ssh permission denied (publickey,keyboard-interactive)

Question

Why I insist on asking a question

I've done a quick search on this problem and done a few solutions that have been said. None worked.

What I did

Termux as host. Installed apt install openssh, created publickey ssh-keygen with empty passphrase. And so I continued with cat id_rsa.pub >> authorized_keys. Tried ssh with ssh localhost -p 8022 -i id_rsa at host machine. No problem. But with ssh IP -p 8022 -i id_rsa at guest machine, no luck. I get Permission denied (publickey,keyboard-interactive)

sshd -d

• From host machine (success)

  $ sshd -d
  debug1: sshd version OpenSSH_7.8, OpenSSL 1.1.1  11 Sep 2018
  debug1: private host key #0: ssh-rsa SHA256:iFL8gWX/82tKCisCVLKZBNPOqjhCJkc7FsMnrpgnvLQ
  debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:e6xyxgJ4tsTWSgh/l8ugijsCnJNz10tc+CLtuLFiUvE
  debug1: private host key #2: ssh-ed25519 SHA256:5+j3igYvX5HjpIMV9OikSdhN9JxDzxhHkDfkA7huHp8
  debug1: rexec_argv[0]='/data/data/com.termux/files/usr/bin/sshd'
  debug1: rexec_argv[1]='-d'
  debug1: Bind to port 8022 on ::.
  Server listening on :: port 8022.
  debug1: Bind to port 8022 on 0.0.0.0.
  Server listening on 0.0.0.0 port 8022.
  debug1: Server will not fork when running in debugging mode.
  debug1: rexec start in 7 out 7 newsock 7 pipe -1 sock 10
  debug1: inetd sockets after dupping: 5, 5
  Connection from 127.0.0.1 port 54583 on 127.0.0.1 port 8022
  debug1: Client protocol version 2.0; client software version OpenSSH_7.8
  debug1: match: OpenSSH_7.8 pat OpenSSH* compat 0x04000000
  debug1: Local version string SSH-2.0-OpenSSH_7.8
  debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
  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: client->server cipher: [email protected] MAC: <implicit> compression: none
  debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
  debug1: expecting SSH2_MSG_KEX_ECDH_INIT
  debug1: rekey after 134217728 blocks
  debug1: SSH2_MSG_NEWKEYS sent
  debug1: expecting SSH2_MSG_NEWKEYS
  debug1: SSH2_MSG_NEWKEYS received
  debug1: rekey after 134217728 blocks
  debug1: KEX done
  debug1: userauth-request for user u0_a121 service ssh-connection method none
  debug1: attempt 0 failures 0
  Failed none for u0_a121 from 127.0.0.1 port 54583 ssh2
  debug1: userauth-request for user u0_a121 service ssh-connection method publickey
  debug1: attempt 1 failures 0
  debug1: userauth_pubkey: test pkalg rsa-sha2-512 pkblob RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0
  debug1: temporarily_use_uid: 10121/10121 (e=10121/10121)
  debug1: trying public key file /data/data/com.termux/files/home/.ssh/authorized_keys
  debug1: fd 9 clearing O_NONBLOCK
  debug1: /data/data/com.termux/files/home/.ssh/authorized_keys:2: matching key found: RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0
  debug1: /data/data/com.termux/files/home/.ssh/authorized_keys:2: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
  Accepted key RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0 found at /data/data/com.termux/files/home/.ssh/authorized_keys:2
  debug1: restore_uid: (unprivileged)
  Postponed publickey for u0_a121 from 127.0.0.1 port 54583 ssh2
  debug1: userauth-request for user u0_a121 service ssh-connection method publickey
  debug1: attempt 2 failures 0
  debug1: temporarily_use_uid: 10121/10121 (e=10121/10121)
  debug1: trying public key file /data/data/com.termux/files/home/.ssh/authorized_keys
  debug1: fd 9 clearing O_NONBLOCK
  debug1: /data/data/com.termux/files/home/.ssh/authorized_keys:2: matching key found: RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0
  debug1: /data/data/com.termux/files/home/.ssh/authorized_keys:2: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
  Accepted key RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0 found at /data/data/com.termux/files/home/.ssh/authorized_keys:2
  debug1: restore_uid: (unprivileged)
  debug1: auth_activate_options: setting new authentication options
  Accepted publickey for u0_a121 from 127.0.0.1 port 54583 ssh2: RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0
  debug1: active: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
  debug1: Entering interactive session for SSH2.
  debug1: server_init_dispatch
  debug1: server_input_channel_open: ctype session rchan 0 win 1048576 max 16384
  debug1: input_session_request
  debug1: channel 0: new [server-session]
  debug1: session_new: session 0
  debug1: session_open: channel 0
  debug1: session_open: session 0: link with channel 0debug1: session_open: session 0: link with channel 0
  debug1: server_input_channel_open: confirm session
  debug1: server_input_global_request: rtype [email protected] want_reply 0
  debug1: server_input_channel_req: channel 0 request pty-req reply 1
  debug1: session_by_channel: session 0 channel 0
  debug1: session_input_channel_req: session 0 req pty-req
  debug1: Allocating pty.
  debug1: session_pty_req: session 0 alloc /dev/pts/2
  debug1: server_input_channel_req: channel 0 request env reply 0
  debug1: session_by_channel: session 0 channel 0
  debug1: session_input_channel_req: session 0 req env
  debug1: server_input_channel_req: channel 0 request shell reply 1
  debug1: session_by_channel: session 0 channel 0
  debug1: session_input_channel_req: session 0 req shell
  Starting session: shell on pts/2 for u0_a121 from 127.0.0.1 port 54583 id 0
  debug1: Setting controlling tty using TIOCSCTTY.
  

• From guest machine (Permission denied)

  $ sshd -d
  debug1: sshd version OpenSSH_7.8, OpenSSL 1.1.1  11 Sep 2018
  debug1: private host key #0: ssh-rsa SHA256:iFL8gWX/82tKCisCVLKZBNPOqjhCJkc7FsMnrpgnvLQ
  debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:e6xyxgJ4tsTWSgh/l8ugijsCnJNz10tc+CLtuLFiUvE
  debug1: private host key #2: ssh-ed25519 SHA256:5+j3igYvX5HjpIMV9OikSdhN9JxDzxhHkDfkA7huHp8
  debug1: rexec_argv[0]='/data/data/com.termux/files/usr/bin/sshd'
  debug1: rexec_argv[1]='-d'
  debug1: Bind to port 8022 on ::.
  Server listening on :: port 8022.
  debug1: Bind to port 8022 on 0.0.0.0.
  Server listening on 0.0.0.0 port 8022.
  debug1: Server will not fork when running in debugging mode.
  debug1: rexec start in 7 out 7 newsock 7 pipe -1 sock 10
  debug1: inetd sockets after dupping: 5, 5
  Connection from 192.168.0.154 port 45802 on 192.168.0.197 port 8022
  debug1: Client protocol version 2.0; client software version OpenSSH_7.4p1 Debian-10+deb9u4
  debug1: match: OpenSSH_7.4p1 Debian-10+deb9u4 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: Local version string SSH-2.0-OpenSSH_7.8
  debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
  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: client->server cipher: [email protected] MAC: <implicit> compression: none
  debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
  debug1: expecting SSH2_MSG_KEX_ECDH_INIT
  debug1: rekey after 134217728 blocks
  debug1: SSH2_MSG_NEWKEYS sent
  debug1: expecting SSH2_MSG_NEWKEYS
  debug1: SSH2_MSG_NEWKEYS received
  debug1: rekey after 134217728 blocks
  debug1: KEX done
  debug1: userauth-request for user izzatnasrun service ssh-connection method none
  debug1: attempt 0 failures 0
  Failed none for izzatnasrun from 192.168.0.154 port 45802 ssh2
  debug1: userauth-request for user izzatnasrun service ssh-connection method keyboard-interactive
  debug1: attempt 1 failures 0
  debug1: keyboard-interactive devs
  debug1: auth2_challenge: user=izzatnasrun devs=
  debug1: kbdint_alloc: devices ''
  Failed keyboard-interactive for izzatnasrun from 192.168.0.154 port 45802 ssh2
  Connection closed by authenticating user izzatnasrun 192.168.0.154 port 45802
  debug1: do_cleanup
  

NOTE

• Permissions are as follows on host machine

  chmod 600 ~/.ssh/authorized_keys
  chmod 700 ~/.ssh
  chmod 700 ~
  

• Termux sshd is set 8022 as default

• Termux do not accept password so PasswordAuthentication no is a must

Solution

The public key should be created on the guest machine. So guest machine ssh-keygen and cat id_rsa.pub >> authorized_keys where id_rsa.pub is from guest machine and authorized_keys is on host machine.

Comments

[davidgo]

It sounds almost like you are confusing the host machine and your terminal, and that you have created the new id_rsa key on the host machine (which is probably not what you wanted to do). Can you be clearer as to where you have created what resources?

[eZeth]

Ahh I see. So you should create new id_rsa on guest machine and use the guest machine's public key on the ssh host machine.

[davidgo]

Yes. Pretending you did not own guest machines, the private key is private, so you create it on your system, then you give the public key to the server to provide access.