Troubles with OpenSSH

UNIX for Advanced & Expert Users
1

Hi,

I am trying to login from one AIX server to another without using a password, a basic configuration, however it doesn't seem to work.

All things are in place. I have both a public and private key in the ~/.ssh folder and also have an "authorized_keys" file on the target-server containing the pub-file. The permissions are also OK, the .ssh folders on both sides have 0700 permission. Both servers are also in each others reach, so no firewalls in between.

*A small note however. I do notice a difference after I renamed the private key. For instance, when creating the keys with "ssh-keygen -t dsa" the key's are named "id_dsa" & "id_dsa.pub". When keeping those names and trying to login to the other server I receive a "Connection closed by <IP-adres>" error. But when I rename the private key to for instance "openssh_serv1" that error is gone, but then it keeps on asking for a password. (So probably the server is expecting the private key to be named id_dsa?)

Whatever the case, I can't login without a password and I'm running out of idea's... (tried both rsa & dsa keys, tried adding a "authorization" file, tried several "no/yes" options in the /etc/ssh/sshd_config file, etc.)

Version of OpenSSH:

ssh -V
OpenSSH_5.2p1, OpenSSL 0.9.8k 25 Mar 2009

Verbose output

ssh -vvv serv2
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Failed dlopen: /usr/krb5/lib/libkrb5.a(libkrb5.a.so): 0509-022 Cannot load module /usr/krb5/lib/libkrb5.a(libkrb5.a.so).
0509-026 System error: A file or directory in the path name does not exist.

debug1: Error loading Kerberos, disabling Kerberos auth.
debug2: ssh_connect: needpriv 0
debug1: Connecting to servpacc [10.230.130.33] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /.ssh/identity type -1
debug1: identity file /.ssh/id_rsa type -1
debug3: Not a RSA1 key file /.ssh/id_dsa.
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
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.2
debug1: match: OpenSSH_5.2 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.2
debug2: fd 4 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-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
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,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib@openssh.com,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-group-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,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
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,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: none,zlib@openssh.com
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: 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: 132/256
debug2: bits set: 502/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /.ssh/known_hosts
debug3: check_host_in_hostfile: match line 1
debug3: check_host_in_hostfile: filename /.ssh/known_hosts
debug3: check_host_in_hostfile: match line 1
debug1: Host 'serv2' is known and matches the RSA host key.
debug1: Found key in /.ssh/known_hosts:1
debug2: bits set: 509/1024
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: /.ssh/identity (0)
debug2: key: /.ssh/id_rsa (0)
debug2: key: /.ssh/id_dsa (0)
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug3: start over, passed a different list publickey,password,keyboard-interactive
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: /.ssh/identity
debug3: no such identity: /.ssh/identity
debug1: Trying private key: /.ssh/id_rsa
debug3: no such identity: /.ssh/id_rsa
debug1: Trying private key: /.ssh/id_dsa
debug1: read PEM private key done: type DSA
debug3: sign_and_send_pubkey
debug2: we sent a publickey packet, wait for reply
Connection closed by <IP-adres>

Guidance would really be appreciated!
Thanks in advance!

2

Try setting the permissions on the authorized_keys file to 0600 instead. That is the recommended permissions for that file.

3

check the permissions of the home directory itself, once had a long troubleshoot because of that
wont work if the home directory is writeable by "others"

cheers

2 Likes
4

I did not know that.

That's seriously useful to know. Thank you!

5

Permissions need to be set like this:

.ssh - 600
authorized_keys - 644
(good idea sometimes to link authorized_keys to authorized_keys2 just in case it's looking for that file)

If still no luck its your sshd_config

/etc/ssh

check for this:

RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys
AuthorizedKeysFile ~/.ssh/authorized_keys

I've seen on some system they are commented out.

you may need to read in there to see what is commented and what is permitted to determine if that is the source of your problem....

Very rear but has happened i've seen openssh version mismatch and fixing that fixed the problem.

also you may want to use it like this:

ssh -v <hostname> -l <user>

to get a more detailed output if it is trying to look in the correct directory for .ssh

from the looks of it your going in as root and the /.ssh is not reading

Compare your rsa and dsa keys make sure they are the same... looks like the handshake fumbles.

debug2: we sent a publickey packet, wait for reply Connection closed by <IP-adres>

hope this helps!

6

Hi,

Thanks all for the answers! However, it still doesn't work for some reason. I've added the link to authorized_keys2 and I've rebuild the keys (am now using rsa keys). I've checked the sshd_config file and I've checked the permissions and all, but still I get the same error:

......
debug1: Offering public key: /.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
Connection closed by <IP-adress>

I even get the error when trying to ssh to itself:

root@servr1:/etc/security # ssh -l root localhost
The authenticity of host 'localhost (127.0.0.1)' can't be established.
RSA key fingerprint is 59:0d:7f:e4:e2:17:ec:c7:8c:0d:90:0b:37:3a:c1:11.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
Connection closed by 127.0.0.1

I've tried it on 3 servers already and everywhere I get the same result.