SSH connection refused When I’m playing with my Raspberry Pi, I install a new version of the system, and then ssh does not work. I’m constantly googling around this, and here are my steps to check it. Look at the error:
ssh jonatas@rpi
ssh: connect to host rpi port 22: Connection refused
Let’s see what we can do to overcome it.
Configuring /etc/hosts for fun
It’s a bit out of topic, but I love to share how I organize my development environment, and the first tip is: use /etc/hosts to map IPs that you use often.
Here is my rpi name pointing to my Raspberry Pi IP in the local network:
grep rpi /etc/hosts
192.168.53.156 rpi
At my Raspberry Pi, I already have used sudo apt install openssh-server, but when I try to connect, this is what I get:
Checking the network with simple ping:
ping rpi
PING rpi (192.168.53.156): 56 data bytes
64 bytes from 192.168.53.156: icmp_seq=0 ttl=64 time=19.967 ms
64 bytes from 192.168.53.156: icmp_seq=1 ttl=64 time=18.345 ms
Checking what is the SSH Port configured in your Raspberry
On the Raspberry Pi, the first step is to check the ssh configuration port.
It’s a file /etc/ssh/ssh_config, and we’re going to use the grep command again to search for Port:
grep Port /etc/ssh/ssh_config
# Port 22
If the port is commented like in my case, starting with #, that means it’s
using the default port. If you have like Port 221, probably you should
consider adding -p 221 to your ssh command.
Checking SSH service status
Now, let’s understand the why. sudo service <name> status can help to understand what’s going on:
sudo service ssh status
Checking the output:
Process: 2916 ExecStart=/usr/sbin/sshd -D $SSHD_OPTS (code=exited, status=0/SUCCESS)
Process: 2915 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Main PID: 2916 (code=exited, status=0/SUCCESS)
mai 21 15:35:33 rpi-3 sshd[2922]: error: Could not load host key: /etc/ssh/ssh_host_ecdsa_key
mai 21 15:35:33 rpi-3 sshd[2922]: error: Could not load host key: /etc/ssh/ssh_host_ed25519_key
mai 21 15:35:33 rpi-3 sshd[2922]: fatal: No supported key exchange algorithms [preauth]
mai 21 15:36:09 rpi-3 sshd[2925]: error: Could not load host key: /etc/ssh/ssh_host_rsa_key
mai 21 15:36:09 rpi-3 sshd[2925]: error: Could not load host key: /etc/ssh/ssh_host_ecdsa_key
mai 21 15:36:09 rpi-3 sshd[2925]: error: Could not load host key: /etc/ssh/ssh_host_ed25519_key
mai 21 15:36:09 rpi-3 sshd[2925]: fatal: No supported key exchange algorithms [preauth]
mai 21 15:36:31 rpi-3 systemd[1]: Stopping OpenBSD Secure Shell server...
mai 21 15:36:31 rpi-3 sshd[2916]: Received signal 15; terminating.
mai 21 15:36:31 rpi-3 systemd[1]: Stopped OpenBSD Secure Shell server.
A fatal error in the output!
It means that it does not have the initial credentials in the machine. Let’s add
it with ssh-keygen -A:
sudo ssh-keygen -A
ssh-keygen: generating new host keys: RSA DSA
ECDSA ED25519
Done! Now let’s restart the ssh service:
sudo service ssh restart
Rechecking the service status:
sudo service ssh status
● ssh.service - OpenBSD Secure Shell server
Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2021-05-21 15:42:57 -03; 2s ago
Process: 2101 ExecReload=/bin/kill -HUP $MAINPID (code=exited, status=0/SUCCESS)
Process: 2095 ExecReload=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Process: 3405 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
Main PID: 3406 (sshd)
Tasks: 1 (limit: 2029)
CGroup: /system.slice/ssh.service
└─3406 /usr/sbin/sshd -D
mai 21 15:42:57 rpi-3 systemd[1]: Starting OpenBSD Secure Shell server...
mai 21 15:42:57 rpi-3 sshd[3406]: Server listening on 0.0.0.0 port 22.
mai 21 15:42:57 rpi-3 sshd[3406]: Server listening on :: port 22.
mai 21 15:42:57 rpi-3 systemd[1]: Started OpenBSD Secure Shell server.
Now it works! 🚀