id_rsa.pub file SSH Error: invalid format

Question

My co worker and I have been trying to get my macbook to ssh into our AWS production server with no luck, this did work several months ago, but when we went to do it yesterday - we kept getting the following error message.

(I have replaced my username and hostname with a placeholder on all below sections)

$ ssh titan-data Load key "/Users/aronlilland/.ssh/id_rsa.pub": invalid format user@my_ip_address: Permission denied (publickey). 

Relavant config file data

<!-- config file --> Host titan-data     HostName my_ip_address     User user     IdentityFile ~/.ssh/id_rsa.pub     AddKeysToAgent yes 

I have gone through every step imaginable to get it working again, these are the following steps I have done in order:

Step 1) ensured that the .pub file was added on the server

this step was repeated several times, I regenerated my .pub file 4 times through out this process of elimination. The error seems to be something local though, not something from the server, someone will need to correct me if I am wrong.

Step 2) checked that the following folders and files have the correct permissions

drwx------    6 aronlilland  staff   192B Jan 18 09:41 .ssh/ 

drwx------    6 aronlilland  staff   192B Jan 18 09:41 ./ drwxr-xr-x+ 104 aronlilland  staff   3.3K Jan 16 16:09 ../ -rw-r--r--    1 aronlilland  staff   114B Jan 18 09:37 config -rw-------    1 aronlilland  staff   1.7K Jan 18 09:41 id_rsa -r--------@   1 aronlilland  staff   414B Jan 18 09:41 id_rsa.pub -rw-r--r--    1 aronlilland  staff   4.6K Jan 18 09:48 known_hosts 

this did not have any effect on fixing the error message.

Step 3) deleted my id_rsa file and id_rsa.pub file and regenerate a new one, having my coworker add the new .pub file to the server

1. first way i generated my keys ssh-keygen -t rsa -b 4096 -C "[email protected]" as suggested in the github documentation for generating a new SSH key
   • added the new pub file to the server through my co worker, did not work. still getting the same error.
2. Second way I generated my .pub file after deleting the old one, was to run ssh-keygen -t rsa as suggested in the joyent manually generating your ssh key on OSX documentation
   • still got the same error

Step 4) Upgraded ssh with homebrew

this was done following the documentation listed here, by Tim Hilliard

Step 5) deleted the ip address from my "known hosts" file (reaching for straws)

did not do anything, just had to confirm the IP address again.

Edit 1)

One thing I did do recently, and I remember seeing error messages during the installation, was I installed another version of python the other night, so there are two versions of python installed on my computer. Im not sure if this would cause any issues with ssh.

$ python -V Python 2.7.10 $ python3 -V Python 3.6.4 $ brew doctor Please note that these warnings are just used to help the Homebrew maintainers with debugging if you file an issue. If everything you use Homebrew for is working fine: please don't worry or file an issue; just ignore this.  Thanks!  Warning: Python is installed at /Library/Frameworks/Python.framework  Homebrew only supports building against the System-provided Python or a brewed Python. In particular, Pythons installed to /Library can interfere with other software installs. 

Edit 2)

added -v to ssh command, suggested by Alfabravo in comments

aronlilland:.ssh$ ssh titan-data -v OpenSSH_7.6p1, OpenSSL 1.0.2n  7 Dec 2017 debug1: Reading configuration data /Users/aronlilland/.ssh/config debug1: /Users/aronlilland/.ssh/config line 1: Applying options for titan-data debug1: Reading configuration data /usr/local/etc/ssh/ssh_config debug1: Connecting to my_ip_address [my_ip_address] port 22. debug1: Connection established. debug1: identity file /Users/aronlilland/.ssh/id_rsa.pub type 0 debug1: key_load_public: No such file or directory debug1: identity file /Users/aronlilland/.ssh/id_rsa.pub-cert type -1 debug1: Local version string SSH-2.0-OpenSSH_7.6 debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 pat OpenSSH* compat 0x04000000 debug1: Authenticating to my_ip_address:22 as 'user' debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: algorithm: [email protected] debug1: kex: host key algorithm: ecdsa-sha2-nistp256 debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ecdsa-sha2-nistp256 SHA256:2l8QDc7x/fyzshKaU32jj9MeFtMAccu25MZBFNQuStQ debug1: Host 'my_ip_address' is known and matches the ECDSA host key. debug1: Found key in /Users/aronlilland/.ssh/known_hosts:19 debug1: rekey after 134217728 blocks debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: rekey after 134217728 blocks debug1: SSH2_MSG_EXT_INFO received debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512> debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Offering public key: RSA SHA256:MuOjm+6gAzaxGr/n/If4LVjk/0H5/VT6zvib9/9C7c8 /Users/aronlilland/.ssh/id_rsa.pub debug1: Server accepts key: pkalg rsa-sha2-512 blen 279 Load key "/Users/aronlilland/.ssh/id_rsa.pub": invalid format debug1: No more authentication methods to try. user@my_ip_address: Permission denied (publickey). aronlilland:.ssh$  

Edit 3)

Checked to see if the .pub file is a valid format

aronlilland:.ssh$ ssh-keygen -l -f id_rsa.pub 2048 SHA256:MuOjm+6gAzaxGr/n/If4LVjk/0H5/VT6zvib9/9C7c8 [email protected] (RSA) aronlilland:.ssh$ touch foo.txt aronlilland:.ssh$ ls config       foo.txt      id_rsa       id_rsa.pub   known_hosts aronlilland:.ssh$ ssh-keygen -l -f foo.txt foo.txt is not a public key file. 

Edit 4)

Confirming that my id_rsa key and id_rsa.pub validate (I chopped off the end of my ssh-rsa key, there's no reason to include it on the web)

aronlilland:.ssh$ ssh-keygen -y -f id_rsa Enter passphrase:  ssh-rsa AAAAB3NzaC1yc2EAAAADAQA ....... 

Confirming permissions that updating file permissions did not change access (I tried 0444, 444, 0644, 644 just to be sure)

aronlilland:.ssh$ chmod 0444 id_rsa.pub aronlilland:.ssh$ ssh titan-data @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @         WARNING: UNPROTECTED PRIVATE KEY FILE!          @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Permissions 0444 for '/Users/aronlilland/.ssh/id_rsa.pub' are too open. It is required that your private key files are NOT accessible by others. This private key will be ignored. Load key "/Users/aronlilland/.ssh/id_rsa.pub": bad permissions user@my_ip_address: Permission denied (publickey). 

and the other

aronlilland:.ssh$ chmod 0644 id_rsa.pub aronlilland:.ssh$ ssh titan-data @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @         WARNING: UNPROTECTED PRIVATE KEY FILE!          @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Permissions 0644 for '/Users/aronlilland/.ssh/id_rsa.pub' are too open. It is required that your private key files are NOT accessible by others. This private key will be ignored. Load key "/Users/aronlilland/.ssh/id_rsa.pub": bad permissions user@my_ip_address: Permission denied (publickey). 

setting it back to chmod 400 id_rsa.pub

Edit 5)

running -vv

aronlilland:.ssh$ chmod 400 id_rsa.pub aronlilland:.ssh$ ssh titan-data -vv OpenSSH_7.6p1, OpenSSL 1.0.2n  7 Dec 2017 debug1: Reading configuration data /Users/aronlilland/.ssh/config debug1: /Users/aronlilland/.ssh/config line 1: Applying options for titan-data debug1: Reading configuration data /usr/local/etc/ssh/ssh_config debug2: resolving "my_ip_address" port 22 debug2: ssh_connect_direct: needpriv 0 debug1: Connecting to my_ip_address [my_ip_address] port 22. debug1: Connection established. debug1: identity file /Users/aronlilland/.ssh/id_rsa.pub type 0 debug1: key_load_public: No such file or directory debug1: identity file /Users/aronlilland/.ssh/id_rsa.pub-cert type -1 debug1: Local version string SSH-2.0-OpenSSH_7.6 debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 pat OpenSSH* compat 0x04000000 debug2: fd 3 setting O_NONBLOCK debug1: Authenticating to my_ip_address:22 as 'user' debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: local client KEXINIT proposal debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c debug2: host key algorithms: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: compression ctos: none,[email protected],zlib debug2: compression stoc: none,[email protected],zlib debug2: languages ctos:  debug2: languages stoc:  debug2: first_kex_follows 0  debug2: reserved 0  debug2: peer server KEXINIT proposal debug2: KEX algorithms: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1 debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: compression ctos: none,[email protected] debug2: compression stoc: none,[email protected] debug2: languages ctos:  debug2: languages stoc:  debug2: first_kex_follows 0  debug2: reserved 0  debug1: kex: algorithm: [email protected] debug1: kex: host key algorithm: ecdsa-sha2-nistp256 debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ecdsa-sha2-nistp256 SHA256:2l8QDc7x/fyzshKaU32jj9MeFtMAccu25MZBFNQuStQ debug1: Host 'my_ip_address' is known and matches the ECDSA host key. debug1: Found key in /Users/aronlilland/.ssh/known_hosts:19 debug2: set_newkeys: mode 1 debug1: rekey after 134217728 blocks debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug2: set_newkeys: mode 0 debug1: rekey after 134217728 blocks debug2: key: /Users/aronlilland/.ssh/id_rsa.pub (0x7fe9ff41c510), explicit debug1: SSH2_MSG_EXT_INFO received debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512> debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Offering public key: RSA SHA256:MuOjm+6gAzaxGr/n/If4LVjk/0H5/VT6zvib9/9C7c8 /Users/aronlilland/.ssh/id_rsa.pub debug2: we sent a publickey packet, wait for reply debug1: Server accepts key: pkalg rsa-sha2-512 blen 279 debug2: input_userauth_pk_ok: fp SHA256:MuOjm+6gAzaxGr/n/If4LVjk/0H5/VT6zvib9/9C7c8 Load key "/Users/aronlilland/.ssh/id_rsa.pub": invalid format debug2: we did not send a packet, disable method debug1: No more authentication methods to try. user@my_ip_address: Permission denied (publickey). 

Answer 1

The IdentityFile configuration parameter should be pointed at the private key which the SSH client uses to prove its identity to the remote server. (The remote server, then, should have the contents of id_rsa.pub installed in its authorized_keys file, or an equivalent location).

You should be putting the path to id_rsa, not id_rsa.pub, as an argument to IdentityFile in your ~/.ssh/config.

Answer 2

The following permissions should be set:

Private keys should get rw for owner, none for group, none for others:

chmod 600 id_rsa 

Public keys should get rw for owner, r for group, r for others:

chmod 644 id_rsa.pub