Apache ssl tools

The file may be called httpd. To have your site accessible via secure and non-secure connection, you will need two separate configuration files: one for port 80 and the other for port We recommend you backup the configuration file before making any changes to it.

This way you can revert the changes if something goes wrong. Note: starting from Apache 2. OCSP Stapling improves performance by providing the clients with up-to-date status of your certificate. If the syntax is OK, save your changes in the configuration file and restart Apache using these apachectl commands:. This path is relative to ServerRoot.

For example:. You can use the openssl command-line program to verify that an OCSP response is sent by your server:.

The following sections highlight the most common situations which require further modification to the configuration. With more than a few certificates, the stapling cache size bytes in the example above may need to be increased.

Error message AH will be logged in case of an error storing a response. You can confirm that a server certificate points to an OCSP responder using the openssl command-line program, as follows:. Note that firewall rules that control outbound connections from the web server may need to be adjusted. Several directives are available to handle timeouts and errors. In order to support OCSP Stapling when a particular server certificate is used, the certificate chain for that certificate must be configured.

If it was not configured as part of enabling SSL, the AH error will be issued when stapling is enabled, and an OCSP response will not be provided for clients using the certificate.

When you know all of your users eg, as is often the case on a corporate Intranet , you can require plain certificate authentication. All you need to do is to create client certificates signed by your own CA certificate ca. The key to doing this is checking that part of the client certificate matches what you expect.

Although Alice may encrypt her message to make it private, there is still a concern that someone might modify her original message or substitute it with a different one, in order to transfer the money to themselves, for instance.

One way of guaranteeing the integrity of Alice's message is for her to create a concise summary of her message and send this to the bank as well. Upon receipt of the message, the bank creates its own summary and compares it with the one Alice sent. If the summaries are the same then the message has been received intact. A summary such as this is called a message digest , one-way function or hash function.

Message digests are used to create a short, fixed-length representation of a longer, variable-length message. Digest algorithms are designed to produce a unique digest for each message.

Message digests are designed to make it impractically difficult to determine the message from the digest and in theory impossible to find two different messages which create the same digest -- thus eliminating the possibility of substituting one message for another while maintaining the same digest. Another challenge that Alice faces is finding a way to send the digest to the bank securely; if the digest is not sent securely, its integrity may be compromised and with it the possibility for the bank to determine the integrity of the original message.

Only if the digest is sent securely can the integrity of the associated message be determined. When Alice sends a message to the bank, the bank needs to ensure that the message is really from her, so an intruder cannot request a transaction involving her account.

A digital signature , created by Alice and included with the message, serves this purpose. Digital signatures are created by encrypting a digest of the message and other information such as a sequence number with the sender's private key. Though anyone can decrypt the signature using the public key, only the sender knows the private key.

This means that only the sender can have signed the message. Including the digest in the signature means the signature is only good for that message; it also ensures the integrity of the message since no one can change the digest and still sign it. To guard against interception and reuse of the signature by an intruder at a later date, the signature contains a unique sequence number.

This protects the bank from a fraudulent claim from Alice that she did not send the message -- only she could have signed it non-repudiation.

Although Alice could have sent a private message to the bank, signed it and ensured the integrity of the message, she still needs to be sure that she is really communicating with the bank. This means that she needs to be sure that the public key she is using is part of the bank's key-pair, and not an intruder's.

Similarly, the bank needs to verify that the message signature really was signed by the private key that belongs to Alice. If each party has a certificate which validates the other's identity, confirms the public key and is signed by a trusted agency, then both can be assured that they are communicating with whom they think they are. Such a trusted agency is called a Certificate Authority and certificates are used for authentication. A certificate associates a public key with the real identity of an individual, server, or other entity, known as the subject.

As shown in Table 1 , information about the subject includes identifying information the distinguished name and the public key. It also includes the identification and signature of the Certificate Authority that issued the certificate and the period of time during which the certificate is valid. It may have additional information or extensions as well as administrative information for the Certificate Authority's use, such as a serial number.

A distinguished name is used to provide an identity in a specific context -- for instance, an individual might have a personal certificate as well as one for their identity as an employee. Distinguished names are defined by the X. A Certificate Authority may define a policy specifying which distinguished field names are optional and which are required.

It may also place requirements upon the field contents, as may users of certificates. The binary format of a certificate is defined using the ASN. This notation defines how to specify the contents and encoding rules define how this information is translated into binary form. When placed between begin and end delimiter lines as below , this encoded version is called a PEM "Privacy Enhanced Mail" encoded certificate.

By verifying the information in a certificate request before granting the certificate, the Certificate Authority assures itself of the identity of the private key owner of a key-pair. For instance, if Alice requests a personal certificate, the Certificate Authority must first make sure that Alice really is the person the certificate request claims she is.

A Certificate Authority may also issue a certificate for another Certificate Authority. When examining a certificate, Alice may need to examine the certificate of the issuer, for each parent Certificate Authority, until reaching one which she has confidence in. She may decide to trust only certificates with a limited chain of issuers, to reduce her risk of a "bad" certificate in the chain.

As noted earlier, each certificate requires an issuer to assert the validity of the identity of the certificate subject, up to the top-level Certificate Authority CA. This presents a problem: who can vouch for the certificate of the top-level authority, which has no issuer?

In this unique case, the certificate is "self-signed", so the issuer of the certificate is the same as the subject. Browsers are preconfigured to trust well-known certificate authorities, but it is important to exercise extra care in trusting a self-signed certificate.