Tuesday, August 3, 2010

Setting up an SSL secured Webserver with CentOS

1. Getting the required software

For an SSL encrypted web server you will need a few things. Depending on your install you may or may not have OpenSSL and mod_ssl, Apache's interface to OpenSSL. Use yum to get them if you need them.
yum install mod_ssl openssl
Yum will either tell you they are installed or will install them for you.

2. Generate a self-signed certificate

Using OpenSSL we will generate a self-signed certificate. If you are using this on a production server you are probably likely to want a key from Trusted Certificate Authority, but if you are just using this on a personal site or for testing purposes a self-signed certificate is fine. To create the key you will need to be root so you can either su to root or use sudo in front of the commands
# Generate private key 
openssl genrsa -out ca.key 1024 

# Generate CSR 
openssl req -new -key ca.key -out ca.csr

# Generate Self Signed Key
openssl x509 -req -days 365 -in ca.csr -signkey ca.key -out ca.crt

# Move the files to the correct locations
mv ca.crt /etc/pki/tls/certs
mv ca.key /etc/pki/tls/private/ca.key
mv ca.csr /etc/pki/tls/private/ca.csr
Then we need to update the Apache SSL configuration file
vi +/SSLCertificateFile /etc/httpd/conf.d/ssl.conf
Change the paths to match where the Key file is stored. If you've used the method above it will be
SSLCertificateFile /etc/pki/tls/certs/ca.crt
Then set the correct path for the Certificate Key File a few lines below. If you've followed the instructions above it is:
SSLCertificateKeyFile /etc/pki/tls/private/ca.key
Quit and save the file and then restart Apache
/etc/init.d/httpd restart
All being well you should now be able to connect over https to your server and see a default Centos page. As the certificate is self signed browsers will generally ask you whether you want to accept the certificate. Firefox 3 won't let you connect at all but you can override this.

Restart Apache again using
/etc/init.d/httpd restart

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