How to ssh to localhost without password? - networking

Question

EDIT: Putting exactly what was done
I need to SSH localhost without password, the usual way of doing it (with public keys) do not work.
user#PC:~$ rm -rf .ssh/*
user#PC:~$ ssh-keygen -t rsa > /dev/null
Enter file in which to save the key (/home/user/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
user#PC:~$ ls .ssh/
id_rsa id_rsa.pub
user#PC:~$ ssh-copy-id -i localhost
The authenticity of host 'localhost (::1)' can't be established.
RSA key fingerprint is f7:87:b5:4e:31:a1:72:11:8e:5f:d2:61:bd:b3:40:1a.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
user#localhost's password:
Now try logging into the machine, with "ssh 'localhost'", and check in:
.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.
user#PC:~$ ssh-agent $SHELL
user#PC:~$ ssh-add -L
The agent has no identities.
user#PC:~$ ssh-add
Identity added: /home/user/.ssh/id_rsa (/home/user/.ssh/id_rsa)
user#PC:~$ ssh-add -L
ssh-rsa ...MY KEY HERE
user#PC:~$ ssh-copy-id -i localhost
user#localhost's password:
Now try logging into the machine, with "ssh 'localhost'", and check in:
.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.
user#PC:~$ ssh localhost echo 'testing'
user#localhost's password:
user#PC:~$
So as you can see in the last command it is still asking the password!
How can I fix that? Ubuntu-10.04, OpenSSH_5.3p1
EDIT2:
Adding some info about the sshd
user#PC:~$ cat /etc/ssh/sshd_config | grep Authentication
# Authentication:
RSAAuthentication yes
PubkeyAuthentication yes
RhostsRSAAuthentication no
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
ChallengeResponseAuthentication no
# PasswordAuthentication yes
EDIT3: Ading result from $ssh -vv localhost
$ssh -vv localhost
...
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /home/user/.ssh/identity
debug1: Offering public key: /home/user/.ssh/id_rsa
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/user/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug1: Next authentication method: password
user#localhost's password:

Answer 1

I did following 3 steps to create the password less login
1. ssh-keygen -t rsa
Press enter for each line
2. cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
3. chmod og-wx ~/.ssh/authorized_keys

Answer 2

Have discovered the problem.
Running the server with debuging:
$sshd -Dd
I found it was not able to read the auth_key
$chmod 750 $HOME
Fixed it.

Answer 3

Another possible answer: the authorized_keys file may exist and be readable. But if it is group- or world-writable, it will still prompt for the password. The answer to THAT problem is
chmod og-wx ~/.ssh/authorized_keys

Answer 4

Two simple steps:
ssh-keygen -t rsa <Press enter for each line>
ssh-copy-id localhost
Enter password and you're done.

Answer 5

Do the following steps
ssh-keygen -t rsa -C "your_email#example.com"
# Creates a new ssh key, using the provided email as a label
# Generating public/private rsa key pair.
Use the default file and empty passphrase (Simply press enter in the next 2 steps)
# start the ssh-agent in the background
eval "$(ssh-agent -s)"
# Agent pid 59566
ssh-add
Copy the contents of ~/.ssh/id_rsa.pub to ~/.ssh/authorized_keys
Ensure following are the permissions
ls -l .ssh/
total 20
-rw-r--r--. 1 swati swati 399 May 5 14:53 authorized_keys
-rw-r--r--. 1 swati swati 761 Jan 12 15:59 config
-rw-------. 1 swati swati 1671 Jan 12 15:44 id_rsa
-rw-r--r--. 1 swati swati 399 Jan 12 15:44 id_rsa.pub
-rw-r--r--. 1 swati swati 410 Jan 12 15:46 known_hosts
Also, ensure the permissions for .ssh directory are. This is also important
drwx------. 2 swati swati 4096 May 5 14:56 .ssh

Answer 6

The correct and safe way of doing it is to copy the keys as has been said here.
In other cases, sshpass can be handy.
sshpass -p raspberry ssh pi#192.168.0.145
Keep in mind that this is not safe at all. Even though it is not a good idea to use it in secure environments, it can be useful for scripting, automated testing...
this can be combined with
ssh -q -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no pi#192.168.0.145
to avoid confirmation questions that prevent scripting from happening.
Again, only use this in development systems where different machines share an IP and security is not important.
https://ownyourbits.com/2017/02/22/easy-passwordless-ssh-with-sshh/

Answer 7

as the accepted answer do,
if you encount a problem of
Agent admitted failure to sign using the key.
you need to
ssh-add

Answer 8

I faced the same issue even after following all the recommendations, but found out that the issue was with gnome-keyring interference.
Solution:
Go Search , look for “Startup Applications”
If you see “SSH Key Agent”, uncheck the box
Reboot the machine and connect to localhost.

Answer 9

I solved ssh login problem this way.
I generate the key pairs on my server side and then scp back the private key to my windows 10 computer and now I can login without password.
Previously I used key pairs generated by my window 10 laptop and there was no luck at all.

Answer 10

On Centos 7
SOLUTION
1 create rsa key
2 vim /etc/ssh/ssh_config
3
# IdentityFile ~/.ssh/identity
uncoment this line > IdentityFile ~/.ssh/id_rsa
# IdentityFile ~/.ssh/id_dsa
# IdentityFile ~/.ssh/id_ecdsa
Note *I did this after copying the key and some of the other answers before this one. But I am pretty sure this is all you have to do but if not I would append the rsa key to authorized_keys and also run the
ssh-copy-id to username#localhost

Answer 11

I encountered the same problem when running unit tests on Docker container(golang:1.13-alpine).
After sshd -Dd and ssh -vv root#localhost debugging, I found the reason:
User root not allowed because account is locked
So, we should unlock the account by passwd -u
or set a password.

Answer 12

I fixed my problem setting the AllowUsers on sshd_config file.
Running the server with debuging:
$sshd -Dd
I found it was not allowed the my user
$sudo vi /etc/ssh/sshd_config
Add a row with after #Authentication:
AllowUsers myUser

Answer 13

One thing to doublecheck if you have a known good configuration for ssh is that your /etc/hosts.allow includes a reference to localhost, since the source IP for a localhost connection would be coming from 127.0.0.1 rather than your network IP. I was stumped on this for some time, but after adding the following to /etc/hosts.allow my configuration immediately worked.
ALL: 127.0.0.1/32
I figured I would add this since none of the other answers mentioned it and this was the top hit from my search for the same error.

Answer 14

RHEL8
In my case after successful keys configuration it still did not work. I found following error in /var/log/secure:
pam_access(sshd:account): access denied for user `username' from `::1'
So I had to edit:
/etc/security/access.conf
And add there '::1' to allowed hosts by adding a line:
+:<username>:LOCAL ::1
It immediately started to work, even without restart of sshd service.