Just trying to get a basic setup of openSSH going on an Ubuntu box to work remotely. Main issue: RSA keys fail auth. ssh DOES work using the password for auth, but I would much rather limit it to only allow ssh keys for auth.
Note that I refer to desktop and laptop. Desktop: machine acting as server. Laptop: machine acting as client.
Things that I have tried:
- verifying permissions
- regenerating keys
- transferring public keys using ssh-copy-id and directly via copy and paste
- different client machines
- running restorecon -Rv ~/.ssh (even though most posts say this applies mainly to CentOS, may as well try everything)
- and a whole lot of googling that has led to here
The relevant things I can think to include are the -vvv when attempting to connect on the laptop, the permissions of ~/.ssh on both machines, sshd_config on desktop, relevant entries in var/log/auth.log on the desktop. Obviously, if there is anything else that I can include that could help anyone resolve this issue, I will gladly provide relevant info.
Here is the -vvv when trying to auth:
➜ /home/troy ≫ ssh -vvv -i .ssh/id_rsa .229 -p xxx40 OpenSSH_7.4p1, OpenSSL 1.0.2k 26 Jan 2017 debug1: Reading configuration data /etc/ssh/ssh_config debug2: resolving "xxx.xxx.xxx.229" port xxx40 debug2: ssh_connect_direct: needpriv 0 debug1: Connecting to xxx.xxx.xxx.229 [xxx.xxx.xxx.229] port xxx40. debug1: Connection established. debug1: identity file .ssh/id_rsa type 1 debug1: key_load_public: No such file or directory debug1: identity file .ssh/id_rsa-cert type -1 debug1: identity file /home/troy/.ssh/id_rsa type 1 debug1: key_load_public: No such file or directory debug1: identity file /home/troy/.ssh/id_rsa-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_7.4 debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.1 debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.1 pat OpenSSH* compat 0x04000000 debug2: fd 3 setting O_NONBLOCK debug1: Authenticating to xxx.xxx.xxx.229:xxx40 as 'lenny' debug3: put_host_port: [xxx.xxx.xxx.229]:xxx40 debug3: hostkeys_foreach: reading file "/home/troy/.ssh/known_hosts" debug3: record_hostkey: found key type ECDSA in file /home/troy/.ssh/known_hosts:5 debug3: load_hostkeys: loaded 1 keys from [xxx.xxx.xxx.229]:xxx40 debug3: order_hostkeyalgs: prefer hostkeyalgs: ,,,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521 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,,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c debug2: host key algorithms: ,,,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,,,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa debug2: ciphers ctos: ,aes128-ctr,aes192-ctr,aes256-ctr,,,aes128-cbc,aes192-cbc,aes256-cbc debug2: ciphers stoc: ,aes128-ctr,aes192-ctr,aes256-ctr,,,aes128-cbc,aes192-cbc,aes256-cbc debug2: MACs ctos: ,,,,,,,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: MACs stoc: ,,,,,,,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: compression ctos: none,,zlib debug2: compression stoc: none,,zlib debug2: languages ctos: debug2: languages stoc: debug2: first_kex_follows 0 debug2: reserved 0 debug2: peer server KEXINIT proposal debug2: KEX algorithms: ,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1 debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,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-sha2-256,hmac-sha2-512,hmac-sha1 debug2: MACs stoc: ,,,,,,,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: compression ctos: none, debug2: compression stoc: none, debug2: languages ctos: debug2: languages stoc: debug2: first_kex_follows 0 debug2: reserved 0 debug1: kex: algorithm: debug1: kex: host key algorithm: ecdsa-sha2-nistp256 debug1: kex: server->client cipher: MAC: <implicit> compression: none debug1: kex: client->server cipher: MAC: <implicit> compression: none debug3: send packet: type 30 debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug3: receive packet: type 31 debug1: Server host key: ecdsa-sha2-nistp256 SHA256:M57GEOh/5elIh2RU446bRCamJ21QosRFOYaYx8u5Za4 debug3: put_host_port: [xxx.xxx.xxx.229]:xxx40 debug3: put_host_port: [xxx.xxx.xxx.229]:xxx40 debug3: hostkeys_foreach: reading file "/home/troy/.ssh/known_hosts" debug3: record_hostkey: found key type ECDSA in file /home/troy/.ssh/known_hosts:5 debug3: load_hostkeys: loaded 1 keys from [xxx.xxx.xxx.229]:xxx40 debug3: hostkeys_foreach: reading file "/home/troy/.ssh/known_hosts" debug3: record_hostkey: found key type ECDSA in file /home/troy/.ssh/known_hosts:5 debug3: load_hostkeys: loaded 1 keys from [xxx.xxx.xxx.229]:xxx40 debug1: Host '[xxx.xxx.xxx.229]:xxx40' is known and matches the ECDSA host key. debug1: Found key in /home/troy/.ssh/known_hosts:5 debug3: send packet: type 21 debug2: set_newkeys: mode 1 debug1: rekey after 134217728 blocks debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug3: receive packet: type 21 debug1: SSH2_MSG_NEWKEYS received debug2: set_newkeys: mode 0 debug1: rekey after 134217728 blocks debug2: key: .ssh/id_rsa (0x55a0c58221f0), explicit, agent debug2: key: /home/troy/.ssh/id_rsa (0x55a0c582fe00), agent debug3: send packet: type 5 debug3: receive packet: type 7 debug1: SSH2_MSG_EXT_INFO received debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512> 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 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 RSA public key: .ssh/id_rsa debug3: send_pubkey_test debug3: send packet: type 50 debug2: we sent a publickey packet, wait for reply debug3: receive packet: type 51 debug1: Authentications that can continue: publickey debug1: Offering RSA public key: /home/troy/.ssh/id_rsa debug3: send_pubkey_test debug3: send packet: type 50 debug2: we sent a publickey packet, wait for reply debug3: receive packet: type 51 debug1: Authentications that can continue: publickey debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey). And here is ~/.ssh on the desktop:
lenny@Timubukuntu:~/.ssh$ ls -la total 12 drwx------. 2 lenny lenny 4096 Feb 27 21:49 . drwxr-x---. 21 lenny lenny 4096 Feb 27 22:16 .. -rw-------. 1 lenny lenny 1146 Feb 27 20:35 authorized_keys And the ~/.ssh on the laptop:
➜ /home/troy/.ssh ≫ ls -la total 20 drwx------ 2 troy users 4096 Feb 27 21:53 . drwx------ 30 troy users 4096 Feb 27 23:03 .. -rw------- 1 troy users 1679 Feb 27 20:32 id_rsa -rw-r--r-- 1 troy users 394 Feb 27 20:32 id_rsa.pub -rw-r--r-- 1 troy users 1416 Feb 27 15:13 known_hosts And the sshd_config on the desktop:
lenny@Timubukuntu:/etc/ssh$ cat sshd_config # Package generated configuration file # See the sshd_config(5) manpage for details # What ports, IPs and protocols we listen for Port xxx40 # Use these options to restrict which interfaces/protocols sshd will bind to #ListenAddress :: #ListenAddress 0.0.0.0 Protocol 2 # HostKeys for protocol version 2 HostKey /etc/ssh/ssh_host_rsa_key HostKey /etc/ssh/ssh_host_dsa_key HostKey /etc/ssh/ssh_host_ecdsa_key HostKey /etc/ssh/ssh_host_ed25519_key #Privilege Separation is turned on for security UsePrivilegeSeparation yes # Lifetime and size of ephemeral version 1 server key KeyRegenerationInterval 3600 ServerKeyBits 1024 # Logging SyslogFacility AUTH LogLevel INFO # Authentication: LoginGraceTime 120 PermitRootLogin prohibit-password StrictModes yes RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile home/lenny/.ssh/authorized_keys # Don't read the user's ~/.rhosts and ~/.shosts files IgnoreRhosts yes # For this to work you will also need host keys in /etc/ssh_known_hosts RhostsRSAAuthentication no # similar for protocol version 2 HostbasedAuthentication no # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication #IgnoreUserKnownHosts yes # To enable empty passwords, change to yes (NOT RECOMMENDED) PermitEmptyPasswords no # Change to yes to enable challenge-response passwords (beware issues with # some PAM modules and threads) ChallengeResponseAuthentication no # Change to no to disable tunnelled clear text passwords PasswordAuthentication no # Kerberos options #KerberosAuthentication no #KerberosGetAFSToken no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes # GSSAPI options #GSSAPIAuthentication no #GSSAPICleanupCredentials yes X11Forwarding yes X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes #UseLogin no #MaxStartups 10:30:60 #Banner /etc/issue.net # Allow client to pass locale environment variables AcceptEnv LANG LC_* Subsystem sftp /usr/lib/openssh/sftp-server # Set this to 'yes' to enable PAM authentication, account processing, # and session processing. If this is enabled, PAM authentication will # be allowed through the ChallengeResponseAuthentication and # PasswordAuthentication. Depending on your PAM configuration, # PAM authentication via ChallengeResponseAuthentication may bypass # the setting of "PermitRootLogin without-password". # If you just want the PAM account and session checks to run without # PAM authentication, then enable this but set PasswordAuthentication # and ChallengeResponseAuthentication to 'no'. UsePAM yes And here is the relevant info in /var/log/auth.log on the desktop:
Feb 27 22:52:31 Timubukuntu sshd[1901]: Connection closed by 67.20.206.135 port 36566 [preauth] 3 Answers
The home directory can't be writable by anyone but the user for key permissions to work. The file will be ignored otherwise
Try chown -R troy:troy /home/troy/
Also I think you are missing a / in this part of sshd_config
AuthorizedKeysFile home/lenny/.ssh/authorized_keys
In my case the issues was with the incorrect shell exec.
journalctl -f .... Feb 25 11:45:54 59a02b89e0f6 sshd[]: User user not allowed because shell /usr/bin/env /bin/bash does not exist .... Changed /etc/passwd file for that user
vi /etc/passwd .... user:x:1000:1000::/home/user:/bin/bash .... I had this problem on CentOS 7. I am a regular Debian-based Linux user so I was a fish out of the water. I noticed that in some of the servers it worked and in just one it didn't. The audit.log said nothing useful and the secure.log did not give anything either. I found that the only real difference was some security context differences on files and directories between those that worked and those that didn't. Get the security with
sudo ls -laZ <user-home>/.ssh
of the directory (I'm assuming a lot of defaults on sshd_config).
You should see some ssh_home_t and user_home_t attributes. If you don't, use the chcon command to add the missing attributes.
For example
home="$(getent passwd <user> | cut -d: -f6)" sudo chcon -R unconfined_u:object_r:ssh_home_t:s0 "$home".ssh sudo chcon unconfined_u:object_r:user_home_t:s0 "$home" In my case, my suspicion is that the user was created in a non standard way. His home was a directory in /var/lib.
