Basically everytime I was doing anything with an IP address in the subnet 192.168.33.10/24 it was hitting my own adapter on windows, thus never even reached the VMs.
I changed the VMs IP addresses and now everything works