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SSH connection has been working properly, but today unfortunately it stopped.

I had lots of tries to solve it.

linux@mylinux:~$ ssh root@XX.XX.XXX.XXX

ssh: connect to host XX.XX.XXX.XXX port 22: Connection refused

linux@mylinux:~$ ssh root@XX.XX.XXX.XXX -p 8787

ssh: connect to host XX.XX.XXX.XXX port 8787: Connection refused

>>>linux@mylinux:~$ ssh root@XX.XX.XXX.XXX -vvv

OpenSSH_7.4p1 Ubuntu-10, OpenSSL 1.0.2g  1 Mar 2016

debug1: Reading configuration data /etc/ssh/ssh_config

debug1: /etc/ssh/ssh_config line 19: Applying options for *

debug2: resolving "XX.XX.XXX.XXX" port 22

debug2: ssh_connect_direct: needpriv 0

debug1: Connecting to XX.XX.XXX.XXX [XX.XX.XXX.XXX] port 22.

debug1: connect to address XX.XX.XXX.XXX port 22: Connection refused

ssh: connect to host XX.XX.XXX.XXX port 22: Connection refused



ssh - status



>● ssh.service - OpenBSD Secure Shell server

   Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)

   Active: active (running) since Sat 2017-11-18 15:42:28 IST; 31min ago

 Main PID: 6940 (sshd)

    Tasks: 1 (limit: 4915)

   CGroup: /system.slice/ssh.service

           └─6940 /usr/sbin/sshd -D

Also, I have removed openssh-sever and reinstalled it, but it can not succeed.

When I try to connect via localhost then it is a success, but on a remote site it is refused.

But I still can not succeed.

Why is my SSH connection refused?

cat /etc/ssh/sshd_config



Host *



*#    $OpenBSD: sshd_config,v 1.100 2016/08/15 12:32:04 naddy Exp $



*# This is the sshd server system-wide configuration file.  See

*# sshd_config(5) for more information.



*# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin



*# The strategy used for options in the default sshd_config shipped with

*# OpenSSH is to specify options with their default value where

*# possible, but leave them commented.  Uncommented options override the

*# default value.



*#Port 22

*#AddressFamily any

*#ListenAddress 0.0.0.0

*#ListenAddress ::



*#HostKey /etc/ssh/ssh_host_rsa_key

*#HostKey /etc/ssh/ssh_host_ecdsa_key

*#HostKey /etc/ssh/ssh_host_ed25519_key



*# Ciphers and keying

*#RekeyLimit default none



*# Logging

*#SyslogFacility AUTH

*#LogLevel INFO



*# Authentication:



*#LoginGraceTime 2m

*#PermitRootLogin prohibit-password

*#StrictModes yes

*#MaxAuthTries 6

*#MaxSessions 10



*#PubkeyAuthentication yes



*# Expect .ssh/authorized_keys2 to be disregarded by default in future.

*#AuthorizedKeysFile    .ssh/authorized_keys .ssh/authorized_keys2



*#AuthorizedPrincipalsFile none



*#AuthorizedKeysCommand none

*#AuthorizedKeysCommandUser nobody



*# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts

*#HostbasedAuthentication no

*# Change to yes if you don't trust ~/.ssh/known_hosts for

*# HostbasedAuthentication

*#IgnoreUserKnownHosts no

*# Don't read the user's ~/.rhosts and ~/.shosts files

*#IgnoreRhosts yes



*# To disable tunneled clear text passwords, change to no here!

*#PasswordAuthentication yes

*#PermitEmptyPasswords no



*# Change to yes to enable challenge-response passwords (beware issues with

*# some PAM modules and threads)

ChallengeResponseAuthentication no



*# Kerberos options

*#KerberosAuthentication no

*#KerberosOrLocalPasswd yes

*#KerberosTicketCleanup yes

*#KerberosGetAFSToken no



*# GSSAPI options

*#GSSAPIAuthentication no

*#GSSAPICleanupCredentials yes

*#GSSAPIStrictAcceptorCheck yes

*#GSSAPIKeyExchange no



*# Set this to 'yes' to enable PAM authentication, account processing,

*# and session processing. If this is enabled, PAM authentication will

*# be allowed through the ChallengeResponseAuthentication and

*# PasswordAuthentication.  Depending on your PAM configuration,

*# PAM authentication via ChallengeResponseAuthentication may bypass

*# the setting of "PermitRootLogin without-password".

*# If you just want the PAM account and session checks to run without

*# PAM authentication, then enable this but set PasswordAuthentication

*# and ChallengeResponseAuthentication to 'no'.

UsePAM yes



*#AllowAgentForwarding yes

*#AllowTcpForwarding yes

*#GatewayPorts no

X11Forwarding yes

*#X11DisplayOffset 10

*#X11UseLocalhost yes

*#PermitTTY yes

PrintMotd no

*#PrintLastLog yes

*#TCPKeepAlive yes

*#UseLogin no

*#UsePrivilegeSeparation sandbox

*#PermitUserEnvironment no

*#Compression delayed

*#ClientAliveInterval 0

*#ClientAliveCountMax 3

*#UseDNS no

*#PidFile /var/run/sshd.pid

*#MaxStartups 10:30:100

*#PermitTunnel no

*#ChrootDirectory none

*#VersionAddendum none



*# no default banner path

*#Banner none



*# Allow client to pass locale environment variables

AcceptEnv LANG LC_*



*# override default of no subsystems

Subsystem    sftp    /usr/lib/openssh/sftp-server



*# Example of overriding settings on a per-user basis

*#Match User anoncvs

*#    X11Forwarding no

*#    AllowTcpForwarding no

*#    PermitTTY no

*#    ForceCommand cvs server

Here

sudo netstat -tlpena | grep -i "ssh"

tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      0          25237      1260/sshd

tcp6       0      0 :::22                   :::*                    LISTEN      0          25239      1260/sshd

AND

sudo iptables -S

-P INPUT DROP

-P FORWARD DROP

-P OUTPUT ACCEPT

-N ufw-after-forward

-N ufw-after-input

-N ufw-after-logging-forward

-N ufw-after-logging-input

-N ufw-after-logging-output

-N ufw-after-output

-N ufw-before-forward

-N ufw-before-input

-N ufw-before-logging-forward

-N ufw-before-logging-input

-N ufw-before-logging-output

-N ufw-before-output

-N ufw-logging-allow

-N ufw-logging-deny

-N ufw-not-local

-N ufw-reject-forward

-N ufw-reject-input

-N ufw-reject-output

-N ufw-skip-to-policy-forward

-N ufw-skip-to-policy-input

-N ufw-skip-to-policy-output

-N ufw-track-forward

-N ufw-track-input

-N ufw-track-output

-N ufw-user-forward

-N ufw-user-input

-N ufw-user-limit

-N ufw-user-limit-accept

-N ufw-user-logging-forward

-N ufw-user-logging-input

-N ufw-user-logging-output

-N ufw-user-output

-A INPUT -j ufw-before-logging-input

-A INPUT -j ufw-before-input

-A INPUT -j ufw-after-input

-A INPUT -j ufw-after-logging-input

-A INPUT -j ufw-reject-input

-A INPUT -j ufw-track-input

-A FORWARD -j ufw-before-logging-forward

-A FORWARD -j ufw-before-forward

-A FORWARD -j ufw-after-forward

-A FORWARD -j ufw-after-logging-forward

-A FORWARD -j ufw-reject-forward

-A FORWARD -j ufw-track-forward

-A OUTPUT -j ufw-before-logging-output

-A OUTPUT -j ufw-before-output

-A OUTPUT -j ufw-after-output

-A OUTPUT -j ufw-after-logging-output

-A OUTPUT -j ufw-reject-output

-A OUTPUT -j ufw-track-output

-A ufw-after-input -p udp -m udp --dport 137 -j ufw-skip-to-policy-input

-A ufw-after-input -p udp -m udp --dport 138 -j ufw-skip-to-policy-input

-A ufw-after-input -p tcp -m tcp --dport 139 -j ufw-skip-to-policy-input

-A ufw-after-input -p tcp -m tcp --dport 445 -j ufw-skip-to-policy-input

-A ufw-after-input -p udp -m udp --dport 67 -j ufw-skip-to-policy-input

-A ufw-after-input -p udp -m udp --dport 68 -j ufw-skip-to-policy-input

-A ufw-after-input -m addrtype --dst-type BROADCAST -j ufw-skip-to-policy-input

-A ufw-after-logging-forward -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "

-A ufw-after-logging-input -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "

-A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

-A ufw-before-forward -p icmp -m icmp --icmp-type 3 -j ACCEPT

-A ufw-before-forward -p icmp -m icmp --icmp-type 4 -j ACCEPT

-A ufw-before-forward -p icmp -m icmp --icmp-type 11 -j ACCEPT

-A ufw-before-forward -p icmp -m icmp --icmp-type 12 -j ACCEPT

-A ufw-before-forward -p icmp -m icmp --icmp-type 8 -j ACCEPT

-A ufw-before-forward -j ufw-user-forward

-A ufw-before-input -i lo -j ACCEPT

-A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

-A ufw-before-input -m conntrack --ctstate INVALID -j ufw-logging-deny

-A ufw-before-input -m conntrack --ctstate INVALID -j DROP

-A ufw-before-input -p icmp -m icmp --icmp-type 3 -j ACCEPT

-A ufw-before-input -p icmp -m icmp --icmp-type 4 -j ACCEPT

-A ufw-before-input -p icmp -m icmp --icmp-type 11 -j ACCEPT

-A ufw-before-input -p icmp -m icmp --icmp-type 12 -j ACCEPT

-A ufw-before-input -p icmp -m icmp --icmp-type 8 -j ACCEPT

-A ufw-before-input -p udp -m udp --sport 67 --dport 68 -j ACCEPT

-A ufw-before-input -j ufw-not-local

-A ufw-before-input -d 224.0.0.251/32 -p udp -m udp --dport 5353 -j ACCEPT

-A ufw-before-input -d 239.255.255.250/32 -p udp -m udp --dport 1900 -j ACCEPT

-A ufw-before-input -j ufw-user-input

-A ufw-before-output -o lo -j ACCEPT

-A ufw-before-output -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

-A ufw-before-output -j ufw-user-output

-A ufw-logging-allow -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW ALLOW] "

-A ufw-logging-deny -m conntrack --ctstate INVALID -m limit --limit 3/min --limit-burst 10 -j RETURN

-A ufw-logging-deny -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "

-A ufw-not-local -m addrtype --dst-type LOCAL -j RETURN

-A ufw-not-local -m addrtype --dst-type MULTICAST -j RETURN

-A ufw-not-local -m addrtype --dst-type BROADCAST -j RETURN

-A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j ufw-logging-deny

-A ufw-not-local -j DROP

-A ufw-skip-to-policy-forward -j DROP

-A ufw-skip-to-policy-input -j DROP

-A ufw-skip-to-policy-output -j ACCEPT

-A ufw-track-output -p tcp -m conntrack --ctstate NEW -j ACCEPT

-A ufw-track-output -p udp -m conntrack --ctstate NEW -j ACCEPT

-A ufw-user-input -p tcp -m tcp --dport 22 -j ACCEPT

-A ufw-user-limit -m limit --limit 3/min -j LOG --log-prefix "[UFW LIMIT BLOCK] "

-A ufw-user-limit -j REJECT --reject-with icmp-port-unreachable

-A ufw-user-limit-accept -j ACCEPT

Edit your sshd config with:

Port 22

PermitRootLogin yes

and restart sshd service. Also, not sure why your lines starts with *, is that a formatting issue?
If there are * on sshd config please do sed -i 's/^*//g' /etc/ssh/sshd_config