# Certificate Documentation This directory contains scripts to create the server certificates. To make a set of default (i.e. test) certificates, simply type: ``` $ ./bootstrap ``` The `openssl` command will be run against the sample configuration files included here, and will make a self-signed certificate authority (i.e. root CA), and a server certificate. This "root CA" should be installed on any client machine needing to do EAP-TLS, PEAP, or EAP-TTLS. The Extended Key Usage (EKU) fields for "TLS web server" will be automatically included in the server certificate. Without those extensions many clients will refuse to authenticate to FreeRADIUS. The root CA and the "XP Extensions" file also contain a crlDistributionPoints attribute. Many systems need this to be present in order to validate the RADIUS server certificate. The RADIUS server must have the URI defined but the CA need not have...however it is best practice for a CA to have a revocation URI. Note that whilst the Windows Mobile client cannot actually use the CRL when doing 802.1X it is recommended that the URI be an actual working URL and contain a revocation format file as there may be other OS behaviour at play and future OSes that may do something with that URI. For Windows, you will need to import the `p12` and/or the `der` format of the certificates. Linux systems need the `pem` format. In general, you should use self-signed certificates for 802.1X (EAP) authentication. When you list root CAs from other organisations in the `ca_file`, you permit them to masquerade as you, to authenticate your users, and to issue client certificates for EAP-TLS. If you already have CA and server certificates, rename (or delete) this directory, and create a new `certs` directory containing your certificates. Note that the `make install` command will **not** over-write your existing `raddb/certs` directory. ## New Installations of FreeRADIUS We suggest that new installations use the test certificates for initial tests, and then create real certificates to use for normal user authentication. See the instructions below for how to create the various certificates. The old test certificates can be deleted by running the following command: ``` $ make destroycerts ``` Then, follow the instructions below for creating real certificates. If you do not want to enable EAP-TLS, PEAP, or EAP-TTLS, then delete the relevant sub-sections from the `raddb/mods-available/eap` file. See the comments in that file for more information. ## Making a root Certificate We recommend using a private certificate authority (CA). While it can be difficult to install this CA on multiple client machines, it is (in general) more secure. ``` $ vi ca.cnf ``` Edit `default_days` to set the desired lifetime of the CA certificate. Edit the `input_password` and `output_password` fields to be the password for the CA certificate. Edit the `[certificate_authority]` section to have the correct values for your country, state, etc. Create the CA certificate: ``` $ make ca.pem ``` Then the `DER` format needed by Windows: ``` $ make ca.der ``` ## Making a Server Certificate The following steps will let you create a server certificate for use with TLS-based EAP methods, such as EAP-TLS, PEAP, and TTLS. Follow similar steps to create an `inner-server.pem` file, for use with EAP-TLS that is tunneled inside of another TLS-based EAP method. ``` $ vi server.cnf ``` Edit `default_days` to set the lifetime of the server certificate. The maximum for this is 825 for compatibility with all client devices. Edit the `input_password` and `output_password` fields to be the password for the server certificate. Edit the `[server]` section to have the correct values for your country, state, etc. Be sure that the `commonName` field here is different from the `commonName` for the CA certificate. Create the server certificate: ``` $ make server ``` ### Making a certificate for a public CA If you wish to use an existing certificate authority, you can create a certificate signing request for the server certificate, edit `server.cnf` as above, and run the following command. ``` $ make server.csr ``` This step creates a "Certificate Signing Request" suitable for submission to a public CA. ## Making a Client certificate Client certificates are used by EAP-TLS, and optionally by EAP-TTLS and PEAP. The following steps outline how to create a client certificate that is signed by the CA certificate created above. You will have to have the password for the CA certificate in the `input_password` and `output_password` fields of the `ca.cnf` file. ``` $ vi client.cnf ``` Edit `default_days` to set the lifetime of the client certificate. Edit the `input_password` and `output_password` fields to be the password for the client certificate. You will have to give these passwords to the end user who will be using the certificates. Edit the `[client]` section to have the correct values for your country, state, etc. Be sure that the `commonName` field here is the `User-Name` which will be used for logins! ``` $ make client ``` The users certificate will be in `emailAddress.pem`, e.g. `user@example.com.pem`. To create another client certificate, just repeat the steps for making a client certificate, being sure to enter a different login name for `commonName`, and a different password. ## Performance EAP performance for EAP-TLS, TTLS, and PEAP is dominated by SSL calculations. That is, a normal system can handle PAP authentication at a rate of 10k packets/s. However, SSL involves RSA calculations, which are very expensive. To benchmark your system, do: ``` $ openssl speed rsa ``` or ``` $ openssl speed rsa2048 ``` to test 2048 bit keys. The number that is printed is the **maximum** number of authentications per second which can be done for EAP-TLS (or TTLS, or PEAP). In practice, you will see results much lower than this number, i.e. the actual EAP-TLS performance may be half of the number printed here. The reason is that EAP requires many round-trip packets, whereas `openssl speed rsa2028` only does RSA calculations, and nothing else. ## Compatibility The certificates created using this method are known to be compatible with ALL operating systems. Some common issues are: * iOS and macOS have requirements on certificates. See: https://support.apple.com/en-us/HT210176 * Many systems require certain OIDs in the certificates (`id-kp-serverAuth` for `TLS Web server authentication`). If the certificate does not contain these fields, the system will stop doing EAP. The most visible effect is that the client starts EAP, gets a few Access-Challenge packets, and then a little while later re-starts EAP. If this happens, see the FAQ, and the comments in `raddb/mods-available/eap` for how to fix it. * All systems requires the root certificates to be on the client PC. If it doesn't have them, you will see the same issue as above. * Windows XP post SP2 has a bug where it has problems with certificate chains. i.e. if the server certificate is an intermediate one, and not a root one, then authentication will silently fail, as above. * Some versions of Windows CE cannot handle 4K RSA certificates. They will (again) silently fail, as above. * In none of these cases will Windows give the end user any reasonable error message describing what went wrong. This leads people to blame the RADIUS server. That blame is misplaced. * Certificate chains of more than 64K bytes are known to not work. This is partly a problem in FreeRADIUS. However, most clients cannot handle 64K certificate chains. Most Access Points will shut down the EAP session after about 50 round trips, while 64K certificate chains will take about 60 round trips. So don't use large certificate chains. They will only work after everyone upgrades everything in the network. * All other operating systems are known to work with EAP and FreeRADIUS. This includes Linux, the BSDs, macOS, iOS, Android, Solaris, Symbian, along with all known embedded systems, phones, WiFi devices, etc. ## Security Considerations The default certificate configuration files uses SHA256 for message digests for security.