You haven't installed any blocking software like fail2ban have you?

It could be possible you have blocked your computer some how ether in the denied host file or through iptables or some kind of blocking software like fail2ban. try to connect using a different computer system.

Also run this and report back.

sudo grep -R "Received disconnect" log/

No installations. Also the denyhosts file is empty. And its just not my machine. I tried from a different network, and also from a different IP altogether. As a matter of fact I even got 2 people to try logging in from 2 different countries. And they reported the same error. Tried all ends and still clueless.

And regarding your command I get an error
grep: log/: No such file or directory

Looking at your sshd_config file everything looks good.

Any chance your not using the correct root password.

sudo grep -R "Received disconnect" /var/log/

sorry add /var/log

Firstly I am extremely grateful for your replies and patience. Thanks a lot.

Regarding the wrong password, I tried that as well. Thinking the password got reset for some reason, I tried reseting the password after powering off the linode, but no good. The same error persisted.

Regarding the Recieved disconnect here goes the out put

/var/log/auth.log:May 4 01:19:13 inovvorx sudo: root : TTY=hvc0 ; PWD=/root ; USER=root ; COMMA
ND=/bin/grep -R Recieved disconnect log/
/var/log/auth.log:May 4 01:19:22 inovvorx sudo: root : TTY=hvc0 ; PWD=/root ; USER=root ; COMMA
ND=/bin/grep -R Recieved disconnect log
/var/log/auth.log:May 4 01:20:07 inovvorx sudo: root : TTY=hvc0 ; PWD=/root ; USER=root ; COMMA
ND=/bin/grep -R Recieved disconnectlog/
/var/log/auth.log:May 4 01:23:05 inovvorx sudo: root : TTY=hvc0 ; PWD=/root ; USER=root ; COMMA
ND=/bin/grep -R Recieved disconnectlog/
/var/log/auth.log:May 4 01:24:34 inovvorx sudo: root : TTY=hvc0 ; PWD=/root ; USER=root ; COMMA
ND=/bin/grep -R Recieved disconnect /var/log/

I'm running out of ideals

Is there anyway to clear the current SSH configuration and configure it all over again? I dont see any other option.

to be honest I don't think its a ssh issue... add a new user and try to log in

In your /etc/ssh/sshd_config, change

LogLevel INFO

to:

LogLevel Debug

then try and connect again. After it fails (or works!), look in /var/log/auth.log and copy and paste the relevant lines.

Don't forget to revert the LogLevel change after we're done.

Restart ssh after changing the loglevel using service ssh restart

_________________
Paid support
How to ask for help
1. Give details of your problem
2. Post any errors
3. Post relevant logs.
4. Don't hide details i.e. your domain, it just makes things harder
5. Be polite or you'll be eaten by a grue

The last few relevant lines of the auth.log file after setting it to debug is mentioned below.

May 4 10:09:37 inovvorx sshd[3781]: debug1: Bind to port 22 on ::.
May 4 10:09:37 inovvorx sshd[3781]: Server listening on :: port 22.
May 4 10:11:18 inovvorx sshd[3781]: debug1: Forked child 3785.
May 4 10:11:18 inovvorx sshd[3785]: Set /proc/self/oom_adj to -17
May 4 10:11:18 inovvorx sshd[3785]: debug1: rexec start in 5 out 5 newsock 5 pi
pe 7 sock 8
May 4 10:11:18 inovvorx sshd[3785]: debug1: inetd sockets after dupping: 3, 3
May 4 10:11:18 inovvorx sshd[3785]: debug1: Client protocol version 2.0; client
software version PuTTY_Release_0.60
May 4 10:11:18 inovvorx sshd[3785]: debug1: no match: PuTTY_Release_0.60
May 4 10:11:18 inovvorx sshd[3785]: debug1: Enabling compatibility mode for pro
tocol 2.0
May 4 10:11:18 inovvorx sshd[3785]: debug1: Local version string SSH-2.0-OpenSS
H_5.3p1 Debian-3ubuntu7
May 4 10:11:18 inovvorx sshd[3785]: WARNING: /etc/ssh/moduli does not exist, us
ing fixed modulus
May 4 10:11:28 inovvorx sshd[3785]: debug1: PAM: initializing for "root"
May 4 10:11:28 inovvorx sshd[3785]: debug1: PAM: setting PAM_RHOST to "117.192.
40.93"
May 4 10:11:28 inovvorx sshd[3785]: debug1: PAM: setting PAM_TTY to "ssh"
May 4 10:11:28 inovvorx sshd[3785]: Failed none for root from 117.192.40.93 por
t 11378 ssh2

I am still struggling on this one. If anyone can provide some insights, I would be really grateful.

This may not be of any use, but you can reset your sshd to the original configuration by removing it with apt-get purge openssh-server and re-installing with apt-get install openssh-server.

It sounds, however, like somehow your network connection is being cut off before you can transmit the password to the server. Something like fail2ban or denyhosts could do this, as mentioned earlier. You can see your current firewall rules with iptables -nvL.

Since you indicated you did not make any changes to the server configuration, you should also consider the possibility that it has been hacked.

@Vance, Thanks for you reply.

I purged the ssh config and tried re-installing it. However I got an error which read like this

/var/lib/dpkg/info/openssh-server.postinst: 459: cannot create /etc/ssh/sshd_config: Directory nonex
istent
dpkg: error processing openssh-server (--configure):
subprocess installed post-installation script returned error exit status 2
E: Sub-process /usr/bin/dpkg returned an error code (1)

And the problem still persists.

And the problem cant be due to any softwares installed, because the problem isnt for my machine/network alone. Everyone who tries to connect to the server from different locations report the same problem.