I have an AWS EC2 instance running. I was able to connect using my chomed (-r--------) keys using MobaXTerm and SSH (Ubuntu for Windows) (.pem key) and putty (.ppk key).I'm also working on the server using a IDL (Rstudio server), so the instance is running. At some point I couldn't connect again using Moba+Ssh+Putty, without making any change in keys or internal config commands on the instance.
These are the connection errors I got from those software (again, changing anyhong):
- MobaXterm:
Server refused our key --- No supported authentication methods available (server sent: publickey) - Putty:
Server refused our key --- No supported authentication methods available (server sent: publickey) - ssh:
Permission denied (publickey).
I saw some posts but they require to be connected to the server in order to modify files/permissions from inside. I can access some system files with the IDL (Rstudio) but as a particular user, not root.
Any ideas?
EDIT: Following @Jos suggestion, I used the -vv parameter. Here the answer
`
~$: ssh -vv -i "key.pem" ubuntu@ec2-ip.us-east-2.compute.amazonaws.comOpenSSH_8.2p1 Ubuntu-4ubuntu0.4, OpenSSL 1.1.1f 31 Mar 2020debug1: Reading configuration data /etc/ssh/ssh_configdebug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no filesdebug1: /etc/ssh/ssh_config line 21: Applying options for *debug2: resolving "ec2-ip.us-east-2.compute.amazonaws.com" port 22debug2: ssh_connect_directdebug1: Connecting to ec2-ip.us-east-2.compute.amazonaws.com [ip] port 22.debug1: Connection established.debug1: identity file key.pem type -1debug1: identity file key.pem-cert type -1debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4ubuntu0.4debug1: Remote protocol version 2.0, remote software version OpenSSH_8.9p1 Ubuntu-3ubuntu0.3debug1: match: OpenSSH_8.9p1 Ubuntu-3ubuntu0.3 pat OpenSSH* compat 0x04000000debug2: fd 3 setting O_NONBLOCKdebug1: Authenticating to ec2-ip.us-east-2.compute.amazonaws.com:22 as 'ubuntu'debug1: SSH2_MSG_KEXINIT sentdebug1: SSH2_MSG_KEXINIT receiveddebug2: local client KEXINIT proposaldebug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,ext-info-cdebug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,sk-ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256@openssh.com,ssh-ed25519,sk-ssh-ed25519@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsadebug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.comdebug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.comdebug2: 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-sha1debug2: 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-sha1debug2: compression ctos: none,zlib@openssh.com,zlibdebug2: compression stoc: none,zlib@openssh.com,zlibdebug2: languages ctos:debug2: languages stoc:debug2: first_kex_follows 0debug2: reserved 0debug2: peer server KEXINIT proposaldebug2: 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-sha256debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.comdebug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.comdebug2: 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-sha1debug2: 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-sha1debug2: compression ctos: none,zlib@openssh.comdebug2: compression stoc: none,zlib@openssh.comdebug2: languages ctos:debug2: languages stoc:debug2: first_kex_follows 0debug2: reserved 0debug1: kex: algorithm: curve25519-sha256debug1: kex: host key algorithm: ecdsa-sha2-nistp256debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: nonedebug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: nonedebug1: expecting SSH2_MSG_KEX_ECDH_REPLYdebug1: Server host key: ecdsa-sha2-nistp256 SHA256:5dFj4Av5Ln0oYtTRBYdcFKPe3hlTb5Fr9Q4Iok056UMdebug1: Host 'ec2-ip.us-east-2.compute.amazonaws.com' is known and matches the ECDSA host key.debug1: Found key in /home/user/.ssh/known_hosts:7debug2: set_newkeys: mode 1debug1: rekey out after 134217728 blocksdebug1: SSH2_MSG_NEWKEYS sentdebug1: expecting SSH2_MSG_NEWKEYSdebug1: SSH2_MSG_NEWKEYS receiveddebug2: set_newkeys: mode 0debug1: rekey in after 134217728 blocksdebug1: Will attempt key: key.pem explicitdebug2: pubkey_prepare: donedebug1: SSH2_MSG_EXT_INFO receiveddebug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com>debug1: kex_input_ext_info: publickey-hostbound@openssh.com (unrecognised)debug2: service_accept: ssh-userauthdebug1: SSH2_MSG_SERVICE_ACCEPT receiveddebug1: Authentications that can continue: publickeydebug1: Next authentication method: publickeydebug1: Trying private key: key.pemdebug2: we sent a publickey packet, wait for replydebug1: Authentications that can continue: publickeydebug2: we did not send a packet, disable methoddebug1: No more authentication methods to try.ubuntu@ec2-ip.us-east-2.compute.amazonaws.com: Permission denied (publickey).`