SSH still asks for password even after adding key to authorized_keys

ssh authentication ssh-keys

Here are the steps I did on my local computer:

ssh-keygen -t rsa
cat ~/.ssh/id_rsa | ssh [email protected] -p 1234 "cat > ~/.ssh/authorized_keys"

When I do a ssh [email protected] -p 1234 it still asks for the password :o

[email protected]'s password:

Why is it so? I already added it to the authorized keys but it still asks for the password. sshd_config:

Port 1234
Protocol 2
SyslogFacility AUTHPRIV
PubkeyAuthentication yes
AuthorizedKeysFile      .ssh/authorized_keys
PasswordAuthentication yes
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
GSSAPICleanupCredentials yes
UsePAM no
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS
Subsystem       sftp    /usr/libexec/openssh/sftp-server

Here's the result with -vvv:

$ ssh [email protected] -p 1234 -vvv
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
debug2: ssh_connect: needpriv 0
debug1: Connecting to remotehost.com [12.123.123.123] port 1234.
debug1: Connection established.
debug1: identity file /c/Documents and Settings/user/.ssh/identity type -1
debug3: Not a RSA1 key file /c/Documents and Settings/user/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /c/Documents and Settings/user/.ssh/id_rsa type 1
debug1: identity file /c/Documents and Settings/user/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.6
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-g
roup-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour1
28,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-c
tr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour1
28,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-c
tr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@open
ssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@open
ssh.com,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: diffie-hellman-group-exchange-sha256,diffie-hellman-g
roup-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour12
8,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rij
[email protected]
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour12
8,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rij
[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_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_init: found hmac-md5
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug2: dh_gen_key: priv key bits set: 135/256
debug2: bits set: 519/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: put_host_port: [12.123.123.123]:1234
debug3: put_host_port: [remotehost.com]:1234
debug3: check_host_in_hostfile: filename /c/Documents and Settings/user/.ss
h/known_hosts
debug3: check_host_in_hostfile: match line 1
debug3: check_host_in_hostfile: filename /c/Documents and Settings/user/.ss
h/known_hosts
debug3: check_host_in_hostfile: match line 1
debug1: Host '[remotehost.com]:1234' is known and matches the RSA host key.
debug1: Found key in /c/Documents and Settings/user/.ssh/known_hosts:1
debug2: bits set: 515/1024
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: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /c/Documents and Settings/user/.ssh/identity (0x0)
debug2: key: /c/Documents and Settings/user/.ssh/id_rsa (0xa01a418)
debug2: key: /c/Documents and Settings/user/.ssh/id_dsa (0x0)
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mi
c,password
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-m
ic,password
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: Trying private key: /c/Documents and Settings/user/.ssh/identity
debug3: no such identity: /c/Documents and Settings/user/.ssh/identity
debug1: Offering public key: /c/Documents and Settings/user/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mi
c,password
debug1: Trying private key: /c/Documents and Settings/user/.ssh/id_dsa
debug3: no such identity: /c/Documents and Settings/user/.ssh/id_dsa
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:

Solution 1:

~/.ssh must be chmod 700 and ~/.ssh/authorized_keys must be chmod 600. Both must be owned by you.

SSH will silently fall back on password login if those files/directories are more permissive although, from memory, it does log something about a "bad mode".

Also, check that ~/.ssh/authorized_keys actually contains something. I have a feeling that command may have created an empty file. The one I think you want is:

cat ~/.ssh/id_rsa.pub | ssh [email protected] -p 1234 "cat - > ~/.ssh/authorized_keys"

Solution 2:

As Ladadadada noted, you have:

cat ~/.ssh/id_rsa | ssh [email protected] -p 1234 "cat > ~/.ssh/authorized_keys"

This is copying out your private/public key pair to the authorized_keys file. Your authorized_keys file on the server should not have the private key. I would suggest the following:

  • Delete the authorized_keys file on the remote system entirely.
  • Temporarily change the permissions to .ssh to make it writeable if it hasn't already been done.
  • On your local system, navigate to the .ssh directory and ensure you have an id_rsa and id_rsa.pub file. the ssh-keygen command should have created both files for you
  • Execute the command Ladadadada provided:

cat ~/.ssh/id_rsa.pub | ssh [email protected] -p 1234 "cat - > ~/.ssh/authorized_keys"

Note: this should write your public key to the authorized_keys file. Double check to make sure your local copy of id_rsa.pub matches the key in the authorized_keys file.

The content of your id_rsa.pub key will look similar to (clipped a portion for brevity):

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDLrS9t0lEdxk52v8Jt/EJMNm9::::clipped:::::wu1WzNCvrkUDnqS/aQZJ4rR4J+GoMLxP2NT you@somehostname

This key, id_rsa.pub, should match the ssh key in the known_hosts file.

edited: fixed an error in a filename. I upvoted Ladadadada's answer because he caught the issue but I don't think it was picked up on by the OP

Solution 3:

TL;DR

On Client side:

  • open configuration file /etc/ssh/ssh_config;
  • here look for PreferredAuthentications;
  • make sure password comes after publickey and not viceversa

In my case password was written before publickey, so ssh would prompt me for password even though I had copied my pub_key onto server.

This problem can be found out easily using verbose:

ssh -v compute@compute1 ... ... debug1: Authentications that can continue: publickey,password debug1: Next authentication method: password

As you can see password is chosen before trying to use publickey.

Edit /etc/ssh/ssh_config by moving password after publickey

PreferredAuthentications keyboard-interactive,publickey,password,hostbased,gssapi-with-mi

Now you can login without being prompt for pwd.

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