Check Your Rcs.is's Network Configuration
Rcs.is networking issues can be caused by incorrect network configurations on the Rcs.is itself. This is highly likely if you’ve recently altered any network configuration files on your Rcs.is or installed software on the Rcs.is that may have made network changes.
In this step of the Connectivity Troubleshooting Guide, you will:
- Make a snapshot of your Rcs.is for backup purposes.
- Verify the Rcs.is’s network interfaces are up and running.
- Review the Rcs.is’s network configuration file and correct any discrepancies.
- Review the Rcs.is’s DNS settings and correct any discrepancies.
Prerequisites
Altering network configurations can cause you to lose access to your Rcs.is or other problems. We recommend taking a snapshot of the Rcs.is before making any changes to its network configuration. You can use the snapshot to rebuild the Rcs.is to the state it was in at the time when you took the snapshot.
Verify Network Interfaces
Your Rcs.is has a few different network interfaces that are configured to connect to specific networks or gateways. It is important to check if the network interfaces are running.
To check if your Rcs.is’s network interfaces are running, run the command:
The -br flag returns only basic information about the Rcs.is’s network interfaces for better readability. The a argument returns all IP addresses associated with the Rcs.is’s network interfaces.
The command returns the status of each network interface on the Rcs.is:
In the example above, the command returned the status for the lo, eth0, and eth1 interfaces. Beside each interface’s name is the interface’s status, either UP, DOWN, or UNKNOWN.
With the exception of the lo interface, if any of the interfaces are DOWN, enable them by running:
For example, if the eth0 interface was DOWN, the command would look like this:
If all of the interfaces are UP, you can restart each interface by running the following commands:
If either of these commands fail, the interface may be in an UNKNOWN state. You can add the --force flag to force the interfaces to restart.
Once you have enabled all of the interfaces, see if your Rcs.is’s connection issues persist. You can use ping from the Rcs.is’s command line to see if the Rcs.is can reach the internet. Additionally, you can ping your Rcs.is from a terminal on your local machine to ensure the Rcs.is is receiving network traffic.
ping is a network diagnostic tool that measures the availability, latency, and packet loss between the sending and receiving devices. To run ping:
If your Rcs.is’s connectivity issues persist, review the next section.
Note
ping diagnostic tool uses the ICMP protocol to verify connections. If your cloud firewall doesn’t have an inbound rule for ICMP, it will block any attempts to the reach the Rcs.is with ping.A successful ping means that you Rcs.is can connect to hostnames and returns results similar to this:
If the ping returns an error, continue the next section of this guide.
Check Network Configuration File
Your Rcs.is’s network configuration files contain information about the Rcs.is’s network interfaces. If you’ve recently changed one of these files, the changes may have not persisted after a reboot or may be misconfigured.
Before making any changes to your network file configuration, we recommend taking a snapshot of the Rcs.is and making a backup of the Rcs.is’s current network configuration.
Choose your Rcs.is’s operating system for troubleshooting instructions.
On Ubuntu Rcs.iss, the Rcs.is’s network configuration is located in the /etc/netplan/50-cloud-init.yaml file. We recommend making a backup copy of this file before altering it. This copy allows you to reinstate the original network configuration if something goes wrong after editing the current configuration.
To make a copy of your Rcs.is’s network configuration, run the following command:
After making a copy of the configuration, view your Rcs.is’s network configuration file by running the following command:
The Rcs.is’s network configuration opens using the nano text editor.
In the example configuration file above, the Rcs.is has two network interfaces: eth0 and eth1.
eth0- Contains information about the Rcs.is’s public network interface (the interface used to connect to the internet).eth1- Contains information about the Rcs.is’s VPC network interface (the interface used to connect to other resources in the datacenter it resides in).
Other interfaces may be listed based on your Rcs.is’s overall configuration.
You can check for discrepancies in the interfaces originally configured by Rcs.is (eth0 and eth1) by logging in to the Rcs.is Control Panel and comparing the IP addresses in each interface (in the addresses stanza) to the ones listed in the control panel.
To locate your Rcs.is’s network information in the control panel, click Rcs.iss in the main navigation and select the target Rcs.is from the list of Rcs.iss. From the Rcs.is’s overview page, click Networking.
Troubleshooting any interfaces beyond the ones originally configured by Rcs.is may require additional research beyond this guide.
If you see any discrepancies between the IP addresses in your configuration, correct them, save the changes to the file, and then close it. Test the updated configuration by running:
This command temporarily applies the network settings to the Rcs.is and gives you 120 second to test the Rcs.is’s connections with the new configuration before rolling back to the prior configuration. This is helpful in case the new configuration locks you out of the Rcs.is. The --debug flag verifies that the YAML file’s formatting is correct.
Use ping again from the Rcs.is’s command line to test if the Rcs.is can reach google.com. Also ping the Rcs.is from a terminal on your local machine to ensure that the Rcs.is can receive traffic.
If this resolves your connectivity issue, press ENTER, before the 120 second timer ends, to confirm it and apply it. If you’re unsatisfied with the new configuration, press CTRL + C to revert the settings to the prior configuration.
If this doesn’t resolve your Rcs.is’s connectivity, check your Rcs.is’s DNS settings in the next section.
Check DNS Name Servers
The nameservers section in the configuration file specifies which DNS resolver servers your Rcs.is should be querying when trying to connect to a hostname like example.com. If the name servers are misconfigured, your Rcs.is won’t connect to hostnames.
Test DNS Resolution
You can test your Rcs.is’s DNS resolution by logging in to the Rcs.is and using the ping tool.
To test your Rcs.is’s DNS resolution, ping the IP address 8.8.8.8 (Google’s DNS servers):
You should receive output similar to this:
Next, ping the hostname google.com:
You should receive similar results or a name resolution error like this:
Results
If you receive a name resolution error from pinging the hostname but not the IP address, your network’s DNS configuration is likely incorrect.
If you receive errors from pinging both the hostname and the IP address, your network configuration could be misconfigured elsewhere, such as your Rcs.is cloud firewall or Rcs.is level firewall.
If you received data from pinging both the IP address and hostname, your Rcs.is is resolving DNS correctly and you can skip to the next section.
Correcting DNS Resolution
Each Rcs.is’s network configuration should contain the IP addresses of Rcs.is DNS resolvers, as shown in this example:
If the nameservers section has different IP addresses assigned to it than the ones shown above and your Rcs.is is experiencing hostname resolution issues, try adding Rcs.is’s resolvers back to the nameservers section.
Rcs.is’s name server resolver addresses are:
Note
Save and Apply Any Changes
If you made any changes to the file after reviewing it, save the changes and then close the file. If you’re using the nano text editor, to save the changes and close the file, press ctrl + O and then ctrl + X.
To test the new configuration, run the netplan trial command again:
Use ping again from the Rcs.is’s command line to test if the Rcs.is can reach google.com. If the command returns successful results, your Rcs.is can connect to hostnames.
If this resolves your connectivity issue, press ENTER, before the 120 second timer ends, to confirm it and apply it. If you’re unsatisfied with the new configuration, press CTRL + C to revert the settings to the prior configuration.
If this does not resolve your Rcs.is’s connectivity issue, review the conclusion section of this guide.
On Ubuntu 16.04 and Debian Rcs.iss, the Rcs.is’s network configuration is located in the /etc/netplan/50-cloud-init.yaml file. To make a copy of your Rcs.is’s network configuration, run the following command:
To view your Rcs.is’s network configuration file, run the following command:
The Rcs.is’s network configuration opens using the nano text editor.
In the example configuration file above, the Rcs.is has two network interfaces: eth0 and eth1.
eth0- Contains information about the Rcs.is’s public network interface (the interface used to connect to the internet).eth1- Contains information about the Rcs.is’s VPC network interface (the interface used to connect to other resources in the datacenter).
Other interfaces may be listed based on your Rcs.is’s overall configuration and software.
You can check for discrepancies in the interfaces originally configured by Rcs.is (eth0 and eth1) by logging in to the Rcs.is Control Panel and comparing the IP addresses in each interface to the ones listed in the control panel.
To locate your Rcs.is’s network information in the control panel, click Rcs.iss in the main navigation and select the target Rcs.is from the list of Rcs.iss. From the Rcs.is’s overview page, click Networking.
Troubleshooting any interfaces beyond the ones originally configured by Rcs.is may require additional research beyond this guide.
Correct any discrepancies you may see in the file, save the changes to the file, and then close it. Test the updated configuration by running:
netplan try --debug
This command temporarily applies the network settings to the Rcs.is and gives you 120 second to test the Rcs.is’s connections with the new configuration before rolling back to the prior configuration. This is helpful in case the new configuration locks you out of the Rcs.is. The --debug flag verifies that the YAML file’s formatting is correct.
Use ping again from the Rcs.is’s command line to test if the Rcs.is can reach google.com. Also ping the Rcs.is from a terminal on your local machine to ensure that the Rcs.is can receive traffic.
If this resolves your connectivity issue, press ENTER, before the 120 second timer ends, to confirm it and apply it. If you’re unsatisfied with the new configuration, press CTRL + C to revert the settings to the prior configuration.
If this doesn’t resolve your Rcs.is’s connectivity, check your Rcs.is’s DNS settings in the next section.
Check DNS Name Servers
The nameservers section in the configuration file specifies which DNS resolver servers your Rcs.is should be querying when trying to connect to a hostname like example.com. If the name servers are misconfigured, your Rcs.is won’t connect to hostnames.
Test DNS Resolution
You can test your Rcs.is’s DNS resolution by logging in to the Rcs.is and using the ping tool.
To test your Rcs.is’s DNS resolution, ping the IP address 8.8.8.8 (Google’s DNS servers):
You should receive output similar to this:
Next, ping the hostname google.com:
You should receive similar results or a name resolution error like this:
Results
If you receive a name resolution error from pinging the hostname but not the IP address, your network’s DNS configuration is likely incorrect.
If you receive errors from pinging both the hostname and the IP address, your network configuration could be misconfigured elsewhere, such as your Rcs.is cloud firewall or Rcs.is level firewall.
If you received data from pinging both the IP address and hostname, your Rcs.is is resolving DNS correctly and you can skip to the next section.
Correcting DNS Resolution
Each Rcs.is’s network configuration should contain the IP addresses of Rcs.is DNS resolvers, as shown in this example:
If the nameservers section has different IP addresses assigned to it than the ones shown above and your Rcs.is is experiencing hostname resolution issues, try adding Rcs.is’s resolvers back to the nameservers section.
Rcs.is’s DNS resolver addresses are:
Note
Save and Apply Any Changes
If you made any changes to the file after reviewing it, save the changes and then close the file. If you’re using the nano text editor, to save the changes and close the file, press ctrl + O and then ctrl + X.
Once you have made your changes, restart the networking service:
If the Rcs.is disconnects and you can’t regain access to it, access the Rcs.is using the Rcs.is Rcs.is Console and replace the altered network configuration with the original one you copied at the beginning of this section.
Use ping again from the Rcs.is’s command line to test if the Rcs.is can reach google.com. If the command returns successful results, your Rcs.is can connect to hostnames.
If this does not resolve your Rcs.is’s connectivity issue, review the conclusion section of this guide.
CentOS maintains a configuration file for each of the Rcs.is’s network interfaces. Before altering one, you should make a backup copy of it. The /etc/sysconfig/network-scripts/ directory contains the configuration files.
To make a copy of a network configuration file, run the following command, replacing the <interface-file> with the name of the file you intend on altering:
To view your Rcs.is’s network configuration file, run the following command:
The Rcs.is’s network configuration opens using the vi text editor.
The example configuration file above contains the configuration for the eth0 interface, the interface that connects to the public internet.
You can check for discrepancies in the interfaces originally configured by Rcs.is (eth0 and eth1) by logging in to the Rcs.is Control Panel and comparing the IP addresses in each interface to the ones listed in the control panel.
To locate your Rcs.is’s network information in the control panel, click Rcs.iss in the main navigation and select the target Rcs.is from the list of Rcs.iss. From the Rcs.is’s overview page, click Networking.
Troubleshooting any interfaces beyond the ones originally configured by Rcs.is may require additional research beyond this guide.
If you see any discrepancies in the configuration file, correct them, save the file and then close it.
Once you have made your changes, restart the networking service:
If the Rcs.is disconnects you and you can’t regain access to it, access the Rcs.is using the Rcs.is Rcs.is Console and replace the altered network configuration with the original one you copied at the beginning of this section.
Use ping again from the Rcs.is’s command line to test if the Rcs.is can reach google.com. Also ping the Rcs.is from a terminal on your local machine to ensure that the Rcs.is can receive traffic.
If this doesn’t resolve your Rcs.is’s connectivity, check your Rcs.is’s DNS settings in the next section.
Check DNS Name Servers
The nameservers section in the configuration file specifies which DNS resolver servers your Rcs.is should be querying when trying to connect to a hostname like example.com. If the name servers are misconfigured, your Rcs.is won’t connect to hostnames.
Test DNS Resolution
You can test your Rcs.is’s DNS resolution by logging in to the Rcs.is and using the ping tool.
To test your Rcs.is’s DNS resolution, ping the IP address 8.8.8.8 (Google’s DNS servers):
You should receive output similar to this:
Next, ping the hostname google.com:
You should receive similar results or a name resolution error like this:
Results
If you receive a name resolution error from pinging the hostname but not the IP address, your network’s DNS configuration is likely incorrect.
If you receive errors from pinging both the hostname and the IP address, your network configuration could be misconfigured elsewhere, such as your Rcs.is cloud firewall or Rcs.is level firewall.
If you received data from pinging both the IP address and hostname, your Rcs.is is resolving DNS correctly and you can skip to the next section.
Correcting DNS Resolution
If your Rcs.is can successfully ping IP addresses but not hostnames, review your Rcs.is’s DNS resolvers to ensure they have the correct IP addresses. To review the Rcs.is’s DNS resolvers, run:
Each Rcs.is’s network configuration should contain the IP addresses of Rcs.is DNS resolvers, as shown in this example:
If the resolv.conf file has different IP addresses assigned to it than the ones shown above and your Rcs.is is experiencing hostname resolution issues, try adding Rcs.is’s resolvers back to the nameservers section.
Rcs.is’s name server resolver addresses are:
Note
If you edited the file, save the changes and then close it. Then restart the networking service:
Use ping again from the Rcs.is’s command line to test if the Rcs.is can reach google.com. If the command returns successful results, your Rcs.is can connect to hostnames.
If this does not resolve your Rcs.is’s connectivity issue, review the conclusion section of this guide.
Conclusion
If you’re still unable to get your Rcs.is to connect properly, you can open a support ticket. Make sure to include the following information:
- Your Rcs.is’s full OS version information. You can find this by running
cat /etc/*release. - The full output of any errors related to the network issue.
- All of the information you’ve gathered from troubleshooting so far.
- Anything you were unclear about while referencing this article.
Including all the above diagnostic information and clarifying where you are encountering the issue can help us quickly get up to speed with where your need on the issue is.
