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We Were Unable to Connect to Your Server

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Troubleshoot connecting to your instance

The following information can help you troubleshoot issues with connecting to your instance. For additional help with Windows instances, see Troubleshoot Windows instances in the Amazon EC2 User Guide for Windows Instances.

Common causes for connection issues

We recommend that you begin troubleshooting by checking some common causes for issues connecting to your instance.

Verify the user name for your instance

You can connect to your instance using the user name for your user account or the default user name for the AMI that you used to launch your instance.

  • Get the user name for your user account.

    For more information about how to create a user account, see Manage user accounts on your Amazon Linux instance.

  • Get the default user name for the AMI that you used to launch your instance:

    • For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.

    • For a CentOS AMI, the user name is centos or ec2-user.

    • For a Debian AMI, the user name is admin.

    • For a Fedora AMI, the user name is fedora or ec2-user.

    • For a RHEL AMI, the user name is ec2-user or root.

    • For a SUSE AMI, the user name is ec2-user or root.

    • For an Ubuntu AMI, the user name is ubuntu.

    • For an Oracle AMI, the user name is ec2-user.

    • For a Bitnami AMI, the user name is bitnami.

    • Otherwise, check with the AMI provider.

Verify that your security group rules allow traffic

Make sure your security group rules allow inbound traffic from your public IPv4 address on the proper port. For steps to verify, see Error connecting to your instance: Connection timed out

Verify that your instance is ready

After you launch an instance, it can take a few minutes for the instance to be ready so that you can connect to it. Check your instance to make sure it is running and has passed its status checks.

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances, and then select your instance.

  3. Verify the following:

    1. In the Instance state column, verify that your instance is in the running state.

    2. In the Status check column, verify that your instance has passed the two status checks.

Verify the general prerequisites for connecting to your instance

For more information, see General prerequisites for connecting to your instance.

Error connecting to your instance: Connection timed out

If you try to connect to your instance and get an error message Network error: Connection timed out or Error connecting to [instance], reason: -> Connection timed out: connect, try the following:

Check your security group rules.

You need a security group rule that allows inbound traffic from your public IPv4 address on the proper port.

New console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances, and then select your instance.

  3. On the Security tab at the bottom of the console page, under Inbound rules, check the list of rules that are in effect for the selected instance.

    • For Linux instances: Verify that there is a rule that allows traffic from your computer to port 22 (SSH).

    • For Windows instances: Verify that there is a rule that allows traffic from your computer to port 3389 (RDP).

  4. Each time you restart your instance, a new IP address (and host name) will be assigned. If your security group has a rule that allows inbound traffic from a single IP address, this address might not be static if your computer is on a corporate network or if you are connecting through an internet service provider (ISP). Instead, specify the range of IP addresses used by client computers. If your security group does not have a rule that allows inbound traffic as described in the previous step, add a rule to your security group. For more information, see Authorize inbound traffic for your Linux instances.

    For more information about security group rules, see Security group rules in the Amazon VPC User Guide.

Old console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances, and then select your instance.

  3. In the Description tab at the bottom of the console page, next to Security groups, select view inbound rules to display the list of rules that are in effect for the selected instance.

  4. For Linux instances: When you select view inbound rules, a window will appear that displays the port(s) to which traffic is allowed. Verify that there is a rule that allows traffic from your computer to port 22 (SSH).

    For Windows instances: When you select view inbound rules, a window will appear that displays the port(s) to which traffic is allowed. Verify that there is a rule that allows traffic from your computer to port 3389 (RDP).

    Each time you restart your instance, a new IP address (and host name) will be assigned. If your security group has a rule that allows inbound traffic from a single IP address, this address may not be static if your computer is on a corporate network or if you are connecting through an internet service provider (ISP). Instead, specify the range of IP addresses used by client computers. If your security group does not have a rule that allows inbound traffic as described in the previous step, add a rule to your security group. For more information, see Authorize inbound traffic for your Linux instances.

    For more information about security group rules, see Security group rules in the Amazon VPC User Guide.

Check the route table for the subnet.

You need a route that sends all traffic destined outside the VPC to the internet gateway for the VPC.

New console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances, and then select your instance.

  3. On the Networking tab, make note of the values for VPC ID and Subnet ID.

  4. Open the Amazon VPC console at https://console.aws.amazon.com/vpc/ .

  5. In the navigation pane, choose Internet Gateways. Verify that there is an internet gateway attached to your VPC. Otherwise, choose Create internet gateway, enter a name for the internet gateway, and choose Create internet gateway. Then, for the internet gateway you created, choose Actions, Attach to VPC, select your VPC, and then choose Attach internet gateway to attach it to your VPC.

  6. In the navigation pane, choose Subnets, and then select your subnet.

  7. On the Route table tab, verify that there is a route with 0.0.0.0/0 as the destination and the internet gateway for your VPC as the target. If you're connecting to your instance using its IPv6 address, verify that there is a route for all IPv6 traffic (::/0) that points to the internet gateway. Otherwise, do the following:

    1. Choose the ID of the route table (rtb-xxxxxxxx) to navigate to the route table.

    2. On the Routes tab, choose Edit routes. Choose Add route, use 0.0.0.0/0 as the destination and the internet gateway as the target. For IPv6, choose Add route, use ::/0 as the destination and the internet gateway as the target.

    3. Choose Save routes.

Old console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances, and then select your instance.

  3. In the Description tab, write down the values of VPC ID and Subnet ID.

  4. Open the Amazon VPC console at https://console.aws.amazon.com/vpc/ .

  5. In the navigation pane, choose Internet Gateways. Verify that there is an internet gateway attached to your VPC. Otherwise, choose Create Internet Gateway to create an internet gateway. Select the internet gateway, and then choose Attach to VPC and follow the directions to attach it to your VPC.

  6. In the navigation pane, choose Subnets, and then select your subnet.

  7. On the Route Table tab, verify that there is a route with 0.0.0.0/0 as the destination and the internet gateway for your VPC as the target. If you're connecting to your instance using its IPv6 address, verify that there is a route for all IPv6 traffic (::/0) that points to the internet gateway. Otherwise, do the following:

    1. Choose the ID of the route table (rtb-xxxxxxxx) to navigate to the route table.

    2. On the Routes tab, choose Edit routes. Choose Add route, use 0.0.0.0/0 as the destination and the internet gateway as the target. For IPv6, choose Add route, use ::/0 as the destination and the internet gateway as the target.

    3. Choose Save routes.

Check the network access control list (ACL) for the subnet.

The network ACLs must allow inbound traffic from your local IP address on port 22 (for Linux instances) or port 3389 (for Windows instances). It must also allow outbound traffic to the ephemeral ports (1024-65535).

  1. Open the Amazon VPC console at https://console.aws.amazon.com/vpc/ .

  2. In the navigation pane, choose Subnets.

  3. Select your subnet.

  4. On the Network ACL tab, for Inbound rules, verify that the rules allow inbound traffic from your computer on the required port. Otherwise, delete or modify the rule that is blocking the traffic.

  5. For Outbound rules, verify that the rules allow outbound traffic to your computer on the ephemeral ports. Otherwise, delete or modify the rule that is blocking the traffic.

If your computer is on a corporate network

Ask your network administrator whether the internal firewall allows inbound and outbound traffic from your computer on port 22 (for Linux instances) or port 3389 (for Windows instances).

If you have a firewall on your computer, verify that it allows inbound and outbound traffic from your computer on port 22 (for Linux instances) or port 3389 (for Windows instances).

Check that your instance has a public IPv4 address.

If not, you can associate an Elastic IP address with your instance. For more information, see Elastic IP addresses.

Check the CPU load on your instance; the server may be overloaded.

AWS automatically provides data such as Amazon CloudWatch metrics and instance status, which you can use to see how much CPU load is on your instance and, if necessary, adjust how your loads are handled. For more information, see Monitor your instances using CloudWatch.

  • If your load is variable, you can automatically scale your instances up or down using Auto Scaling and Elastic Load Balancing .

  • If your load is steadily growing, you can move to a larger instance type. For more information, see Change the instance type.

To connect to your instance using an IPv6 address, check the following:

  • Your subnet must be associated with a route table that has a route for IPv6 traffic (::/0) to an internet gateway.

  • Your security group rules must allow inbound traffic from your local IPv6 address on the proper port (22 for Linux and 3389 for Windows).

  • Your network ACL rules must allow inbound and outbound IPv6 traffic.

  • If you launched your instance from an older AMI, it might not be configured for DHCPv6 (IPv6 addresses are not automatically recognized on the network interface). For more information, see Configure IPv6 on Your Instances in the Amazon VPC User Guide.

  • Your local computer must have an IPv6 address, and must be configured to use IPv6.

Error: unable to load key ... Expecting: ANY PRIVATE KEY

If you try to connect to your instance and get the error message, unable to load key ... Expecting: ANY PRIVATE KEY, the file in which the private key is stored is incorrectly configured. If the private key file ends in .pem, it might still be incorrectly configured. A possible cause for an incorrectly configured private key file is a missing certificate.

Error: User key not recognized by server

If you use SSH to connect to your instance

  • Use ssh -vvv to get triple verbose debugging information while connecting: 

                    ssh -vvv -i                  path/my-key-pair.pem                  my-instance-user-name@ec2-203-0-113-25.compute-1.amazonaws.com

    The following sample output demonstrates what you might see if you were trying to connect to your instance with a key that was not recognized by the server: 

                    open/ANT/myusername/.ssh/known_hosts). debug2: bits set: 504/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: boguspem.pem ((nil)) debug1: Authentications that can continue: publickey debug3: start over, passed a different list publickey debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Trying private key: boguspem.pem debug1: read PEM private key done: type RSA debug3: sign_and_send_pubkey: RSA 9c:4c:bc:0c:d0:5c:c7:92:6c:8e:9b:16:e4:43:d8:b2 debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey).

If you use PuTTY to connect to your instance

  • Verify that your private key (.pem) file has been converted to the format recognized by PuTTY (.ppk). For more information about converting your private key, see Connect to your Linux instance from Windows using PuTTY.

    In PuTTYgen, load your private key file and select Save Private Key rather than Generate.

  • Verify that you are connecting with the appropriate user name for your AMI. Enter the user name in the Host name box in the PuTTY Configuration window.

    • For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.

    • For a CentOS AMI, the user name is centos or ec2-user.

    • For a Debian AMI, the user name is admin.

    • For a Fedora AMI, the user name is fedora or ec2-user.

    • For a RHEL AMI, the user name is ec2-user or root.

    • For a SUSE AMI, the user name is ec2-user or root.

    • For an Ubuntu AMI, the user name is ubuntu.

    • For an Oracle AMI, the user name is ec2-user.

    • For a Bitnami AMI, the user name is bitnami.

    • Otherwise, check with the AMI provider.

  • Verify that you have an inbound security group rule to allow inbound traffic to the appropriate port. For more information, see Authorizing Network Access to Your Instances.

Error: Permission denied or connection closed by [instance] port 22

If you connect to your instance using SSH and get any of the following errors, Host key not found in [directory], Permission denied (publickey), Authentication failed, permission denied, or Connection closed by [instance] port 22, verify that you are connecting with the appropriate user name for your AMI and that you have specified the proper private key (.pem) file for your instance.

The appropriate user names are as follows:

  • For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.

  • For a CentOS AMI, the user name is centos or ec2-user.

  • For a Debian AMI, the user name is admin.

  • For a Fedora AMI, the user name is fedora or ec2-user.

  • For a RHEL AMI, the user name is ec2-user or root.

  • For a SUSE AMI, the user name is ec2-user or root.

  • For an Ubuntu AMI, the user name is ubuntu.

  • For an Oracle AMI, the user name is ec2-user.

  • For a Bitnami AMI, the user name is bitnami.

  • Otherwise, check with the AMI provider.

For example, to use an SSH client to connect to an Amazon Linux instance, use the following command: 

          ssh -i            /path/my-key-pair.pem            my-instance-user-name@ec2-203-0-113-25.compute-1.amazonaws.com

Confirm that you are using the private key file that corresponds to the key pair that you selected when you launched the instance.

New console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances and then select your instance.

  3. On the Details tab, under Instance details, verify the value of Key pair name.

  4. If you did not specify a key pair when you launched the instance, you can terminate the instance and launch a new instance, ensuring that you specify a key pair. If this is an instance that you have been using but you no longer have the .pem file for your key pair, you can replace the key pair with a new one. For more information, see Connect to your Linux instance if you lose your private key.

Old console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/ .

  2. In the navigation pane, choose Instances and then select your instance.

  3. In the Description tab, verify the value of Key pair name.

  4. If you did not specify a key pair when you launched the instance, you can terminate the instance and launch a new instance, ensuring that you specify a key pair. If this is an instance that you have been using but you no longer have the .pem file for your key pair, you can replace the key pair with a new one. For more information, see Connect to your Linux instance if you lose your private key.

If you generated your own key pair, ensure that your key generator is set up to create RSA keys. DSA keys are not accepted.

If you get a Permission denied (publickey) error and none of the above applies (for example, you were able to connect previously), the permissions on the home directory of your instance may have been changed. Permissions for /home/my-instance-user-name/.ssh/authorized_keys must be limited to the owner only.

To verify the permissions on your instance

  1. Stop your instance and detach the root volume. For more information, see Stop and start your instance and Detach an Amazon EBS volume from a Linux instance.

  2. Launch a temporary instance in the same Availability Zone as your current instance (use a similar or the same AMI as you used for your current instance), and attach the root volume to the temporary instance. For more information, see Attach an Amazon EBS volume to an instance.

  3. Connect to the temporary instance, create a mount point, and mount the volume that you attached. For more information, see Make an Amazon EBS volume available for use on Linux.

  4. From the temporary instance, check the permissions of the /home/my-instance-user-name/ directory of the attached volume. If necessary, adjust the permissions as follows: 

                                      [ec2-user ~]$                                    chmod 600                    mount_point/home/my-instance-user-name/.ssh/authorized_keys                              
                                      [ec2-user ~]$                                    chmod 700                    mount_point/home/my-instance-user-name/.ssh                              
                                      [ec2-user ~]$                                    chmod 700                    mount_point/home/my-instance-user-name

  5. Unmount the volume, detach it from the temporary instance, and re-attach it to the original instance. Ensure that you specify the correct device name for the root volume; for example, /dev/xvda.

  6. Start your instance. If you no longer require the temporary instance, you can terminate it.

Error: Unprotected private key file

Your private key file must be protected from read and write operations from any other users. If your private key can be read or written to by anyone but you, then SSH ignores your key and you see the following warning message below. 

          @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @         WARNING: UNPROTECTED PRIVATE KEY FILE!          @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Permissions            0777            for '.ssh/my_private_key.pem' are too open. It is required that your private key files are NOT accessible by others. This private key will be ignored. bad permissions: ignore key: .ssh/my_private_key.pem Permission denied (publickey).

If you see a similar message when you try to log in to your instance, examine the first line of the error message to verify that you are using the correct public key for your instance. The above example uses the private key .ssh/my_private_key.pem with file permissions of 0777, which allow anyone to read or write to this file. This permission level is very insecure, and so SSH ignores this key.

If you are connecting from MacOS or Linux, run the following command to fix this error, substituting the path for your private key file. 

                      [ec2-user ~]$                        chmod 0400              .ssh/my_private_key.pem

If you are connecting from Windows, perform the following steps on your local computer.

  1. Navigate to your .pem file.

  2. Right-click on the .pem file and select Properties.

  3. Choose the Security tab.

  4. Select Advanced.

  5. Verify that you are the owner of the file. If not, change the owner to your username.

  6. Select Disable inheritance and Remove all inherited permissions from this object.

  7. Select Add, Select a principal, enter your username, and select OK.

  8. From the Permission Entry window, grant Read permissions and select OK.

  9. Select OK to close the Advanced Security Settings window.

  10. Select OK to close the Properties window.

  11. You should be able to connect to your Linux instance from Windows via SSH.

From a Windows command prompt, run the following commands.

  1. From the command prompt, navigate to the file path location of your .pem file.

  2. Run the following command to reset and remove explicit permissions:

                    icacls.exe                  $path                  /reset

  3. Run the following command to grant Read permissions to the current user:

                    icacls.exe                  $path                  /GRANT:R "$($env:USERNAME):(R)"

  4. Run the following command to disable inheritance and remove inherited permissions.

                    icacls.exe                  $path                  /inheritance:r

  5. You should be able to connect to your Linux instance from Windows via SSH.

Error: Private key must begin with "-----BEGIN RSA PRIVATE KEY-----" and end with "-----END RSA PRIVATE KEY-----"

If you use a third-party tool, such as ssh-keygen, to create an RSA key pair, it generates the private key in the OpenSSH key format. When you connect to your instance, if you use the private key in the OpenSSH format to decrypt the password, you'll get the error Private key must begin with "-----BEGIN RSA PRIVATE KEY-----" and end with "-----END RSA PRIVATE KEY-----".

To resolve the error, the private key must be in the PEM format. Use the following command to create the private key in the PEM format: 

          ssh-keygen -m PEM

Error: Server refused our key or No supported authentication methods available

If you use PuTTY to connect to your instance and get either of the following errors, Error: Server refused our key or Error: No supported authentication methods available , verify that you are connecting with the appropriate user name for your AMI. Type the user name in User name in the PuTTY Configuration window.

The appropriate user names are as follows:

  • For Amazon Linux 2 or the Amazon Linux AMI, the user name is ec2-user.

  • For a CentOS AMI, the user name is centos or ec2-user.

  • For a Debian AMI, the user name is admin.

  • For a Fedora AMI, the user name is fedora or ec2-user.

  • For a RHEL AMI, the user name is ec2-user or root.

  • For a SUSE AMI, the user name is ec2-user or root.

  • For an Ubuntu AMI, the user name is ubuntu.

  • For an Oracle AMI, the user name is ec2-user.

  • For a Bitnami AMI, the user name is bitnami.

  • Otherwise, check with the AMI provider.

You should also verify that your private key (.pem) file has been correctly converted to the format recognized by PuTTY (.ppk). For more information about converting your private key, see Connect to your Linux instance from Windows using PuTTY.

Cannot ping instance

The ping command is a type of ICMP traffic — if you are unable to ping your instance, ensure that your inbound security group rules allow ICMP traffic for the Echo Request message from all sources, or from the computer or instance from which you are issuing the command.

If you are unable to issue a ping command from your instance, ensure that your outbound security group rules allow ICMP traffic for the Echo Request message to all destinations, or to the host that you are attempting to ping.

Ping commands can also be blocked by a firewall or time out due to network latency or hardware issues. You should consult your local network or system administrator for help with further troubleshooting.

Error: Server unexpectedly closed network connection

If you are connecting to your instance with PuTTY and you receive the error "Server unexpectedly closed network connection," verify that you have enabled keepalives on the Connection page of the PuTTY Configuration to avoid being disconnected. Some servers disconnect clients when they do not receive any data within a specified period of time. Set the Seconds between keepalives to 59 seconds.

If you still experience issues after enabling keepalives, try to disable Nagle's algorithm on the Connection page of the PuTTY Configuration.

Error: Host key validation failed for EC2 Instance Connect

If you rotate your instance host keys, the new host keys are not automatically uploaded to the AWS trusted host keys database. This causes host key validation to fail when you try to connect to your instance using the EC2 Instance Connect browser-based client, and you're unable to connect to your instance.

To resolve the error, you must run the eic_harvest_hostkeys script on your instance, which uploads your new host key to EC2 Instance Connect. The script is located at /opt/aws/bin/ on Amazon Linux 2 instances, and at /usr/share/ec2-instance-connect/ on Ubuntu instances.

Amazon Linux 2

To resolve the host key validation failed error on an Amazon Linux 2 instance

  1. Connect to your instance using SSH.

    You can connect by using the EC2 Instance Connect CLI or by using the SSH key pair that was assigned to your instance when you launched it and the default user name of the AMI that you used to launch your instance. For Amazon Linux 2, the default user name is ec2-user.

    For example, if your instance was launched using Amazon Linux 2, your instance's public DNS name is ec2-a-b-c-d.us-west-2.compute.amazonaws.com, and the key pair is my_ec2_private_key.pem, use the following command to SSH into your instance: 

                                                  $                                                ssh -i                          my_ec2_private_key.pem                          ec2-user@ec2-a-b-c-d.us-west-2.compute.amazonaws.com

    For more information about connecting to your instance, see Connect to your Linux instance using SSH.

  2. Navigate to the following folder.

                                                  [ec2-user ~]$                        cd /opt/aws/bin/

  3. Run the following command on your instance.

                                                  [ec2-user ~]$                        ./eic_harvest_hostkeys

    Note that a successful call results in no output.

    You can now use the EC2 Instance Connect browser-based client to connect to your instance.

Ubuntu

To resolve the host key validation failed error on an Ubuntu instance

  1. Connect to your instance using SSH.

    You can connect by using the EC2 Instance Connect CLI or by using the SSH key pair that was assigned to your instance when you launched it and the default user name of the AMI that you used to launch your instance. For Ubuntu, the default user name is ubuntu.

    For example, if your instance was launched using Ubuntu, your instance's public DNS name is ec2-a-b-c-d.us-west-2.compute.amazonaws.com, and the key pair is my_ec2_private_key.pem, use the following command to SSH into your instance: 

                                                  $                                                ssh -i                          my_ec2_private_key.pem                          ubuntu@ec2-a-b-c-d.us-west-2.compute.amazonaws.com

    For more information about connecting to your instance, see Connect to your Linux instance using SSH.

  2. Navigate to the following folder.

                                                  [ec2-user ~]$                        cd /usr/share/ec2-instance-connect/

  3. Run the following command on your instance.

                                                  [ec2-user ~]$                        ./eic_harvest_hostkeys

    Note that a successful call results in no output.

    You can now use the EC2 Instance Connect browser-based client to connect to your instance.

We Were Unable to Connect to Your Server

Source: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstancesConnecting.html

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