Securely transfer files between two hosts using HTTPS in Linux


Written by - Deepak Prasad

How to configure apache http server to transfer files? Steps to configure apache HTTP server over TLS/SSL to transfer files. How to configure Apache server using TLS/SSL to upload and transfer file using curl. How to transfer files over https? How to upload file using curl to an HTTPS server. How to configure HTTP server using LIMIT to allow download and upload of a file or directory using curl in Linux.

Securely transfer files between two hosts using HTTPS in Linux

Earlier I had written an article with 5 different commands to securely transfer files between multiple hosts. Now you can consider HTTPS also as one of the possible options to securely transfer files (upload and download) between multiple hosts over the network.

In this article I will share the steps to configure an apache HTTP server using TLS/SSL and then transfer file to HTTPS server using curl (uploading a file). I am using CentOS 7.4 to demonstrate the steps from this article. I will configure a very basic HTTP server with not much customization as Apache can be very complex if we enter into using all the features. But since we are concentrating on configuring an HTTPS server to upload and download a file (transfer a file), we will configure a basic HTTPS server.

 

Install Apache

The very first thing we have to do is install the apache rpm before we start configuring our web server.

[root@node2 ~]# yum -y install httpd

Next we will create some dummy file and directory and publish it on our webserver.

[root@node2 ~]# cd /var/www/html/
[root@node2 html]# mkdir secret
[root@node2 html]# chmod 777 secret

I am creating an alias /web which will redirect to /var/www/html/secret. Also we have defined directive. The directive limits the scope of the enclosed directives by URL. It is similar to the directive, and starts a subsection which is terminated with a directive. sections are processed in the order they appear in the configuration file, after the sections and .htaccess files are read, and after the sections.

The purpose of the directive is to restrict the effect of the access controls to the nominated HTTP methods. For all other methods, the access restrictions that are enclosed in the bracket will have no effect.

[root@node2 ~]# vim /etc/httpd/conf/httpd.conf
Alias /web "/var/www/html/secret"
  <Directory "/var/www/html/secret">
      Options Indexes MultiViews FollowSymLinks Includes ExecCGI
      AllowOverride None
      Allow from all
      Require all granted
  </Directory>

  <Location /web>
     Dav On
     <LimitExcept GET HEAD OPTIONS PUT>
        Order Allow,Deny
        Allow from all
     </LimitExcept>
  </Location>

Next restart the httpd services to make the changes affect.

[root@node2 ~]# systemctl restart httpd

Check the service status.

[root@node2 ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: active (running) since Sun 2019-04-14 13:52:04 IST; 9min ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 3134 (httpd)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"
    Tasks: 6
   CGroup: /system.slice/httpd.service
           ├─3134 /usr/sbin/httpd -DFOREGROUND
           ├─3255 /usr/sbin/httpd -DFOREGROUND
           ├─3256 /usr/sbin/httpd -DFOREGROUND
           ├─3257 /usr/sbin/httpd -DFOREGROUND
           ├─3259 /usr/sbin/httpd -DFOREGROUND
           └─3260 /usr/sbin/httpd -DFOREGROUND

Apr 14 13:52:04 node2.example.com systemd[1]: Starting The Apache HTTP Server...
Apr 14 13:52:04 node2.example.com systemd[1]: Started The Apache HTTP Server.

Enable the httpd service to make it reboot persistent.

[root@node2 ~]# systemctl enable httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.

 

Create TLS/SSL certificates

We will store all our key and certificates inside "/etc/pki/tls/certs/"

Let us start by creating 2048 bit SSL key

[root@node2 html]# cd /etc/pki/tls/certs/
[root@node2 certs]# openssl genpkey -algorithm rsa -pkeyopt rsa_keygen_bits:2048 -out node2.example.com.key
........+++
.....................................................+++

Verify the created key "node2.example.com.key"

[root@node2 certs]# ls -ltr
total 16
-rwxr-xr-x. 1 root root  829 Oct 31 04:12 renew-dummy-cert
-rw-r--r--. 1 root root 2516 Oct 31 04:12 Makefile
-rwxr-xr-x. 1 root root  610 Oct 31 04:12 make-dummy-cert
lrwxrwxrwx. 1 root root   55 Feb 17 17:28 ca-bundle.trust.crt -> /etc/pki/ca-trust/extracted/openssl/ca-bundle.trust.crt
lrwxrwxrwx. 1 root root   49 Feb 17 17:28 ca-bundle.crt -> /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem
-rw-r--r--. 1 root root 1704 Apr 14 11:26 node2.example.com.key

Once the key is generated, next generate a Certificate Request (CSR). You can encrypt the key using a passphrase which will be prompted at the end.

[root@node2 certs]# openssl req -new -key node2.example.com.key -out node2.example.com.csr
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:IN
State or Province Name (full name) []:KARNATAKA
Locality Name (eg, city) [Default City]:BANGALORE
Organization Name (eg, company) [Default Company Ltd]:GoLinuxCloud
Organizational Unit Name (eg, section) []:TEST
Common Name (eg, your name or your server's hostname) []:node2.example.com
Email Address []:golinuxcloud@gmail.com

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Verify the CSR file

[root@node2 certs]# ls -ltr
total 20
-rwxr-xr-x. 1 root root  829 Oct 31 04:12 renew-dummy-cert
-rw-r--r--. 1 root root 2516 Oct 31 04:12 Makefile
-rwxr-xr-x. 1 root root  610 Oct 31 04:12 make-dummy-cert
lrwxrwxrwx. 1 root root   55 Feb 17 17:28 ca-bundle.trust.crt -> /etc/pki/ca-trust/extracted/openssl/ca-bundle.trust.crt
lrwxrwxrwx. 1 root root   49 Feb 17 17:28 ca-bundle.crt -> /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem
-rw-r--r--. 1 root root 1704 Apr 14 11:26 node2.example.com.key
-rw-r--r--. 1 root root 1078 Apr 14 11:28 node2.example.com.csr

Lastly sign the certificate and create a CRT file

[root@node2 certs]# openssl x509 -req -days 365 -signkey node2.example.com.key -in node2.example.com.csr -out node2.exam                                                                                                                     ple.com.crt
Signature ok
subject=/C=IN/ST=KARNATAKA/L=BANGALORE/O=GoLinuxCloud/OU=TEST/CN=node2.example.com/emailAddress=golinuxcloud@gmail.com
Getting Private key

Verify the CRT file

[root@node2 certs]# ls -ltr
total 24
-rwxr-xr-x. 1 root root  829 Oct 31 04:12 renew-dummy-cert
-rw-r--r--. 1 root root 2516 Oct 31 04:12 Makefile
-rwxr-xr-x. 1 root root  610 Oct 31 04:12 make-dummy-cert
lrwxrwxrwx. 1 root root   55 Feb 17 17:28 ca-bundle.trust.crt -> /etc/pki/ca-trust/extracted/openssl/ca-bundle.trust.crt
lrwxrwxrwx. 1 root root   49 Feb 17 17:28 ca-bundle.crt -> /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem
-rw-r--r--. 1 root root 1704 Apr 14 11:26 node2.example.com.key
-rw-r--r--. 1 root root 1078 Apr 14 11:28 node2.example.com.csr
-rw-r--r--. 1 root root 1354 Apr 14 11:29 node2.example.com.crt

So now we have all the keys what we need to configure our apache server with SSL.

 

Module Management (mod_ssl)

The Apache web server includes many modular features. For example, it’s not possible to set up SSL-secured websites without the mod_ssl package, which includes the mod_ssl.so module along with the ssl.conf configuration file.

A number of other similar systems are organised in modules. Loaded modules are included in standard Apache configuration files with the LoadModule directive. A full list of available modules is located in the /usr/lib64/httpd/modules directory, but available modules aren’t used unless they’re loaded with the LoadModule directive in appropriate Apache configuration files within the /etc/httpd/conf.modules.d directory.

So we will install mod_ssl using 'yum' command

[root@node2 certs]# yum install openssl mod_ssl -y

 

Configure SSL

Next we will configure our apache with SSL keys . Add the below content at the end of "/etc/httpd/conf.d/ssl.conf" file.

[root@node2 ~]# vim /etc/httpd/conf.d/ssl.conf
<VirtualHost *:443>
        DocumentRoot "/var/www/html"
        ServerName node2.example.com:443
        SSLCertificateFile /etc/pki/tls/certs/node2.example.com.crt
        SSLCertificateKeyFile   /etc/pki/tls/certs/node2.example.com.key
</VirtualHost>

Restart the httpd service

[root@node2 ~]# systemctl restart httpd

Next verify your web server. Connect to node2.example.com using https.

Securely transfer files between two hosts using HTTPS in Linux

Securely transfer files between two hosts using HTTPS in Linux

Securely transfer files between two hosts using HTTPS in Linux

Below is the certificate which we have generated

Securely transfer files between two hosts using HTTPS in Linux

Securely transfer files between two hosts using HTTPS in Linux

Securely transfer files between two hosts using HTTPS in Linux

Securely transfer files between two hosts using HTTPS in Linux

So our apache server is properly configured with SSL.

 

Disable SELinux

For the sake of this article we have disabled SELinux policy.

Change SELINUX in /etc/selinux/config to Disabled as shown below

SELINUX=disabled

and reboot the node.

Once the node comes up, check the selinux status

[root@node2 ~]# getenforce
Disabled

 

Transfer files using curl on HTTPS

Next we come to the main topic of this article. We will create a dummy file which we will attempt to upload to our HTTPS server using curl.

[root@node2 ~]# touch /tmp/secret_file

Using the below command we are uploading /tmp/secret_file to the provided web server location

NOTE:
Since we do not have a certified CA, we are using --insecure argument here.
[root@node2 ~]# curl --insecure  -T /tmp/secret_file https://node2.example.com/web/
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>201 Created</title>
</head><body>
<h1>Created</h1>
<p>Resource /web/secret_file has been created.</p>
</body></html>
[root@node2 ~]# ls -l /var/www/html/secret/
total 0
-rw-r--r-- 1 apache apache 0 Apr 14 14:03 secret_file

Securely transfer files between two hosts using HTTPS in Linux

 

You can also upload a file using a certain user for enhanced security. To use a user, your apache must be configured to allow access for specific user. I have written another article with the steps to authenticate user to use apache server. Once you have the user in place, try the below command and replace root:redhat with user:password. Here we are uploading root_file available under /tmp location to our web server.

[root@node2 ~]# touch /tmp/root_file
[root@node2 ~]# curl --insecure -u root:redhat -T /tmp/root_file https://node2.example.com:443/web/
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>201 Created</title>
</head><body>
<h1>Created</h1>
<p>Resource /web/root_file has been created.</p>
</body></html>
[root@node2 ~]# ls -l /var/www/html/secret/
total 0
-rw-r--r-- 1 apache apache 0 Apr 14 14:04 root_file
-rw-r--r-- 1 apache apache 0 Apr 14 14:04 secret_file

 

Lastly I hope the steps from the article to configure HTTPS server to transfer files on Linux was helpful. So, let me know your suggestions and feedback using the comment section.

 

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Deepak Prasad

He is the founder of GoLinuxCloud and brings over a decade of expertise in Linux, Python, Go, Laravel, DevOps, Kubernetes, Git, Shell scripting, OpenShift, AWS, Networking, and Security. With extensive experience, he excels in various domains, from development to DevOps, Networking, and Security, ensuring robust and efficient solutions for diverse projects. You can reach out to him on his LinkedIn profile or join on Facebook page.

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