I want to make some minor configuration changes.

To change the configuration of a device in the GNS3 project, the usual procedure is to enter a configuration command from the CLI and save the configuration with copy running-config startup-config.

In addition to the usual procedure, you can also edit the device’s startup-config directly. This is handy if you want to make a small configuration change and you don’t have to boot up the device and enter a command from the CLI.

How to edit startup-config directly

The steps to edit startup-config directly are as follows

  1. Open the device startup-config from [Edit config]
  2. Edit the contents of startup-config and click [Save]

Open the device startup-config from [Edit config]

Open the GNS3 project and right-click on the device you want to edit startup-config, then click [Edit config].

You will then see a box with the name of the device’s startup-config file. Click OK to move to the startup-config edit window.

Edit the contents of startup-config and click [Save]

You can freely edit the contents of startup-config. Commands do not have to be spelled in full. The order of the commands doesn’t matter either, except for a few commands that have dependencies. There is no need to indent them with spaces. However, make sure that the command syntax is correct, because if you make a mistake, it won’t be recognized.

When the editing is complete, just click [Save] to save it. When the device is started, it will start up with the edited startup-config loaded.

I want to edit startup-config in a familiar text editor

It is also possible to edit startup-config in your favorite text editor. Here are the steps to do so

  1. Open the device’s startup-config with any text editor
  2. Edit startup-config and save it.

Open the device’s startup-config with any text editor

Right-click a device and click “show in file manager” to open a folder that holds the various files that emulate that device.

The [configs] folder contains a startup-config with a .cfg extension. Open startup-config with any text editor.

Edit startup-config and save it.

All you have to do now is edit the contents of startup-config in your familiar text editor and save it at the end.

How to use GNS3