---
page-title: "How do I install a root certificate? - Ask Ubuntu"
url: https://askubuntu.com/questions/73287/how-do-i-install-a-root-certificate
date: "2023-03-30 16:38:30"
---

[

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4

Given a CA certificate file `foo.crt`, follow these steps to install it on Ubuntu:

1.  Create a directory for extra CA certificates in `/usr/local/share/ca-certificates`:
    
    ```
    sudo mkdir /usr/local/share/ca-certificates/extra
    ```
    
2.  Copy the CA `.crt` file to this directory:
    
    ```
    sudo cp foo.crt /usr/local/share/ca-certificates/extra/foo.crt
    ```
    
3.  Let Ubuntu add the `.crt` file's path relative to `/usr/local/share/ca-certificates` to `/etc/ca-certificates.conf`:
    
    ```
    sudo dpkg-reconfigure ca-certificates
    ```
    
    To do this non-interactively, run:
    
    ```
    sudo update-ca-certificates
    ```
    

In case of a `.pem` file on Ubuntu, it must first be converted to a `.crt` file:

```
openssl x509 -in foo.pem -inform PEM -out foo.crt
```

Or a `.cer` file can be converted to a `.crt` file:

```
openssl x509 -inform DER -in foo.cer -out foo.crt
```

[

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answered Jan 12, 2012 at 12:37