Ssh – Accidentally port 22 got closed, how to fix the SSH access

amazon ec2awsssh

Accidentally, Port 22 got closed. I cannot ssh into the instance, though the instance are running well on other desired ports. Getting following error while doing SSH.

ssh: connect to host X.X.X.X port 22: Connection refused

I restarted the instance, but still ssh is not working.
The security groups are open for port 22 from anywhere(0.0.0.0/0).

I was trying to set the default welcome message after SSH on the machine by editing /etc/ssh/sshd_config file. Just after editing and reloading the ssh with the following command I was unable to ssh again.

sudo service ssh reload

Best Answer

I did it by detaching the volume from the current instance than added it to the other instance as a secondary volume. Than the volume become readable, and I changed the ssh config file to default one. Detached the volume and added back to the original instance

Related Solutions

SSH – How to Open a Port Early in Boot Process to Unlock LUKS

I got this same problem a few weeks ago (Debian Wheezy 7.6) and after some days of troubleshooting I found out that there was a config file missing which was preventing to the cryptroot script on init-top to run correctly, hence it was not stopping to ask the password via ssh, killing the dropbear at the end of the sequence (init-bottom).

The config file is called cryptroot and should be under /etc/initramfs-tools/conf.d/ If I am not mistaken that config file should have been created automatically during install (I have read just one tutorial talking about that config file) but somehow it did not (tested in a physical server and in a VM, same OS and versions)

It took me a couple of tries to configure it properly, since I could not find the proper syntax at that time. My cryptroot config file is as follows:

target=crypt-root,source=/dev/vg0/root,lvm=root

Once created the config file just update the initramfs and try again:

update-initramfs -u

SSH server listening on multiple ports with passwordless access not allowing connections to second port

First off, I usually create a second sshd process with its own configuration file. (sshd -f /etc/ssh/sshd-2222.conf for instance) or by overriding the configuration on the command-line (sshd -p 2222 -o PasswordAuthentication=no,AllowRoot=no). This way they share the same keys, etc, but you can override any of the parameters.

Any ideas why this happen?

I have some ideas:

selinux is enabled and is preventing you from using the port to login. This isn't likely, because if the problem were selinux, it wouldn't get that far. Run selinuxenabled && echo "SELinux enabled" && getenforce and if it is enabled and enforced, grep sshd /var/log/audit/audit.log to identify failures. Disable to see if it goes away.
PAM is getting in the way. Again, this doesn't seem likely, since PAM doesn't care about what port you use in conjunction with SSH.
/etc/hosts.allow or /etc/hosts.deny. Here you can associate port-service-user in any number of combinations. If these files are empty, we have to look elsewhere.
Did ssh add some mysterious port number to the key? It's possible. Your logs indicate it is and is not happening. See, for instance:

debug1: Authentication succeeded (publickey). Authenticated to localhost ([127.0.0.1]:5984).

From the changelog in CentOS7:

* Fri Oct 26 2012 Petr Lautrbach <plautrba@redhat.com> 6.1p1-2
  - add SELinux comment to /etc/ssh/sshd_config about SELinux command to modify port (#861400)

OK, so maybe it is selinux.

Best Answer

Related Solutions

SSH – How to Open a Port Early in Boot Process to Unlock LUKS

SSH server listening on multiple ports with passwordless access not allowing connections to second port

Related Question