Using PuTTY private key for new user on AWS EC2 Server

Question

I started an AWS EC2 instance. I can connect to my instance with the user ec2-user using the SSH private key generated by Amazon.

I followed the directions at: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/managing-users.html to add credentials for a new user "bob".

I created a new user bob, and generated a new public+private key set using PuTTY Key Generator. I moved the public key onto my EC2 instance at /home/bob/.ssh/authorized_keys

I changed the owner and group of /home/bob/.ssh and /home/bob/.ssh/authorized_keys to bob:bob

I changed the permissions of /home/bob/.ssh to 700

I changed the permissions of /home/bob/.ssh/authorized_keys to 600

When I try to SSH into my EC2 instance as bob, with bob's private key I git the error:

PuTTY Fatal Error
Disconnected: No supported authentication methods available (server sent: pulickey,gssapi-keyex,gssapi-with-mic)

The PuTTY console shows:

Using username "bob".
Server refused our key

I also tried from a command line to ssh into my EC2 instance with bob's private key, with no prevail. It didn't accept the key's passphrase. I also tried with a keypair that doesn't have a passphrase, but I was still prompted for a password and couldn't get on the server.

Here's my very verbose output

$ ssh -vvv -i bobs_key.ppk  [email protected]
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
debug2: ssh_connect: needpriv 0
debug1: Connecting to ec2-12-345-678-910.us-west-2.compute.amazonaws.com [12.345.678.910] port 22.
debug1: Connection established.
debug3: Not a RSA1 key file bobs_key.ppk.
debug2: key_type_from_name: unknown key type 'PuTTY-User-Key-File-2:'
debug3: key_read: missing keytype
debug2: key_type_from_name: unknown key type 'Encryption:'
debug3: key_read: missing keytype
debug2: key_type_from_name: unknown key type 'Comment:'
debug3: key_read: missing keytype
debug2: key_type_from_name: unknown key type 'Public-Lines:'
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
debug2: key_type_from_name: unknown key type 'Private-Lines:'
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
debug2: key_type_from_name: unknown key type 'Private-MAC:'
debug3: key_read: missing keytype
debug1: identity file bobs_key.ppk type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.4
debug1: match: OpenSSH_6.4 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-group-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,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,a
es256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,a
es256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,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-grou
p14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ecdsa-sha2-nistp256
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,[email protected],[email protected],aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,ae
s192-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,ae
s192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: [email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-512-etm@
openssh.com,[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,h
mac-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],hmac-sha2-512-etm@
openssh.com,[email protected],[email protected],[email protected],hmac-md5,hmac-sha1,[email protected],[email protected],hmac-sha2-256,h
mac-sha2-512,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: 140/256
debug2: bits set: 512/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /c/Users/bob/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 1
debug3: check_host_in_hostfile: filename /c/Users/bob/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 1
debug1: Host 'ec2-12-345-678-910.us-west-2.compute.amazonaws.com' is known and matches the RSA host key.
debug1: Found key in /c/Users/bob/.ssh/known_hosts:1
debug2: bits set: 501/1024
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: bobs_key.ppk (0x0)
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic
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: bobs_key.ppk
debug1: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
Enter passphrase for key 'bobs_key.ppk':
debug1: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
debug2: bad passphrase given, try again...
Enter passphrase for key 'bobs_key.ppk':
debug1: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
debug2: bad passphrase given, try again...
Enter passphrase for key 'bobs_key.ppk':
debug1: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
debug2: bad passphrase given, try again...
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

Putty log:

2015-02-08 08:35:15 Looking up host "ec2-12-345-678-910.us-west-2.compute.amazonaws.com"
2015-02-08 08:35:15 Connecting to 12.345.678.910 port 22
2015-02-08 08:35:15 Server version: SSH-2.0-OpenSSH_6.4
2015-02-08 08:35:15 Using SSH protocol version 2
2015-02-08 08:35:15 We claim version: SSH-2.0-PuTTY_Release_0.62
2015-02-08 08:35:15 Doing Diffie-Hellman group exchange
2015-02-08 08:35:15 Doing Diffie-Hellman key exchange with hash SHA-256
2015-02-08 08:35:16 Host key fingerprint is:
2015-02-08 08:35:16 ssh-rsa 2048 b6:76:a5:c6:06:dc:3c:d6:c2:65:fe:f5:55:27:b9:ef
2015-02-08 08:35:16 Initialised AES-256 SDCTR client->server encryption
2015-02-08 08:35:16 Initialised HMAC-SHA1 client->server MAC algorithm
2015-02-08 08:35:16 Initialised AES-256 SDCTR server->client encryption
2015-02-08 08:35:16 Initialised HMAC-SHA1 server->client MAC algorithm
2015-02-08 08:35:16 Reading private key file "C:\bob.ppk"
2015-02-08 08:35:16 Pageant is running. Requesting keys.
2015-02-08 08:35:16 Pageant has 1 SSH-2 keys
2015-02-08 08:35:16 Configured key file not in Pageant
2015-02-08 08:35:16 Offered public key
2015-02-08 08:35:16 Server refused our key
2015-02-08 08:35:16 Using SSPI from SECUR32.DLL
2015-02-08 08:35:16 Attempting GSSAPI authentication
2015-02-08 08:35:16 GSSAPI authentication request refused
2015-02-08 08:35:16 Disconnected: No supported authentication methods available (server sent: publickey,gssapi-keyex,gssapi-with-mic)

Server sshd log:

Feb  8 08:35:16 ip-101-10-101-1 sshd[3182]: error: Received disconnect from 22.33.44.555: 14: No supported authentication methods available [preauth]

Here's an example of the public key generated by PuTTY

---- BEGIN SSH2 PUBLIC KEY ----
Comment: "rsa-key-20150209"
AAAAB3NzaC1yc2EAAAABJQAAAQEAs2f7SVX8KOu0RvzQh0r6uwWS/TB5uXO7+QEs
CxF+0CF3vwLeOn+cNw1HQHy7EDHhGw4eYvL/ErbIyv4I8HgGe/IFe4qPUOMy3vtz
ZNjqemBsy32Lgsx/flQBYLW+XzYC4LeZv3TSZjfYyIk8ilRBOzdkP4CdYeK0rPRb
PPtlLQY5l95h1UnmuORNgA93yLqvKI/dSnkvKyTrJoCGbRXr5pept5Y9LSEHYlEa
drBpogsF9LYj/HDeaoIjBhGQu+CZRDzZSxgtv3+nePEkoeV1xC8tyJ83JiHcrX3P
bjouJHLLTWa2tl40XM913dkUSsbha2Fbd0wBchry9y2BlpUA9Q==
---- END SSH2 PUBLIC KEY ----

Here's an example of the private key to go along with it

PuTTY-User-Key-File-2: ssh-rsa
Encryption: aes256-cbc
Comment: rsa-key-20150209
Public-Lines: 6
AAAAB3NzaC1yc2EAAAABJQAAAQEAs2f7SVX8KOu0RvzQh0r6uwWS/TB5uXO7+QEs
CxF+0CF3vwLeOn+cNw1HQHy7EDHhGw4eYvL/ErbIyv4I8HgGe/IFe4qPUOMy3vtz
ZNjqemBsy32Lgsx/flQBYLW+XzYC4LeZv3TSZjfYyIk8ilRBOzdkP4CdYeK0rPRb
PPtlLQY5l95h1UnmuORNgA93yLqvKI/dSnkvKyTrJoCGbRXr5pept5Y9LSEHYlEa
drBpogsF9LYj/HDeaoIjBhGQu+CZRDzZSxgtv3+nePEkoeV1xC8tyJ83JiHcrX3P
bjouJHLLTWa2tl40XM913dkUSsbha2Fbd0wBchry9y2BlpUA9Q==
Private-Lines: 14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-MAC: 44a5eabcdebd7d33a1c99f72016563d26b435832

Solution 1

If you have pasted the public key to the authorized_keys file in the format shown in the question (---- BEGIN SSH2 PUBLIC KEY ----), it won't work.

You have to use the one-line format shown in PuTTYgen labeled "Public key for pasting into OpenSSH authorized_keys file".

It would be like:

rsa-key AAAAB3NzaC1yc2EAAAABJQAAAQEAs2f7SVX8KOu0RvzQh0r6uwWS/TB5uXO7+QEsCxF+0CF3vwLeOn+cNw1HQHy7EDHhGw4eYvL/ErbIyv4I8HgGe/IFe4qPUOMy3vtzZNjqemBsy32Lgsx/flQBYLW+XzYC4LeZv3TSZjfYyIk8ilRBOzdkP4CdYeK0rPRbPPtlLQY5l95h1UnmuORNgA93yLqvKI/dSnkvKyTrJoCGbRXr5pept5Y9LSEHYlEadrBpogsF9LYj/HDeaoIjBhGQu+CZRDzZSxgtv3+nePEkoeV1xC8tyJ83JiHcrX3PbjouJHLLTWa2tl40XM913dkUSsbha2Fbd0wBchry9y2BlpUA9Q== rsa-key-20150209

Solution 2

If you generated your private/public key in putty and directly copied them to your Linux distribution, the keys will be in Putty format. You will need to change it to OpenSSH format first before you can use it to connect to github or other server. Otherwise, it will give you an incorrect error and tell you that you need a passphrase.

Even though the private key may not have a .ppk file extension, it can still be in a putty format. You can open the file in notepad or other text editor to check the correct format.

OpenSSH format for public key

ssh-rsa AAAAB3NzaC1yc2EAAAA…

OpenSSH format for private key

-----BEGIN RSA PRIVATE KEY----- MIIEogIBAAKCAQEA4Jgy…

Newer OpenSSH format for private key

-----BEGIN OPENSSH PRIVATE KEY----- b3BlbnNzaC1rZXktdjEAA…

How to use generate key in OpenSSH format from putty:

If you are using ssh in Linux to log into another server or to log into github, you have to use the openssh format of the id. Steps:

1. In the start menu type Puttygen to open Puttygen. Then press Load or press Alt-l to load private key:

2. Convert putty private key to Open SSH format Conversions>Export OpenSSH key

3. Save key as id_rsa

4. If you are using Putty to log into linux and then ssh into another server, or ssh into github, copy the id_rsa to ~/.ssh/id_rsa

5. if it still doesn't work, follow the steps here: https://superuser.com/a/1285777/658319

Comments

[Martin Prikryl]

Can you share PuTTY's event log? And even better a corresponding snippet of SSH server's log? As to the ssh connection attempt: OpenSSH ssh client does not support PuTTY private key file format, you have to convert the key to OpenSSH format.

[Martin Prikryl]

How does your authorized_keys file look like with a public key generated by PuTTYgen?

[Boundless]

I added an example of both the private and public keys generated.

[Boundless]

That was the problem. I can't believe how much time I wasted trying to use the saved public key. Thank you for the help.

[trumpet205]

Putty can generate key that is usable on OpenSSH. After you generate the key in puttygen on the top it should say "Public Key for pasting into OpenSSH authorized_keys file". Simply copy that over to authorized_keys file.