ssh permission denied (publickey,keyboard-interactive)

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/
  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: MAC: <implicit> compression: none
  debug1: kex: server->client cipher: 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/
  debug1: fd 9 clearing O_NONBLOCK
  debug1: /data/data/ matching key found: RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0
  debug1: /data/data/ key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
  Accepted key RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0 found at /data/data/
  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/
  debug1: fd 9 clearing O_NONBLOCK
  debug1: /data/data/ matching key found: RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0
  debug1: /data/data/ key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
  Accepted key RSA SHA256:R9btL/xmY/LOZrXIoPjARJxTpAkWUyR4QB5bAIVlEh0 found at /data/data/
  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 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/
  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: MAC: <implicit> compression: none
  debug1: kex: server->client cipher: 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

1 Answer

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.