I've been trying "ssh localhost" on cygwin (I use WIndows 7), but it keeps asking for the password.
When I did "ssh -vvv localhost", I found out that the public key authentications were not happening (or failing). Hence, it was asking for the password.
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: Offering RSA public key: /home/xxxxxxxx/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password,keyboard-interactive
I'm not sure if it is unable to read the authorized_keys file, or if there is a timeout issue with this, or did the authentication fail? Is there any way to get more details?
I have done the following steps:
ssh-host-config. Answered yes to all.
Generated the RSA key and added it to the authorized_keys file.
net start sshd
ssh localhost
These are the permissions:
-rw------- 1 xxxxxxxx mkgroup 402 May 18 16:34 authorized_keys
-rw------- 1 xxxxxxxx mkgroup 1675 May 18 16:33 id_rsa
-rw-r--r-- 1 xxxxxxxx mkgroup 402 May 18 16:33 id_rsa.pub
-rw-r--r-- 1 xxxxxxxx mkgroup 171 May 18 14:33 known_hosts
There are a couple of issues as well:
- The group is displayed as mkgroup.
- The user "xxxxxxxx" does not exist in the localhost, I guess.
It was not displayed in "net user sshd". "xxxxxxxx" is a Domain account.
Could this be causing the public key authentication issue?
Just to see if there is any difference in the output, I deleted the authorized_keys file and tried. There was no difference in the output. It still sends a packet and proceeds to the next mode of authentication. There is no error message. Is there any other way to get more details (I'm a Cygwin and SSH n00b)? I would like to find it fails while reading the authorized_keys file.
Quick double-check, did you add your public key or private key to authorized_keys? It needs to be your public key.
I notice that the server is not responding with a "Server accepts key..." upon receipt of your pubkey_test and I have seen that when the public key is missing from the authorized_keys file on the server you're connecting to. You should see:
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 279
Easiest way to set it up is to use ssh-copy-id to do the work, e.g.,:
# ssh-copy-id localhost
That will create your authorized_keys file with the correct permissions. When you run this, you will be prompted for your password, because the server doesn't have the key. Once this command runs successfully, you'll be able to simply ssh to the server using your identity file. Note that ssh_config defaults the identity file to ~/.ssh/identity, ~/.ssh/id_rsa, ~/.ssh/id_dsa, so if you want to use a different file, you should set up an alias in ~/.ssh/config.
Hope this helps.
My problem was that I thought cygwin is OK if its files gets copy and pasted, so if I wanted to clone the installation I just copied and pasted C:\cygiwn64 folder somewhere else and ran the .bat file.
But I was wrong. Every time you copy a file with windows explorer the permission and ownerships gets corrupted in cygwin. So dont use windows explorer for making changes to any of the cygwin files, only use the command line apps like cp, mkdir, mv, vim, nano and others.
Also If you want to create a new installation just use the setup_x86_64.exe file and simply choose a new root directory for it and let the setup install packages and do the rest for you.
This way you make sure that nothing gets corrupted and you wont get surprised by some amazing error messages in the future.
At the very least you need to
chmod 700 id_rsa
This is
my setup
if it helps
-rwx------ 1 Steven None 1675 May 17 12:49 id_rsa
-rwx------ 1 Steven None 399 May 17 12:49 id_rsa.pub
-rwx------ 1 Steven None 803 May 18 01:13 known_hosts
It appears that there are some problems with your cygwin setup, which is why the user/group is not showing up correctly. You need to run mkgroup to generate your /etc/group, and possibly mkpasswd as well. I had a similar problem - I had to run mkpasswd to regenerate my /etc/passwd. After running mkpasswd, I could finally ssh into my localhost. It's a shame the debug info does not log enough info to easily diagnose the problem.
This page describes more about Windows security in cygwin: http://cygwin.com/cygwin-ug-net/ntsec.html#ntsec-setuid-overview
I had a similar problem setting up public key authentication (with similar verbose output from the client), though I was trying to do it from an Ubuntu client to a Cygwin SSHD server, and it was a very old Cygwin environment (version 1.5.12 on Windows 2000!). I had copied the public key using ssh-copy-id.
In my case, making the authorized_keys files world readable (mode 644) on the Cygwin side appeared to allow public key authentication to succeed.
From what I've seen, mode 600 is standard, so perhaps this "fix" in my case is actually a sign of a problem elsewhere in the Cygwin SSHD setup. But now that pub key authentication is finally working, I probably won't be digging any deeper.
Re-Install it on
C:\
Many problems will be solved.
Related
I want to estabilsh a ssh Connection in Windows 10 but following Error occured :
debug2: input_userauth_info_req: num_prompts 1 debug3: failed to open file:C:/dev/tty error:3 debug1: read_passphrase: can't open /dev/tty: No such file or directory
This thread suggests such an error message is the manifestation/side-effect of an error not seen in your message.
the fundamental issue was a misunderstanding of your ssh instructions online.
I thought authorized_keys was a folder to contain the file id_rsa.pub rather than a file to contain the key itself.
This stemmed from my limited understanding of ssh conventions.
So double-check you did register the right key (public one) to the remote account $HOME/.ssh/authorized_keys file.
I had the same problem and found your question after searching for the "read_passphrase" error, so if anyone follows... I eventually found this little gem that explains how git for Windows uses its own SSH binaries by default, and doesn't integrate with e.g. Windows SSH Agent.
Setting up Windows SSH agent and adding the GIT_SSH environment as directed fixed my tty issues, and I don't have to enter my passphrase every time.
https://snowdrift.tech/cli/ssh/git/tutorials/2019/01/31/using-ssh-agent-git-windows.html#linking-to-git
I have tried to setup public key connection between AIX to AIX and that's working and I am facing problem while I setup same public key connection between AIX and DataPower appliance.
I could see in logs that's connection established but while using public I am not able to login and everytime expecting to enter password manually.
Can someone please help on this?
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
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: Offering RSA public key: ./***_rsa.pub
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
There are many, many reasons why client-side debugging (ssh -vvv ...) shows:
debug2: we did not send a packet, disable method
Many of these are listed in the answers to SSH public key won't send to server on Unix & Linux, but, unfortunately, the client does not give any indication as to which one applies.
When I was struggling with this, my main problem was getting server-side logging/debugging to show. Of great help was the following (paraphrased) suggestion taken from Ciro Santilli 冠状病毒审查六四事件法轮功's answer to How to check sshd log? on ServerFault:
Start a new SSH Server instance on a new port in debug mode with:
/usr/sbin/sshd -d -p 2222
then connect to it from the client with:
ssh -p 2222 user#host
If you have sudo access to the destination server, check the SSH logs (/var/log/secure), it may give you some clue. For my case it was a bad permission on the home directory.
chmod g-w /home/user
chmod 700 /home/user/.ssh
chmod 600 /home/user/.ssh/authorized_keys
Reference: https://chemicloud.com/kb/article/ssh-authentication-refused-bad-ownership-or-modes-for-directory/
I solved the same problem
(when I checked in my system there is .ssh/authorized_keys : the filename was wrong)
this way:
cp -p .ssh/authorised_keys .ssh/authorized_keys
Check the ssh configuration on remote server to find if remote system is accepting type of key being passed.
Check the file /etc/ssh/sshd_config and look for property PubkeyAcceptedKeyTypes to confirm that it accepts key type being passed. For instance, here the key type seems to be ssh-rsa, so that should be added to the list of PubkeyAcceptedKeyTypes
(or for maximium compatibility PubkeyAcceptedKeyTypes *)
Once added, restart sshd daemon
EX:
sudo sed -i "/.*PubkeyAcceptedKeyTypes.*/d" /etc/ssh/sshd_config
sudo sed -i "/.*RSAAuthentication.*/d" /etc/ssh/sshd_config
sudo sed -i "/.*PubkeyAuthentication.*/d" /etc/ssh/sshd_config
sudo sed -i "/.*PasswordAuthentication.*/d" /etc/ssh/sshd_config
sudo sed -i "/.*PermitRootLogin.*/d" /etc/ssh/sshd_config
echo "PubkeyAcceptedKeyTypes *" | sudo tee -a /etc/ssh/sshd_config
echo "RSAAuthentication yes" | sudo tee -a /etc/ssh/sshd_config
echo "PubkeyAuthentication yes" | sudo tee -a /etc/ssh/sshd_config
echo "PasswordAuthentication no" | sudo tee -a /etc/ssh/sshd_config
echo "PermitRootLogin no" | sudo tee -a /etc/ssh/sshd_config
sudo systemctl restart sshd.service
sudo systemctl status sshd.service | grep -i success
Refer to this answer SSH public key won't send to server.
In your log
Offering RSA public key: ./***_rsa.pub
...
we did not send a packet, disable method
It means that the client didn't send the key file. So make sure the key file exists.
Check the key file is in your local path
Make sure the public key content is copied into ~/.ssh/authorized_keys in remote server.
I've just had the same problem. Two raspberry Pis on my local network - one connected, one didn't (with the 'debug2: we did not send a packet, disable method' error)
after 4 hours I found the problem
Being used to uk spelling I created the 'authorised_users' file not 'authorized_users'
Doh !!
So what happened for me is that I have 2 VMs to access from my local machine (2 keys id_rsa.pub and id_rsa2.pub). I realized that my ssh connection is using id_rsa.pub by default for any ssh user#xx.xx.xx.xx connection. I solved my issue by adding a config file and specify the identity to be used for every host like the following :
vi ~/.ssh/config
Add both hostnames and their identity file as follows:
Host server1.nixcraft.com
IdentityFile ~/Users/.ssh/id_rsa1
Host server2.nixcraft.com
IdentityFile ~/Users/.ssh/id_rsa2
This happened to me and, after several hours banging my head against the wall, I realized there was a typo in the public key file. Instead of beginning with
ssh-rsa
there was a + sign at the beginning:
+ssh-rsa
I know it's obvious in retrospect, but it doesn't hurt to double check your file.
It looks like there can be a lot of things causing this problem. In my case I forgot to specified the User name in my ~/.ssh/config file. Apparently, it depends on your current login name.
Host dev
HostName 1.2.3.4
IdentityFile ~/.ssh/id_rsa
User John
This can happen if in your /etc/ssh/sshd_config you have the following entry
PubkeyAcceptedKeyTypes=+ssh-dss
as opposed to
PubkeyAcceptedKeyTypes +ssh-dss #this is the correct entry
After updating this, be sure to issue a
sudo systemctl restart sshd #Ubuntu
Think about selinux, if is enabled,do:
# sudo ausearch -c "sshd" --raw | audit2allow -M my-sshd
# sudo semodule -i my-sshd.pp
I checked and tried every instruction given here and after several hours of troubleshooting, I noticed the SSH server (which is my router) does not have a support for ed25519. Dropbear was spamming the following log: Pubkey auth attempt with unknown algo...
Using an RSA type fixed my issue.
Just for those who have the log "we did not send a packet, disable method" when trying to use a public key.
Check your sshd_config file on the remote server and force "PubkeyAuthentication" to "yes", even if it should be "yes" by default.
For me it solved my connection problem.
In my case the private key must have been added to the agent with:
ssh-add ~/.ssh/private_id_rsa
I am trying to ssh login to my remote server. But whenever i try to login through terminal using ssh command:
ssh root#{ip_address}
I get error:
Connection closed by {ip_address}
I checked hosts deny and hosts allow, there is nothing in the file. I am not getting why it happening?
It happened when i changed my workstation and key got changed. When i tried ssh login, it asked to add key and i entered yes and then it closed the connection.
Is there any way to get connected with ssh again?
Your help is appreciated.
Thank you.
Edit:
Output of ssh -v -v -v -v root#{ip_address} is
OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to {ip_address} [{ip_address}] port 22.
debug1: Connection established.
debug3: Incorrect RSA1 identifier
debug3: Could not load "/home/mona/.ssh/id_rsa" as a RSA1 public key
debug1: identity file /home/mona/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/mona/.ssh/id_rsa-cert type -1
debug1: identity file /home/mona/.ssh/id_dsa type -1
debug1: identity file /home/mona/.ssh/id_dsa-cert type -1
debug1: identity file /home/mona/.ssh/id_ecdsa type -1
debug1: identity file /home/mona/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1.1
debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1.1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1
debug2: fd 3 setting O_NONBLOCK
debug3: load_hostkeys: loading entries for host "{ip_address}" from file "/home/mona/.ssh/known_hosts"
debug3: load_hostkeys: loaded 0 keys
debug1: SSH2_MSG_KEXINIT sent
Connection closed by 151.236.220.15
Had the same issue but a simple remote server reboot helped.
Are you sure your server is permitting root logins via SSH?
If not, I suggest using a different account with sudo privileges instead of enabling root login - especially if the server's SSH port is accessible from the whole inernet.
try sudo ssh root#{ip_address}, it works for me.
I tried to connect with a user, which had :/bin/false in /etc/passwd. After changing it to :/bin/bash the connection was not closed anymore.
I had a similar issue that was resolved by lowering the MTU on the client side with the following command:
ip li set mtu 1400 dev eth0
I found this solution from a separate thread on serverfault.
I was getting the same "Connection closed by {ip_address}" error on one of my SSH connections. I tried all the usual solutions and nothing worked. Finally I found that the ~/.ssh/authorized_keys file on the host was corrupted. Someone had tried to append a key to the file, but they copied and pasted it with embedded line feeds where each line wrapped at the end. So what should have been one continuous string spanning three lines was actually three separate strings -- one per line. Since the embedded line feed was exactly at the end of the line, it was not apparent from looking at it.
I deleted the offending key and added my own. Then everything worked as expected.
I temporarily disabled my antivirus firewall and this maybe helped a bit.
Now it suddenly says Shell access is not enabled on yr account! Connection closed.
So I logged into my WHM server.domain_name:2087 and clicked on Modify domain and enabled Shell Access for the website.
(Or ask your host provider to enable SSh for you if you do not have a WHM server)
Login success, it now says:
Last login: 03:37 from . [user#whm_domain_name ~]$
I myself had same problems while working with cloud9 editor. Mine was cause from high CPU usage. It would get fine after stopping apache connection.
Check the name being used to connect to the ftp site, its either wrong or multiple names are being sent for uthentication.
This is what I tried to do ten times today without success:
make a key with ssh-keygen.
open ~/.ssh/id_rsa.pub with Gedit or Notepad++ and copy the contents.
Go to account settings on github.com
Go to SSH Keys
Click on the Add Key button.
give the key a title
paste the key into the key box.
Save the key (enter my github password to verify).
Then, I run '$ ssh -vT git#github.com' in cygwin, but it always hang on there. Here is the output:
$ ssh -vT git#github.com
OpenSSH_6.0p1, OpenSSL 1.0.1c 10 May 2012
debug1: Reading configuration data /home/eason.wu/.ssh/config
debug1: /home/eason.wu/.ssh/config line 1: Applying options for github.com
debug1: Reading configuration data /etc/ssh_config
debug1: Connecting to github.com [207.97.227.239] port 22.
debug1: Connection established.
debug1: identity file /home/eason.wu/.ssh/id_rsa type 1
debug1: identity file /home/eason.wu/.ssh/id_rsa-cert type -1
Does any one meet this problem, any solution will be appreciated
Make sure you did copy the public key as one line, because a copy from an editor can sometime buffer the content of that key as several lines.
If you still have an issue, check other SSH debug tips at "Unable to Git-push master to Github".
A ssh -vvvT git#github.com can display more debug information.
The OP Eason Wu comments:
I found the real reason of this problem, it is caused by my network.
Some websites are prohibited by my company, I would think it also affects GitHub service.
After I turn on an VPN connection, and retest again with ssh -vvvT git#github.com, it passed successfully
For anyone coming here recently looking for a solution, this was happening to me too, however in the debug (as per above instruction) the connection to GitHub never established.
My output looked like:
OpenSSH_7.9p1 Ubuntu-10, OpenSSL 1.1.1b 26 Feb 2019
debug1: Reading configuration data /home/preston/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "github.com" port 22
debug2: ssh_connect_direct
debug1: Connecting to github.com [2607:7700:0:1a:0:1:c01e:ff70] port 22.
I noticed the IPv6 address in the last line and thought that might be the issue. So I sourced an article on changing it to use an IPv4 address in the global ssh settings.
Changing to IPv4 worked.
Source: https://stackoverflow.com/a/35113901/3818056
For me, the issue was the router I was connected to was using WPA, not WPA2/3. Once I changed to a network that didn't have this issue my repo was instantly cloned with ssh.
I solved this by adding GitHub "github.com" in the whitelist of my router. You can also overcome this by VPN however it will require another set of steps to find a VPN and setup.
I added the public SSH key to the authorized_keys file. ssh localhost should log me in without asking for the password.
I did that and tried typing ssh localhost, but it still asks me to type in the password. Is there another setting that I have to go through to make it work?
I have followed the instructions for changing permissions:
Below is the result if I do ssh -v localhost.
debug1: Reading configuration data /home/john/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: Connection established.
debug1: identity file /home/john/.ssh/identity type 1
debug1: identity file /home/john/.ssh/id_rsa type -1
debug1: identity file /home/john/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.7p1 Debian-8ubuntu3
debug1: match: OpenSSH_4.7p1 Debian-8ubuntu3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.7p1 Debian-8ubuntu3
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'localhost' is known and matches the RSA host key.
debug1: Found key in /home/john/.ssh/known_hosts:12
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering public key: /home/john/.ssh/identity
debug1: Server accepts key: pkalg ssh-rsa blen 149
debug1: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
Then it asks for a passphase after the above log. Why isn't it logging me in without a password?
You need to verify the permissions of the authorized_keys file and the folder / parent folders in which it is located.
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
For more information see this page.
You may also need to change/verify the permissions of your home directory to remove write access for the group and others.
chmod go-w ~
SELinux can also cause authorized_keys not to work. Especially for root in CentOS 6 and 7. There isn't any need to disable it though.
Once you've verified your permissions are correct, you can fix this like so:
chmod 700 /root/.ssh
chmod 600 /root/.ssh/authorized_keys
restorecon -R -v /root/.ssh
Setting ssh authorized_keys seem to be simple, but it hides some traps I'm trying to figure.
-- SERVER --
In /etc/ssh/sshd_config, set passwordAuthentication yes to let the server temporarily accept password authentication
-- CLIENT --
consider Cygwin as Linux emulation and install & run OpenSSH
1. Generate private and public keys (client side)
# ssh-keygen
Here pressing just Enter, you get default two files, "id_rsa" and "id_rsa.pub", in ~/.ssh/, but if you give a name_for_the_key, the generated files are saved in your current working directory.
2. Transfer the your_key.pub file to the target machine, ssh-copy-id user_name#host_name
If you didn't create a default key, this is the first step to go wrong
... you should use:
ssh-copy-id -i path/to/key_name.pub user_name#host_name
3. Logging ssh user_name#host_name will work only for the default id_rsa file, so here is the second trap. You need to do ssh -i path/to/key_name user#host
(Use ssh -v ... option to see what is happening.)
If the server still asks for a password then you gave something. To Enter passphrase: when you've created keys (so it's normal).
If ssh is not listening on the default port 22, you must use ssh -p port_nr.
-- SERVER -----
4. Modify file /etc/ssh/sshd_config to have
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile %h/.ssh/authorized_keys
(uncomment if case)
This tells ssh to accept file authorized_keys and look in the user home directory for the key_name sting written in the .ssh/authorized_keys file.
5 Set permissions on the target machine
chmod 755 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
Also turn off pass authentication,
passwordAuthentication no
to close the gate to all ssh root/admin/....#your_domain attempts.
6. Ensure ownership and group ownership of all non-root home directories are appropriate.
chown -R ~ usernamehere
chgrp -R ~/.ssh/ user
===============================================
7. Consider the excellent http://www.fail2ban.org
8. Extra
SSH tunnel to access a MySQL (bind = 127.0.0.1) server
Also be sure your home directory is not writeable by others:
chmod g-w,o-w /home/USERNAME
This answer is stolen from here.
The desperate may also make sure they don't have extra newlines in the authorized_keys file due to copying file id_rsa.pub's text out of a confused terminal.
Listing a public key in .ssh/authorized_keys is necessary, but not sufficient for sshd (server) to accept it. If your private key is passphrase-protected, you'll need to give ssh (client) the passphrase every time. Or you can use ssh-agent, or a GNOME equivalent.
Your updated trace is consistent with a passphrase-protected private key. See ssh-agent, or use ssh-keygen -p.
In the following, user is your username.
mkdir -p /home/user/.ssh
ssh-keygen -t rsa
touch /home/user/.ssh/authorized_keys
touch /home/user/.ssh/known_hosts
chown -R user:user /home/user/.ssh
chmod 700 /home/user/.ssh
chmod 600 /home/user/.ssh/id*
chmod 644 /home/user/.ssh/id*.pub
chmod 644 /home/user/.ssh/authorized_keys
chmod 644 /home/user/.ssh/known_hosts
Beware that SELinux can trigger this error as well, even if all permissions seem to be OK. Disabling it did the trick for me (insert usual disclaimers about disabling it).
Look in file /var/log/auth.log on the server for sshd authentication errors.
If all else fails, then run the sshd server in debug mode:
sudo /usr/sbin/sshd -ddd -p 2200
Then connect from the client:
ssh user#host -p 2200
In my case, I found the error section at the end:
debug1: userauth_pubkey: test whether pkalg/pkblob are acceptable for RSA SHA256:6bL+waAtghY5BOaY9i+pIX9wHJHvY4r/mOh2YaL9RvQ [preauth]
==> debug2: userauth_pubkey: disabled because of invalid user [preauth]
debug2: userauth_pubkey: authenticated 0 pkalg ssh-rsa [preauth]
debug3: userauth_finish: failure partial=0 next methods="publickey,password" [preauth]
debug3: send packet: type 51 [preauth]
debug3: receive packet: type 50 [preauth]
With this information I realized that my sshd_config file was restricting logins to members of the ssh group. The following command fixed this permission error:
sudo usermod -a -G ssh NEW_USER
Try "ssh-add" which worked for me.
The thing that did the trick for me finally was to make sure that the owner/group were not root, but user:
chown -R ~/.ssh/ user
chgrp -R ~/.ssh/ user
Issue these on the command line:
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
After you do this, make sure your directory is like this:
drwx------ 2 lab lab 4.0K Mar 13 08:33 .
drwx------ 8 lab lab 4.0K Mar 13 08:07 ..
-rw------- 1 lab lab 436 Mar 13 08:33 authorized_keys
-rw------- 1 lab lab 1.7K Mar 13 07:35 id_rsa
-rw-r--r-- 1 lab lab 413 Mar 13 07:35 id_rsa.pub
In my case I needed to put my authorized_keys file in .openssh.
This location is specified in /etc/ssh/sshd_config under the option AuthorizedKeysFile %h/.ssh/authorized_keys.
Another tip to remember: Since v7.0 OpenSSH disables DSS/DSA SSH keys by default due to their inherit weakness. So if you have OpenSSH v7.0+, make sure your key is not ssh-dss.
If you are stuck with DSA keys, you can re-enable support locally by
updating your sshd_config and ~/.ssh/config files with lines like so: PubkeyAcceptedKeyTypes=+ssh-dss
Another issue you have to take care of: If your generated file names are not the default id_rsa and id_rsa.pub.
You have to create the .ssh/config file and define manually which id file you are going to use with the connection.
An example is here:
Host remote_host_name
HostName 172.xx.xx.xx
User my_user
IdentityFile /home/my_user/.ssh/my_user_custom
Make sure that the target user has a password set. Run passwd username to set one. This was required for me even if password SSH login was disabled.
Just look in file /var/log/auth.log on the server. Setting additional verbosity with -vv on the client side won't help, because the server is unlikely to offer too much information to a possible attacker.
My problem was a modified AuthorizedKeysFile, when the automation to populate /etc/ssh/authorized_keys had not yet been run.
$sudo grep AuthorizedKeysFile /etc/ssh/sshd_config
#AuthorizedKeysFile .ssh/authorized_keys
AuthorizedKeysFile /etc/ssh/authorized_keys/%u
Make sure you've copied the whole public key to authorized_keys; the ssh rsa prefix is necessary for the key to work.
I issued sudo chmod 700 ~/.ssh and chmod 600 ~/.ssh/authorized_keys and chmod go-w $HOME $HOME/.ssh from a previous answer and it fixed my problem on a CentOS 7 box that I had messed up the permissions on while trying to get Samba shares working.
It seems like a permission problem. Usually it happens if the permission of some file/directory is not correctly set up. In most case they are ~/.ssh and ~/.ssh/*. In my case they are /home/xxx.
You can change the log level of sshd by modifying file /etc/ssh/sshd_config(search for LogLevel, and set it to DEBUG) and then check the output in file /var/log/auth.log to see what happened exactly.
This solves my problem:
ssh-agent bash
ssh-add
In my case it's because the user's group is not set in AllowGroups of configuration file /etc/ssh/sshd_config. After adding it, everything works fine.
You need to verify the properties of the files.
To assign the required property, use:
$ chmod 600 ~/.ssh/sshKey
$ chmod 644 ~/.ssh/sshKey.pub
I use it this way.
cat ~/.ssh/id_rsa.pub| ssh user#remote-system 'umask 077; cat >>~/.ssh/authorized_keys'
On that note, make sure your sshd configuration has this line:
PermitRootLogin without-password
Set as the above, and then restart sshd (/etc/init.d/sshd restart).
Log out and try log in in again!
The default, I believe, is:
PermitRootLogin no
I have the home directory in a non-standard location and in sshd logs I have the following line, even if all permissions were just fine (see the other answers):
Could not open authorized keys '/data/home/user1/.ssh/authorized_keys': Permission denied
I have found a solution here: Trouble with ssh public key authentication to RHEL 6.5
In my particular case:
Added a new line in /etc/selinux/targeted/contexts/files/file_contexts.homedirs:
This is the original line for regular home directories:
/home/[^/]*/\.ssh(/.*)? unconfined_u:object_r:ssh_home_t:s0
This is my new line:
/data/home/[^/]*/\.ssh(/.*)? unconfined_u:object_r:ssh_home_t:s0
Followed by a restorecon -r /data/ and a sshd restart.
I had this problem and none of the other answers solved it, although of course the other answers were correct.
In my case, it turned out that the /root directory itself (not e.g. /root/.ssh) had the wrong permissions. I needed:
chown root.root /root
chmod 700 /root
Of course, those permissions should be something like that (maybe chmod 770) regardless. However, it specifically prevented sshd from working, even though /root/.ssh and /root/.ssh/authorized_keys both had correct permissions and owners.
I had this problem when I added the group of the login user to another user.
Let's say there is an SSH-login user called userA and a non-SSH-login user userB. userA has the group userA as well. I modified userB to have the group userA as well. The lead to the the described behaviour, so that userA was not able to login without a prompt.
After I removed the group userA from userB, the login without a prompt worked again.
I have had the same issues since before, but today I had to set up one new server. What I could learn in this time...
The basic process to allow authentication without a password is as follows:
On the server, validate if your home folder has the .ssh folder. If it doesn't exist, you can create it manually with a mkdir command and then to assign the correct permissions with chmod, or otherwise you could use the same utility, ssh-keygen, to create private/public keys, but on the server for your user. This process will create the required .ssh folder.
On the local machine you also need to create the private/public keys with the ssh-keygen utility.
You need to move your public key to file .ssh/authorized_keys to the server. To achieve this, you can use the ssh-copy-id utility, or you can do it manually using the cat and scp commands.
In the best of cases, this will allow connect to your server without a password.
OK, now the issues that I found today: first there are several key generation algorithms: rsa, dsa, ecdsa and ed25519 and there are many releases of OpenSSH (you can have one version on your local machine and an old version on your server):
Hint: Using ssh -v helps to see additional information when you are connecting to the server.
OpenSSH_8.2p1 Ubuntu-4, OpenSSL 1.1.1f 31 Mar 2020
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
The error in my case today was that I was trying to use a key with a "newer" generation algorithm that was not supported by the installed version of OpenSSH on the server. When I had checked the supported algorithms, another error that I found was that the server was rejecting my algorithm:
debug1: Skipping ssh-dss key /home/user/.ssh/id_dsa - not in PubkeyAcceptedKeyTypes
After that, I had to change the algorithm of my key and then I could connect with the server successfully.
OpenSSH releases notes: Link