SSH with no password (passwordless) on Synology DSM 5 as other (non-root) user

ssh linux nas

I'm trying to ssh into my Synology disk station without a password (public key authentication), but as non-root.

When I try to ssh as root without password, it works. Following the exact same steps for another user doesn't work. It always asks for password (also, using a password works too).

I have followed every guide out there for this, but I think they're all for DSM 4.x rather than for the new 5.0 version.

SSH debug log

Here's the debug log when I try with -vvv flag:

aether@aether-desktop:~$ ssh -vvv [email protected]
OpenSSH_6.2p2 Ubuntu-6ubuntu0.2, OpenSSL 1.0.1e 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to aether-ds.local [192.168.2.149] port 22.
debug1: Connection established.
debug3: Incorrect RSA1 identifier
debug3: Could not load "/home/aether/.ssh/id_rsa" as a RSA1 public key
debug1: identity file /home/aether/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/aether/.ssh/id_rsa-cert type -1
debug1: identity file /home/aether/.ssh/id_dsa type -1
debug1: identity file /home/aether/.ssh/id_dsa-cert type -1
debug1: identity file /home/aether/.ssh/id_ecdsa type -1
debug1: identity file /home/aether/.ssh/id_ecdsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.2p2 Ubuntu-6ubuntu0.2
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.8p1-hpn13v11
debug1: match: OpenSSH_5.8p1-hpn13v11 pat OpenSSH_5*
debug2: fd 3 setting O_NONBLOCK
debug3: load_hostkeys: loading entries for host "aether-ds.local" from file "/home/aether/.ssh/known_hosts"
debug3: load_hostkeys: found key type RSA in file /home/aether/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],ssh-rsa
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: 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: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,[email protected],[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: kex_parse_kexinit: 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: kex_parse_kexinit: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: mac_setup: found hmac-md5
debug1: kex: server->client aes128-ctr hmac-md5 none
debug2: mac_setup: found hmac-md5
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: RSA f1:57:47:37:47:d4:5c:cd:a7:a4:5a:9c:a3:e8:1d:13
debug3: load_hostkeys: loading entries for host "aether-ds.local" from file "/home/aether/.ssh/known_hosts"
debug3: load_hostkeys: found key type RSA in file /home/aether/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys
debug3: load_hostkeys: loading entries for host "192.168.2.149" from file "/home/aether/.ssh/known_hosts"
debug3: load_hostkeys: found key type RSA in file /home/aether/.ssh/known_hosts:2
debug3: load_hostkeys: loaded 1 keys
debug1: Host 'aether-ds.local' is known and matches the RSA host key.
debug1: Found key in /home/aether/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/aether/.ssh/id_rsa (0x7f4ee2f47200),
debug2: key: /home/aether/.ssh/id_dsa ((nil)),
debug2: key: /home/aether/.ssh/id_ecdsa ((nil)),
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,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 RSA public key: /home/aether/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/aether/.ssh/id_dsa
debug3: no such identity: /home/aether/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/aether/.ssh/id_ecdsa
debug3: no such identity: /home/aether/.ssh/id_ecdsa: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
[email protected]'s password:

Any help appreciated.

Things I've tried so far

  • Check /etc/ssh/sshd_config (RSAAuthentication, PubkeyAuthentication, AuthorizedKeysFile).
  • Check .ssh/* perms and ownership. Tried several combinations.
  • Check HOME var in ~/.profile.
  • Restarted sshd via synoservicectl --restart sshd and by restarting whole NAS.

I had the same problem. I run an instance of sshd in debug mode on the DiskStation using "/usr/syno/sbin/sshd -d", then I connect to it using "ssh user@DiskSation -vvv" and I got the debug info on the server:

......

debug1: temporarily_use_uid: 1026/100 (e=0/0)

debug1: trying public key file /var/services/homes/user/.ssh/authorized_keys

debug1: fd 5 clearing O_NONBLOCK

Authentication refused: bad ownership or modes for directory /volume1/homes/user

......

I realized that the home folder needs the right permissions too:

cd /var/services/homes/
chown <username> <username>
chmod 755 <username>

And replace with the actual username, like "user".

Finally, the problem is solved!


you need to chmod your home directory to 755 (synology has it at 777 by default)

nas> ls -al
total 28
drwxrwxrwx  6 root     root  4096 2014-07-13 03:00 .
drwxr-xr-x 13 root     root  4096 2014-07-13 03:00 ..
drwxrwxrwx  3 admin    users 4096 2014-07-13 03:00 admin
...
nas> chmod 755 /home/admin
nas> ls -al
total 28
drwxrwxrwx  6 root     root  4096 2014-07-13 03:00 .
drwxr-xr-x 13 root     root  4096 2014-07-13 03:00 ..
drwxr-xr-x  3 admin    users 4096 2014-07-13 03:00 admin

As your permissions for .ssh and authorized_keys are set correct, just verify that the permissions to your home directory (/home/aether/) are set correctly (chmod 755 /home/aether/).

I could not log in with the default permissions (711) and it worked after changing the permissions.

Cheers Stephan


I had the same problem, double and triple checking all the above and still didn´t work. Finally, I realized that the ssh daemon was looking for the authorized_keys file in the wrong place, as there is no /home/nonrootuser directory.

You should create the path or make a symlink (those two options didn´t work for me), or what finally worked was to add those two lines in sshd_config file:

Match User nonrootuser
AuthorizedKeysFile      /var/services/homes/nonrootuser/.ssh/authorized_keys

This way, you make sure that the key you are adding via ssh-copy-id from the client is the same that the server (synology) is offering to stablish the connection for the nonrootuser.


Same problem here with dsm 6.0, solved thanks to this thread on Synology forums

It seems that user home permission are too much permissive ¿?¿??¿¿? 

chmod 755 /var/services/homes/[username]

...and now it works!

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