I have Ubuntu running on Windows (app) where I have created ssh key pair and added to Ubuntu server (Cloud) for the user.
Whenever I try to ssh from Ubuntu Sandbox (Windows) to ubuntu server (Cloud), authentication fails with following logs in /var/log/auth.log
Connection closed by #.#.#.# [preauth]
verbose logs for ssh are here from sandbox
$ ssh prod-bastion -vvv
OpenSSH_8.9p1 Ubuntu-3, OpenSSL 3.0.2 15 Mar 2022
debug1: Reading configuration data /home/jane/.ssh/config
debug1: /home/jane/.ssh/config line 1: Applying options for prod-bastion
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/home/jane/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/home/jane/.ssh/known_hosts2'
debug1: auto-mux: Trying existing master
debug1: Control socket "/home/jane/.ssh/jane@prod-bastion.example.net:22" does not exist
debug2: resolving "prod-bastion.example.net" port 22
debug3: resolve_host: lookup prod-bastion.example.net:22
debug3: ssh_connect_direct: entering
debug1: Connecting to prod-bastion.example.net [52.37.167.176] port 22.
debug3: set_sock_tos: set socket 3 IP_TOS 0x10
debug1: Connection established.
debug1: identity file /home/jane/.ssh/id_rsa type 0
debug1: identity file /home/jane/.ssh/id_rsa-cert type -1
debug1: identity file /home/jane/.ssh/id_ecdsa type -1
debug1: identity file /home/jane/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/jane/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/jane/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/jane/.ssh/id_ed25519 type -1
debug1: identity file /home/jane/.ssh/id_ed25519-cert type -1
debug1: identity file /home/jane/.ssh/id_ed25519_sk type -1
debug1: identity file /home/jane/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/jane/.ssh/id_xmss type -1
debug1: identity file /home/jane/.ssh/id_xmss-cert type -1
debug1: identity file /home/jane/.ssh/id_dsa type -1
debug1: identity file /home/jane/.ssh/id_dsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Ubuntu-3
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8
debug1: compat_banner: match: OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8 pat OpenSSH_6.6.1* compat 0x04000002
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to prod-bastion.example.net:22 as 'jane'
debug3: record_hostkey: found key type ED25519 in file /home/jane/.ssh/known_hosts:1
debug3: load_hostkeys_file: loaded 1 keys from prod-bastion.example.net
debug1: load_hostkeys: fopen /home/jane/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug3: order_hostkeyalgs: have matching best-preference key type ssh-ed25519-cert-v01@openssh.com, using HostkeyAlgorithms verbatim
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-c
debug2: host key algorithms: ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ssh-ed25519@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,rsa-sha2-512,rsa-sha2-256
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: host key algorithms: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr
debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr
debug2: MACs ctos: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: MACs stoc: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256@libssh.org
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: aes128-ctr MAC: umac-64-etm@openssh.com compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: umac-64-etm@openssh.com compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: Server host key: ssh-ed25519 SHA256:A1GFTbRvBgWebh+N7XxFam9Ke7QG731QdQRjwYXUbmo
debug3: record_hostkey: found key type ED25519 in file /home/jane/.ssh/known_hosts:1
debug3: load_hostkeys_file: loaded 1 keys from prod-bastion.example.net
debug1: load_hostkeys: fopen /home/jane/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
debug1: Host 'prod-bastion.example.net' is known and matches the ED25519 host key.
debug1: Found key in /home/jane/.ssh/known_hosts:1
debug3: send packet: type 21
debug2: ssh_set_newkeys: mode 1
debug1: rekey out after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: ssh_set_newkeys: mode 0
debug1: rekey in after 4294967296 blocks
debug1: Will attempt key: /home/jane/.ssh/id_rsa RSA SHA256:5ER+G702M2aLEQq4PP5a8opGM0W0ZLfhm2aHIbfxZpU
debug1: Will attempt key: /home/jane/.ssh/id_ecdsa
debug1: Will attempt key: /home/jane/.ssh/id_ecdsa_sk
debug1: Will attempt key: /home/jane/.ssh/id_ed25519
debug1: Will attempt key: /home/jane/.ssh/id_ed25519_sk
debug1: Will attempt key: /home/jane/.ssh/id_xmss
debug1: Will attempt key: /home/jane/.ssh/id_dsa
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/jane/.ssh/id_rsa RSA SHA256:5ER+G702M2aLEQq4PP5a8opGM0W0ZLfhm2aHIbfxZpU
debug1: send_pubkey_test: no mutual signature algorithm
debug1: Trying private key: /home/jane/.ssh/id_ecdsa
debug3: no such identity: /home/jane/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/jane/.ssh/id_ecdsa_sk
debug3: no such identity: /home/jane/.ssh/id_ecdsa_sk: No such file or directory
debug1: Trying private key: /home/jane/.ssh/id_ed25519
debug3: no such identity: /home/jane/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: /home/jane/.ssh/id_ed25519_sk
debug3: no such identity: /home/jane/.ssh/id_ed25519_sk: No such file or directory
debug1: Trying private key: /home/jane/.ssh/id_xmss
debug3: no such identity: /home/jane/.ssh/id_xmss: No such file or directory
debug1: Trying private key: /home/jane/.ssh/id_dsa
debug3: no such identity: /home/jane/.ssh/id_dsa: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
jane@prod-bastion.example.net: Permission denied (publickey).
What I am missing here ?
