Client-side public key causing mess

Tue Apr 19 22:04:33 AEST 2016

Hello,

I have a client machine and a server machine. I generated a pair of
private-public rsa keys using ssh-keygen.

On the client-machine, I uploaded my private key onto ~/.ssh/id_rsa

On the server machine, I appended the content of the public key to
.ssh/authorized_keys

I can successfully connect from the client to the server with that config.

However, on the client-side, if I add a ~/.ssh/id_rsa.pub public key file
that doesn’t match  the private key file ~/.ssh/id_rsa, it will fail with
“Permission denied (publickey).”

Error on the server-side (sshd logs):

error: RSA_public_decrypt failed:
error:0407006A:lib(4):func(112):reason(106)

# openssl errstr 0407006A

error:0407006A:rsa routines:RSA_padding_check_PKCS1_type_1:block type is
not 01

It seems weird to me that a public key on the client side is taken into
account, when it works well without.

Linux distrib: CentOS 7

ssh version on the client side: OpenSSH_6.6.1p1, OpenSSL 1.0.1e-fips 11 Feb
2013

ssh version on the server side: OpenSSH_6.6.1p1, OpenSSL 1.0.1e-fips 11 Feb
2013

Full verbose output of ssh-client:

# ssh -vvv <server-ip>

OpenSSH_6.6.1, OpenSSL 1.0.1e-fips 11 Feb 2013

debug1: Reading configuration data /etc/ssh/ssh_config

debug1: /etc/ssh/ssh_config line 56: Applying options for *

debug2: ssh_connect: needpriv 0

debug1: Connecting to <server-ip> [<server-ip>] port 22.

debug1: Connection established.

debug1: permanently_set_uid: 0/0

debug3: Incorrect RSA1 identifier

debug3: Could not load "/root/.ssh/id_rsa" as a RSA1 public key

debug1: identity file /root/.ssh/id_rsa type 1

debug1: identity file /root/.ssh/id_rsa-cert type -1

debug1: identity file /root/.ssh/id_dsa type -1

debug1: identity file /root/.ssh/id_dsa-cert type -1

debug1: identity file /root/.ssh/id_ecdsa type -1

debug1: identity file /root/.ssh/id_ecdsa-cert type -1

debug1: identity file /root/.ssh/id_ed25519 type -1

debug1: identity file /root/.ssh/id_ed25519-cert type -1

debug1: Enabling compatibility mode for protocol 2.0

debug1: Local version string SSH-2.0-OpenSSH_6.6.1

debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1

debug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000

debug2: fd 3 setting O_NONBLOCK

debug3: load_hostkeys: loading entries for host "<server-ip>" from file
"/root/.ssh/known_hosts"

debug3: load_hostkeys: found key type ECDSA in file /root/.ssh/known_hosts:1

debug3: load_hostkeys: loaded 1 keys

debug3: order_hostkeyalgs: prefer hostkeyalgs:
ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384-cert-v01 at openssh.com,ecdsa-sha2-nistp521-cert-v01 at openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521

debug1: SSH2_MSG_KEXINIT sent

debug1: SSH2_MSG_KEXINIT received

debug2: kex_parse_kexinit:
curve25519-sha256 at libssh.org,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:
ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384-cert-v01 at openssh.com,ecdsa-sha2-nistp521-cert-v01 at openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01 at openssh.com,ssh-rsa-cert-v01 at openssh.com,ssh-dss-cert-v01 at openssh.com,ssh-rsa-cert-v00 at openssh.com,ssh-dss-cert-v00 at openssh.com,ssh-ed25519,ssh-rsa,ssh-dss

debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
aes128-gcm at openssh.com,aes256-gcm at openssh.com,chacha20-poly1305 at openssh.com
,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,
rijndael-cbc at lysator.liu.se

debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
aes128-gcm at openssh.com,aes256-gcm at openssh.com,chacha20-poly1305 at openssh.com
,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,
rijndael-cbc at lysator.liu.se

debug2: kex_parse_kexinit:
hmac-md5-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-ripemd160-etm at openssh.com,hmac-sha1-96-etm at openssh.com,hmac-md5-96-etm at openssh.com,hmac-md5,hmac-sha1,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96

debug2: kex_parse_kexinit:
hmac-md5-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-ripemd160-etm at openssh.com,hmac-sha1-96-etm at openssh.com,hmac-md5-96-etm at openssh.com,hmac-md5,hmac-sha1,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96

debug2: kex_parse_kexinit: none,zlib at openssh.com,zlib

debug2: kex_parse_kexinit: none,zlib at 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:
curve25519-sha256 at libssh.org,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,ecdsa-sha2-nistp256

debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
aes128-gcm at openssh.com,aes256-gcm at openssh.com,chacha20-poly1305 at openssh.com
,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,
rijndael-cbc at lysator.liu.se

debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
aes128-gcm at openssh.com,aes256-gcm at openssh.com,chacha20-poly1305 at openssh.com
,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,
rijndael-cbc at lysator.liu.se

debug2: kex_parse_kexinit:
hmac-md5-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-ripemd160-etm at openssh.com,hmac-sha1-96-etm at openssh.com,hmac-md5-96-etm at openssh.com,hmac-md5,hmac-sha1,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96

debug2: kex_parse_kexinit:
hmac-md5-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-ripemd160-etm at openssh.com,hmac-sha1-96-etm at openssh.com,hmac-md5-96-etm at openssh.com,hmac-md5,hmac-sha1,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hmac-md5-96

debug2: kex_parse_kexinit: none,zlib at openssh.com

debug2: kex_parse_kexinit: none,zlib at 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: setup hmac-md5-etm at openssh.com

debug1: kex: server->client aes128-ctr hmac-md5-etm at openssh.com none

debug2: mac_setup: setup hmac-md5-etm at openssh.com

debug1: kex: client->server aes128-ctr hmac-md5-etm at openssh.com none

debug1: kex: curve25519-sha256 at libssh.org need=16 dh_need=16

debug1: kex: curve25519-sha256 at libssh.org need=16 dh_need=16

debug1: sending SSH2_MSG_KEX_ECDH_INIT

debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

debug1: Server host key: ECDSA <fingerprint>

debug3: load_hostkeys: loading entries for host "<server-ip>" from file
"/root/.ssh/known_hosts"

debug3: load_hostkeys: found key type ECDSA in file /root/.ssh/known_hosts:1

debug3: load_hostkeys: loaded 1 keys

debug1: Host '<server-ip>' is known and matches the ECDSA host key.

debug1: Found key in /root/.ssh/known_hosts:1

debug1: ssh_ecdsa_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: /root/.ssh/id_rsa (0x7fb0334d5fd0),

debug2: key: /root/.ssh/id_dsa ((nil)),

debug2: key: /root/.ssh/id_ecdsa ((nil)),

debug2: key: /root/.ssh/id_ed25519 ((nil)),

debug1: Authentications that can continue: publickey

debug3: start over, passed a different list publickey

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: /root/.ssh/id_rsa

debug3: send_pubkey_test

debug2: we sent a publickey packet, wait for reply

debug1: Authentications that can continue: publickey

debug1: Trying private key: /root/.ssh/id_dsa

debug3: no such identity: /root/.ssh/id_dsa: No such file or directory

debug1: Trying private key: /root/.ssh/id_ecdsa

debug3: no such identity: /root/.ssh/id_ecdsa: No such file or directory

debug1: Trying private key: /root/.ssh/id_ed25519

debug3: no such identity: /root/.ssh/id_ed25519: No such file or directory

debug2: we did not send a packet, disable method

debug1: No more authentication methods to try.

Permission denied (publickey).

Elouan