From 4405c1ab276291c55839dde3001db5f8d8d538dd Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Sun, 16 Jun 2002 12:24:16 +0000 Subject: [PATCH] Added TLS configuration, mostly the same as the man pages but fleshed out a little more. --- doc/guide/admin/tls.sdf | 181 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 179 insertions(+), 2 deletions(-) diff --git a/doc/guide/admin/tls.sdf b/doc/guide/admin/tls.sdf index 924b252879..4e24eb4d99 100644 --- a/doc/guide/admin/tls.sdf +++ b/doc/guide/admin/tls.sdf @@ -8,6 +8,8 @@ OpenLDAP clients and servers are capable of using the integrity and confidentiality protections and to support LDAP authentication using the {{TERM:SASL}} EXTERNAL mechanism. +H2: TLS Certificates + TLS uses {{TERM:X.509}} certificates to carry client and server identities. All servers are required to have valid certificates, whereas client certificates are optional. Clients must have a @@ -15,7 +17,7 @@ valid certificate in order to authenticate via SASL EXTERNAL. For more information on creating and managing certificates, see the {{PRD:OpenSSL}} documentation. -H2: Server Certificates +H3: Server Certificates The DN of a server certificate must use the CN attribute to name the server, and the {{EX:CN}} must carry the server's @@ -23,7 +25,7 @@ fully qualified domain name. Additional alias names and wildcards may be present in the {{EX:subjectAltName}} certificate extension. More details on server certificate names are in {{REF:RFC2830}}. -H2: Client Certificates +H3: Client Certificates The DN of a client certificate can be used directly as an authentication DN. @@ -35,3 +37,178 @@ the DNs may not be exactly the same, and so the mapping facility described in {{SECT:Mapping Authentication identities to LDAP entries}} can be applied to these DNs as well. + +H2: TLS Configuration + +After obtaining the required certificates, a +number of options must be configured on both the client +and the server to enable TLS and make use of the certificates. +At a minimum, the clients must be configured with the filename +containing all of the {{TERM[expand]CA}} (CA) certificates it +will trust. The server must be configured with the {{TERM:CA}} +certificates and also its own server certificate and private key. + +Typically a single CA will have issued the server certificate +and all of the trusted client certificates, so the server only +needs to trust that one signing CA. However, a client may wish +to connect to a variety of secure servers managed by different +organizations, with server certificates generated by many +different CAs. As such, a client is likely to need a list of +many different trusted CAs in its configuration. + +H3: Server Configuration + +The configuration directives for slapd belong in the global directives +section of {{slapd.conf}}(5). + +H4: TLSCACertificateFile + +This directive specifies the {{TERM:PEM}}-format file containing +certificates for the CA's that slapd will trust. The certificate for +the CA that signed the server certificate must be included among +these certificates. If the signing CA was not a top-level (root) CA, +certificates for the entire sequence of CA's from the signing CA to +the top-level CA should be present. Multiple certificates are simply +appended to the file; the order is not significant. + +H4: TLSCACertificatePath + +This directive specifies the path of a directory that contains +individual {{TERM:CA}} certificates in separate files. In addition, +this directory must be specially managed using the OpenSSL {{c_rehash}} +utility. When using this feature, the OpenSSL library will attempt to +locate certificate files based on a hash of their name and serial number. +The {{c_rehash}} utility is used to generate symbolic links with the +hashed names that point to the actual certificate files. As such, +this option can only be used with a filesystem that actually supports +symbolic links. In general, it is simpler to use the +{{EX:TLSCACertificateFile}} directive instead. + +H4: TLSCertificateFile + +This directive specifies the file that contains the slapd server +certificate. Certificates are generally public information and +require no special protection. + +H4: TLSCertificateKeyFile + +This directive specifies the file that contains the private key +that matches the certificate stored in the {{EX:TLSCertificateFile}} +file. Private keys themselves are sensitive data and are usually +password encrypted for protection. However, the current implementation +doesn't support encrypted keys so the key must not be encrypted +and the file itself must be protected carefully. + +H4: TLSCipherSuite + +This directive configures what ciphers will be accepted and the +preference order. {{EX:}} should be a cipher +specification for OpenSSL. You can use the command + +> openssl ciphers -v ALL + +to obtain a verbose list of available cipher specifications. +Besides the individual cipher names, the specifiers {{EX:HIGH}}, +{{EX:MEDIUM}}, {{EX:LOW}}, {{EX:EXPORT}}, and {{EX:EXPORT40}} +may be helpful, along with {{EX:TLSv1}}, {{EX:SSLv3}}, +and {{EX:SSLv2}}. + +H4: TLSRandFile + +This directive specifies the file to obtain random bits from when +{{EX:/dev/urandom}} is not available. If the +system provides {{EX:/dev/urandom}} then this option is not needed, +otherwise a source of random data must be configured. +Some systems (e.g. Linux) +provide {{EX:/dev/urandom}} by default, while others (e.g. Solaris) +require the installation of a patch to provide it, and others may +not support it at all. In the latter case, EGD or PRNGD should be +installed, and this directive should specify the name of the EGD/PRNGD +socket. The environment variable {{EX:RANDFILE}} can also be used to specify +the filename. Also, in the absence of these options, the {{EX:.rnd}} +file in the slapd user's home directory may be used if it exists. To +use the {{EX:.rnd}} file, just create the file and copy a few hundred +bytes of arbitrary data into the file. The file is only used to +provide a seed for the pseudo-random number generator, and it doesn't +need very much data to work. + +H4: TLSVerifyClient { never | allow | try | demand } + +This directive specifies what checks to perform on client certificates +in an incoming TLS session, if any. This option is set to {{EX:never}} +by default, in which case the server never asks the client for a +certificate. With a setting of {{EX:allow}} the server will ask +for a client certificate; if none is provided the session proceeds +normally. If a certificate is provided but the server is unable to +verify it, the certificate is ignored and the session proceeds +normally, as if no certificate had been provided. With a setting of +{{EX:try}} the certificate is requested, and if none is provided, +the session proceeds normally. If a certificate is provided and it +cannot be verified, the session is immediately terminated. With a +setting of {{EX:demand}} the certificate is requested and a valid +certificate must be provided, otherwise the session is immediately +terminated. + +Note: The server must request a client certificate in order to +use the SASL EXTERNAL authentication mechanism with a TLS session. +As such, a non-default {{EX:TLSVerifyClient}} setting must be configured +before SASL EXTERNAL authentication may be attempted, and the +SASL EXTERNAL mechanism will only be offered to the client if a valid +client certificate was received. + +H3: Client Configuration + +Most of the client configuration directives parallel the server +directives. The names of the directives are different, and they go +into {{ldap.conf}}(5) instead of {{slapd.conf}}(5), but their +functionality is mostly the same. Also, while most of these options may +be configured on a system-wide basis, they may all be overridden by +individual users in their {{.ldaprc}} files. + +H4: TLS_CACERT + +This is equivalent to the server's {{EX:TLSCACertificateFile}} option. As +noted in the {{SECT:TLS Configuration}} section, a client typically +may need to know about more CAs than a server, but otherwise the +same considerations apply. + +H4: TLS_CACERTDIR + +This is equivalent to the server's {{EX:TLSCACertificatePath}} option. The +specified directory must be managed with the OpenSSL {{c_rehash}} +utility as well. + +H4: TLS_CERT + +This directive specifies the file that contains the client certificate. +This is a user-only directive and can only be specified in a user's +{{.ldaprc}} file. + +H4: TLS_KEY + +This directive specifies the file that contains the private key +that matches the certificate stored in the {{EX:TLS_CERT}} +file. The same constraints mentioned for {{EX:TLSCertificateKeyFile}} +apply here. This is also user-only directive. + +H4: TLS_RANDFILE + +This directive is the same as the server's {{EX:TLSRandFile}} +option. + +H4: TLS_REQCERT { never | allow | try | demand } + +This directive is equivalent to the server's {{EX:TLSVerifyClient}} +option. However, for clients the default value is {{EX:demand}} +and there generally is no good reason to change this setting. + +H4: TLS { never | hard } + +This directive specifies whether client connections should use TLS +by default. The default setting is {{EX:never}} which specifies that +connections will be opened in the clear unless TLS is explicitly +specified using an "ldaps://" URL. When set to {{EX:hard}} all +connections will be established with TLS, as if an "ldaps://" URL +was specified. Note that the use of ldaps is a holdover from LDAPv2 +and this setting is incompatible with the LDAPv3 StartTLS request. +As such, it's best not to use this option. -- 2.39.5