[SOLVED] connecting two linux boxes remotely

Turbocapitalist · 02-02-2019, 01:01 PM

If you do not have a key file which ssh-copy-id's -i points to then you'll get the "No such file ... look at the -f option" error.

The -i used with ssh-copy-id has to match the -f from ssh-keygen as used when creating the key pair

Code:

ssh-keygen -t ed25519 -f /path/box-a-key-ed25519 -C 'from desktop'
ssh-copy-id -i /path/box-a-key-ed25519 to box_A_@192.168.0.xxx

michaelk · 02-02-2019, 01:41 PM

You don't need to use the ssh-copy-id program if your physically at the server.

Code:

cat id_rsa.pub >> ~/.ssh/authorized_keys

Replace the name of the public key filename if different.

ssh-copy-id program basically logs into the server and then appends the public key to authorized_keys file. The cat command does the same thing but you do not need ssh.

however · 02-02-2019, 02:51 PM

Quote:

Originally Posted by michaelk

You don't need to use the ssh-copy-id program if your physically at the server.

Code:

cat id_rsa.pub >> ~/.ssh/authorized_keys

Replace the name of the public key filename if different.

ssh-copy-id program basically logs into the server and then appends the public key to authorized_keys file. The cat command does the same thing but you do not need ssh.

grrr... i had thought of this (i saw that the "id_rsa.pub" file only contained the encryption code) and then between jobs and tasks i totally forgot.

I guess you never stop learning from mistakes.

Thank you.

p.s.: i think i will test the ssh connection between box A and B tomorrow and let you know

however · 02-02-2019, 03:20 PM

Just a quick THANK YOU note, on the config file trick!
it works great now, after the correction and i can ssh box C directly by using just the host name (much easier/simpler that having to type the IP every time).
Question: can i have a config file that looks like this?

Code:

Host box_c
        HostName box_C_IP_address
        User darkstar
        IdentitiesOnly yes
        IdentityFile ~/.ssh/id_rsa 
        AddKeysToAgent ask

Host box_A
        HostName box_A_public_IP_address
        User darkstar
        IdentitiesOnly yes
        IdentityFile ~/.ssh/id_rsa 
        AddKeysToAgent ask

box A, would be on a different network

michaelk · 02-02-2019, 03:33 PM

Yes, make sure you specify the correct private key for each host if different.
Don't forget to forward the port on your work router to you work computer ip address. You have never posted your work network hardware or maybe you have an IT employee that can do it for you.

If you don't have a static work ip address you can sign up for a free dynamic dns service that will provide a url that always resolves to your ip address.

however · 02-03-2019, 03:57 PM

Quote:

Originally Posted by michaelk

make sure you specify the correct private key for each host if different.

done

Quote:

Don't forget to forward the port on your work router to you work computer ip address.

done

Quote:

You have never posted your work network hardware or maybe you have an IT employee that can do it for you.

Network hardware? not sure what i should post: card type? name? (no IT employee) - It just an old desktop running slackware 14.1 (so old that it doesnt have a network card; I use a wireless USB)

Quote:

If you don't have a static work ip address you can sign up for a free dynamic dns service that will provide a url that always resolves to your IP address.

is this safe? would it not be safer to ask for a static IP address to my ISP?

I will check connection tomorrow.

michaelk · 02-03-2019, 05:09 PM

As far as I know it isn't less safe. There will still be people scanning IP addresses including yours looking for vulnerabilities and ssh servers trying to break in using common usernames and passwords which is why disabling password authentication is important.

however · 02-04-2019, 08:33 AM

trying to connect from work, box A, i get:

Code:

bash-4.2$ ssh home_desktop 
/home/user/.ssh/config: line 6: Bad configuration option: addkeystoagent
/home/user/.ssh/config: terminating, 1 bad configuration options
bash-4.2$

my confirg file on box A is

Code:

Host home_desktop
        HostName box_B_public_IP
        User box_B_user			
        IdentitiesOnly yes
        IdentityFile /home/darkstar/.ssh/id_rsa
        AddKeysToAgent ask

suggestions?

michaelk · 02-04-2019, 08:40 AM

It depends on the ssh version running on the computer. Just remove the option for now.

however · 02-06-2019, 04:38 AM

Quote:

Originally Posted by michaelk

It depends on the ssh version running on the computer. Just remove the option for now.

Code:

bash-4.2$ ssh -V
OpenSSH_6.3p1, OpenSSL 1.0.1e 11 Feb 2013

(option removed)

I've had internet issues at work (ISP problems) and now i am back testing the ssh connection between box A and B (on two different networks).

when I ssh home_desktop, i get this msg:

Code:

bash-4.2$ ssh home_desktop
Permission denied (publickey,keyboard-interactive).

I have commented out "# PasswordAuthentication" for testing ssh on localhost and it gets connected OK. However, if i uncomment "PasswordAuthentication" it gives me the same error msg when i try to connect to localhost

Code:

bash-4.2$ ssh localhost
Permission denied (publickey,keyboard-interactive).

What else am i missing?

michaelk · 02-06-2019, 04:48 AM

Check permissions of keys. Use -v option with ssh commands to help debug.

Did you change anything?

however · 02-06-2019, 05:27 AM

Quote:

Originally Posted by michaelk

Check permissions of keys. Use -v option with ssh commands to help debug.

Did you change anything?

after creating the config file on ~/.ssh , I removed "AddKeysToAgent ask"

then i made sure to forward port 22 on localhost, on section 'gaming&applicaitons' of my modem (confirmed with https://www.yougetsignal.com/tools/open-ports/)

p.s.: permission for keys is set to darkstar users

Turbocapitalist · 02-06-2019, 05:28 AM

What about the file name for the key?

however · 02-06-2019, 05:32 AM

Quote:

Originally Posted by Turbocapitalist

What about the file name for the key?

/.ssh/id_rsa and id_rsa.pub

beside any issues with the keys, should i not be able to connect to localhost though?

Code:

bash-4.2$ ssh -v localhost
OpenSSH_6.3, OpenSSL 1.0.1e 11 Feb 2013
debug1: Reading configuration data /home/darkstar/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: Connection established.
debug1: identity file /home/darkstar/.ssh/id_rsa type 1
debug1: identity file /home/darkstar/.ssh/id_rsa-cert type -1
debug1: identity file /home/darkstar/.ssh/id_dsa type -1
debug1: identity file /home/darkstar/.ssh/id_dsa-cert type -1
debug1: identity file /home/darkstar/.ssh/id_ecdsa type -1
debug1: identity file /home/darkstar/.ssh/id_ecdsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.3
debug1: match: OpenSSH_6.3 pat OpenSSH*
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com none
debug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 8b:ae:92:a9:ec:8e:d9:ce:4d:20:e0:cf:6f:b6:78:f7
debug1: Host 'localhost' is known and matches the ECDSA host key.
debug1: Found key in /home/darkstar/.ssh/known_hosts:3
debug1: ssh_ecdsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/darkstar/.ssh/id_rsa
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Trying private key: /home/darkstar/.ssh/id_dsa
debug1: Trying private key: /home/darkstar/.ssh/id_ecdsa
debug1: Next authentication method: keyboard-interactive
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: No more authentication methods to try.
Permission denied (publickey,keyboard-interactive).
bash-4.2$

michaelk · 02-06-2019, 05:40 AM

Does your home desktop have an authorized_keys file?