I recently installed WireGuard so I can tunnel DNS request to the VPN. I also have portsentry and fail2ban but now I disabled them until I find the solution to the problem.
When I login into my user in ssh, everything is ok. But I have to wait several minutes before the second login, even if I close the first connection, if not it tries a long time to connect but the connection is timed out. I have this problem only on wan, not on lan. In other device (a smartphone) I can check that if I disable the VPN I can login several times without problems. But what is really weird is that in my pc, even if I disable the VPN I have the same problem (and DNS without VPN are 22.214.171.124 and 126.96.36.199).
/var/log/auth.log I could see the warning
"POSSIBLE BREAK-IN ATTEMPT!" pointing to my IP. So, it must be a DNS reverse advice.
I disabled these warnings adding
UseDNS no to the system's
I still have this second login problem even now.
Some other information:
iptables is not banning my IP and after a
iptables -FI have the same problem.
The IP is not in the
# What ports, IPs and protocols we listen for Port "myport" # Use these options to restrict which interfaces/protocols sshd will bind to #ListenAddress :: #ListenAddress 0.0.0.0 Protocol 2 # HostKeys for protocol version 2 HostKey /etc/ssh/ssh_host_rsa_key HostKey /etc/ssh/ssh_host_dsa_key HostKey /etc/ssh/ssh_host_ecdsa_key #Privilege Separation is turned on for security UsePrivilegeSeparation yes # Lifetime and size of ephemeral version 1 server key KeyRegenerationInterval 3600 ServerKeyBits 1024 # Logging SyslogFacility AUTH LogLevel INFO # Authentication: LoginGraceTime 120 PermitRootLogin no StrictModes yes RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile %h/.ssh/authorized_keys # Don't read the user's ~/.rhosts and ~/.shosts files IgnoreRhosts yes # For this to work you will also need host keys in /etc/ssh_known_hosts RhostsRSAAuthentication no # similar for protocol version 2 HostbasedAuthentication no # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication #IgnoreUserKnownHosts yes # To enable empty passwords, change to yes (NOT RECOMMENDED) PermitEmptyPasswords no # Change to yes to enable challenge-response passwords (beware issues with # some PAM modules and threads) ChallengeResponseAuthentication yes # Change to no to disable tunnelled clear text passwords PasswordAuthentication yes # Kerberos options #KerberosAuthentication no #KerberosGetAFSToken no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes # GSSAPI options #GSSAPIAuthentication yes #GSSAPICleanupCredentials yes X11Forwarding yes X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes #UseLogin no #MaxStartups 10:30:60 #Banner /etc/issue.net # Allow client to pass locale environment variables AcceptEnv LANG LC_* Subsystem sftp /usr/lib/openssh/sftp-server # 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 # Only allow "myuser" AllowUsers "myuser" # Allow DNS reverse (wireguard) UseDNS no
where "myport" and "myuser" are my port and user data.
How can I check what is wrong?