|Superslave|No|
|Autoserial|No|
|DNSSEC|No|
+
+
+
+
+# Introduction
+
+TITLE: INTRODUCTION
+
+\_\_TOC\_\_
+
+Rationale
+---------
+
+This HOWTO documents the steps necessary to build and use the LDAP DNS
+backend I've written for PowerDNS, an extremely versatile name server.
+This backend enables PowerDNS to retrieve DNS information from any
+standard compliant LDAP server. This is extremely handy if you have
+already stored information about your hosts in your LDAP tree.
+
+Download
+--------
+
+The LDAP DNS backend is included in the PowerDNS source tree. You can
+get the latest packages of PowerDNS by visiting
+[PowerDNS.com](http://www.powerdns.com) or
+<http://download.powerdns.com>.
+
+Credits
+-------
+
+I would like to thank Bert Hubert for his courage to write a clean
+implementation of the DNS protocol, which is a real nightmare for every
+good programmer. You will understand what I mean, if you read the specs
+yourself
+
+As a result PowerDNS is an extremely versatile DNS server consisting of
+very good source code which is easy to understand and to extend. Please
+support him by contributing code or bug reports or spread the word of
+PowerDNS ;-)
+
+TITLE: DOWNLOAD
+
+The PowerDNS LDAP backend is part of the PowerDNS distribution which is
+available at [PowerDNS.com](http://www.powerdns.com/en/downloads.aspx)
+
+Resources
+---------
+
+**Note:** As of 2008-03-24 the schema contains many new record types
+which are backed by the IANA list of DNS record types.
+
+[dnsdomain2.schema](http://www.linuxnetworks.de/pdnsldap/dnsdomain2.schema)
+
+The LDAP dnsdomain2 schema contains the additional object descriptions
+which are required by the LDAP server to check the validity of entries
+when they are added. Please consult the documentation of your LDAP
+server to find out how to add this schema to the server.
+
+Patches
+-------
+
+None at the moment
+
+TITLE: INSTALLATION
+
+\_\_TOC\_\_
+
+Compilation
+-----------
+
+Before performing the steps to compile the PowerDNS server and the LDAP
+DNS backend you have to install a LDAP development package, which
+includes all necessary headers. The openldap-devel package is provided
+by most distributions. Apply these steps to the source .tar.gz file, if
+you don't want to use a pre-compiled package:
+
+`* Extract the tar file`\
+`* Change into the newly created pdns directory`\
+`* Type ./configure --help for the available options`\
+`* For dynamic modules:`\
+` ./configure`\
+` --with-modules=""`\
+` --with-dynmodules="ldap"`\
+` --enable-recursor`\
+`* For a static binary:`\
+` ./configure`\
+` --with-modules="ldap"`\
+` --with-dynmodules=""`\
+` --enable-recursor`\
+`* make && make install`
+
+Configuration options
+---------------------
+
+There are a few options through the LDAP DNS backend can be configured
+for your environment. Add them to the pdns.conf file located in
+/etc/powerdns or /usr/local/etc/ (depends on your configuration while
+compiling):
+
+launch=ldap
+
+You'll have to add the LDAP DNS backend to the PowerDNS backends first
+by altering the launch declaration in the pdns.conf file. Otherwise the
+options below won't have any effect.
+
+ldap-host (default "ldap://127.0.0.1:389/") : The values assigned to this parameter can be LDAP URIs (e.g. <ldap://127.0.0.1/> or <ldaps://127.0.0.1/>) describing the connection to the LDAP server. There can be multiple LDAP URIs specified for load balancing and high availability if they are separated by spaces. In case the used LDAP client library doesn't support LDAP URIs as connection parameter, use plain host names or IP addresses instead (both may optionally be followed by a colon and the port).
+
+<!-- -->
+
+ldap-starttls (default "no") : Use TLS encrypted connections to the LDAP server. This is only allowed if ldap-host is a <ldap://> URI or a host name / IP address.
+
+<!-- -->
+
+ldap-basedn (default "") : The PowerDNS LDAP DNS backend searches below this path for objects containing the specified DNS information. The retrieval of attributes is limited to this subtree. This option must be set to the path according to the layout of your LDAP tree, e.g. ou=hosts,o=linuxnetworks,c=de is the DN to my objects containing the DNS information.
+
+<!-- -->
+
+ldap-binddn (default "") : Path to the object to authenticate against. Should only be used, if the LDAP server doesn't support anonymous binds.
+
+<!-- -->
+
+ldap-secret (default "") : Password for authentication against the object specified by ldap-binddn
+
+<!-- -->
+
+ldap-method (default "simple") :
+
+- simple
+
+: Search the requested domain by comparing the associatedDomain
+ attributes with the domain string in the question.
+
+- tree
+
+: Search entires by translating the domain string into a LDAP dn. Your
+ LDAP tree must be designed in the same way as your DNS LDAP tree.
+ The question for "myhost.linuxnetworks.de" would translate into
+ "dc=myhost,dc=linuxnetworks,dc=de,ou=hosts=..." and the entry where
+ this dn points to would be evaluated for dns records.
+
+- strict
+
+: Like simple, but generates PTR records from aRecords or aAAARecords.
+ Using "strict", you won't be able to do zone transfers for
+ reverse zones.
+
+<!-- -->
+
+ldap-filter-axfr (default "(:target:)" ) : LDAP filter for limiting AXFR results (zone transfers), e.g. (&(:target:)(active=yes)) for returning only entries whose attribute "active" is set to "yes".
+
+<!-- -->
+
+ldap-filter-lookup (default "(:target:)" ) : LDAP filter for limiting IP or name lookups, e.g. (&(:target:)(active=yes)) for returning only entries whose attribute "active" is set to "yes".
+
+TITLE: EXAMPLE
+
+\_\_TOC\_\_
+
+Tree design
+-----------
+
+The DNS LDAP tree should be designed carefully to prevent mistakes,
+which are hard to correct afterwards. The best solution is to create a
+subtree for all host entries which will contain the DNS records. You can
+do this the simple way or in a tree style.
+
+DN of a simple style example record (e.g. myhost.linuxnetworks.de):
+
+`dn: dc=myhost,dc=linuxnetworks,ou=hosts,...`
+
+DN of a tree style example record (e.g. myhost.test.linuxnetworks.de):
+
+`dn: dc=myhost,dc=test,dc=linuxnetworks,dc=de,ou=hosts,...`
+
+Basic objects
+-------------
+
+Each domain (or zone for BIND users) must include one object containing
+a SOA (Start Of Authority) record. This object can also contain the
+attribute for a MX (Mail eXchange) and a NS (Name Server) record. These
+attributes allow one or more values, e.g. for a backup mail or name
+server:
+
+`dn: dc=linuxnetworks,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dcobject`\
+`objectclass: dnsdomain`\
+`objectclass: domainrelatedobject`\
+`dc: linuxnetworks`\
+`soarecord: ns.linuxnetworks.de me@linuxnetworks.de 1 1800 3600 86400 7200`\
+`nsrecord: ns.linuxnetworks.de`\
+`mxrecord: 10 mail.linuxnetworks.de`\
+`mxrecord: 20 mail2.linuxnetworks.de`\
+`associateddomain: linuxnetworks.de `
+
+A simple mapping between name and IP address can be specified by an
+object containing an arecord and an associateddomain. You don't have to
+bother about a reverse mapping (ip address to name) if you don't want
+to, because this can be done automagically by the LDAP DNS backend if
+you set ldap-method=strict in pdns.conf.
+
+`dn: dc=server,dc=linuxnetworks,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain`\
+`objectclass: domainrelatedobject`\
+`dc: server`\
+`arecord: 10.1.0.1`\
+`arecord: 192.168.0.1`\
+`associateddomain: server.linuxnetworks.de`
+
+Be aware of the fact that these examples work if ldap-method is simple
+or strict. For tree mode you have to modify all DNs according to the
+algorithm described in the section above.
+
+Wildcards
+---------
+
+Wild-card domains are possible by using the asterisk in the
+associatedDomain value like it is used in the bind zone files. The "dc"
+attribute can be set to any value in simple or strict mode - this
+doesn't matter.
+
+`dn: dc=any,dc=linuxnetworks,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain`\
+`objectclass: domainrelatedobject`\
+`dc: any`\
+`arecord: 192.168.0.1`\
+`associateddomain: *.linuxnetworks.de`
+
+In tree mode wild-card entries has to look like this instead:
+
+`dn: dc=*,dc=linuxnetworks,dc=de,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain`\
+`objectclass: domainrelatedobject`\
+`dc: *`\
+`arecord: 192.168.0.1`\
+`associateddomain: *.linuxnetworks.de`
+
+Aliases
+-------
+
+Aliases for an existing DNS object have to be defined in a separate LDAP
+object. You can create one object per alias (this is a must in tree
+mode) or add all aliases (as values of associateddomain) to one object.
+The only thing which is not allowed is to create loops by using the same
+name in associateddomain and in cnamerecord
+
+`dn: dc=server-aliases,dc=linuxnetworks,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain`\
+`objectclass: domainrelatedobject`\
+`dc: server-aliases`\
+`cnamerecord: server.linuxnetworks.de`\
+`associateddomain: proxy.linuxnetworks.de`\
+`associateddomain: mail2.linuxnetworks.de`\
+`associateddomain: ns.linuxnetworks.de `
+
+Aliases are optional. You can also add all alias domains to the
+associateddomain attribute. The only difference is that these additional
+domains aren't recognized as aliases anymore, but instead as a normal
+arecord:
+
+`dn: dc=server,dc=linuxnetworks,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain`\
+`objectclass: domainrelatedobject`\
+`dc: server`\
+`arecord: 10.1.0.1`\
+`associateddomain: server.linuxnetworks.de`\
+`associateddomain: proxy.linuxnetworks.de`\
+`associateddomain: mail2.linuxnetworks.de`\
+`associateddomain: ns.linuxnetworks.de`
+
+Reverse lookups
+---------------
+
+Currently you have two options: Either reverse lookups handled by the
+code automagically or you have to add PTR records to your LDAP
+directory. If you want to derive PTR records from A records, you have
+set "ldap-method" to "strict". Otherwise add objects like below to your
+directory:
+
+`dn: dc=1.10.in-addr.arpa,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain2`\
+`objectclass: domainrelatedobject`\
+`dc: 1.10.in-addr.arpa`\
+`soarecord: ns.linuxnetworks.de me@linuxnetworks.de 1 1800 3600 86400 7200`\
+`nsrecord: ns.linuxnetworks.de`\
+`associateddomain: 1.10.in-addr.arpa `
+
+`dn: dc=1.0,dc=1.10.in-addr.arpa,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain2`\
+`objectclass: domainrelatedobject`\
+`dc: 1.0`\
+`ptrrecord: server.linuxnetworks.de`\
+`associateddomain: 1.0.1.10.in-addr.arpa `
+
+Tree mode requires each component to be a dc element of its own:
+
+`dn: dc=1,dc=0,dc=1,dc=10,dc=in-addr,dc=arpa,ou=hosts,o=linuxnetworks,c=de`\
+`objectclass: top`\
+`objectclass: dnsdomain2`\
+`objectclass: domainrelatedobject`\
+`dc: 1`\
+`ptrrecord: server.linuxnetworks.de`\
+`associateddomain: 1.0.1.10.in-addr.arpa `
+
+To use this kind of record, you also have to add the dnsdomain2 schema
+to the configuration of your LDAP server.
+
+**CAUTION:**
+
+You can't use "ldap-method=strict" if you need zone transfers (AXFR) to
+other name servers. Distributing zones can only be done directly via
+LDAP replication in this case, because for a full zone transfer the
+reverse records are missing
+
+TITLE: MIGRATION
+
+\_\_TOC\_\_
+
+BIND zone files
+---------------
+
+There is a small utility in the PowerDNS distribution available called
+"zone2ldap", which can convert zone files used by BIND to the ldif
+format. Ldif is a text file format containing information about LDAP
+objects and can be read by every standard compliant LDAP server.
+Zone2ldap needs the BIND named.conf (usually located in /etc) as input
+and writes the dns record entries in ldif format to stdout:
+
+Usage:
+
+`zone2ldap`\
+` --basedn=`<your-basedn>\
+` --named-conf=`<file>\
+` --resume`\
+` > zones.ldif`
+
+Alternatively zone2ldap can be used to convert only single zone files
+instead all zones:
+
+Usage:
+
+`zone2ldap`\
+` --basedn=`<your-basedn>\
+` --zone-file=`<file>\
+` --zone-name=`<file>\
+` --resume`\
+` > zone.ldif`
+
+Here is a complete list of all options:
+
+--help : Provides a short description of all options
+
+<!-- -->
+
+--basedn=... : Node below the new objects should be created. All nodes mentioned in the basedn must exist before you can add the ldif file to your LDAP DNS tree
+
+<!-- -->
+
+--layout=... : How the entries will be arranged in the LDAP directory. Currently "tree" (e.g. dc=host,dc=subdomain,dc=linuxnetworks,dc=de) and "list" (e.g. dc=host,dc=subdomain.linuxnetworks.de) are supported.
+
+<!-- -->
+
+--named-conf=... : Location of the BIND named.conf file
+
+<!-- -->
+
+--resume : Resume processing the zone files if an error occurs. An error message is written to stderr in this case and one or more objects may be missing but the rest of the zones are converted to ldif format
+
+<!-- -->
+
+--verbose : Outputs additional information about the operations to stderr
+
+<!-- -->
+
+--zone-file=... : Instead of a complete named.conf file you can also parse only a single zone file. If you pass a single dash ("-") as parameter, input is read from stdin.
+
+<!-- -->
+
+--zone-name=... : Name of the zone like it is mentioned in the named.conf or in the zone file, e.g. linuxnetworks.de. Necessary if you only want to parse single zone files
+
+Bind LDAP backend
+-----------------
+
+If you are using the [Bind LDAP sdb
+backend](http://bind9-ldap.bayour.com/), you can keep the records in the
+LDAP tree also for the PowerDNS LDAP backend. The schemas both backends
+utilize is almost the same exept for one important thing: Domains for
+PowerDNS are stored in the attibute "associatedDomain" whereas Bind
+stores them split in "relativeDomainName" and "zoneName".
+
+There is a [migration
+script](http://www.linuxnetworks.de/pdnsldap/bind2pdns-ldap) which
+creates a file in LDIF format with the necessary LDAP updates including
+the "associatedDomain" and "dc" attributes. The utility is executed on
+the command line by:
+
+`./bind2pdns-ldap`\
+` --host=`<host name or IP>\
+` --basedn=`<subtree dn>\
+` --binddn=`<admin dn>\
+` > update.ldif`
+
+The parameter "host" and "basedn" are mandatory, "binddn" is optional.
+If "binddn" is given, you will be asked for a password, otherwise an
+anonymous bind is executed. The updates in LDIF format are written to
+stdout and can be redirected to a file.
+
+The script requires Perl and the Perl Net::LDAP module and can be
+downloaded from
+[/pdnsldap/bind2pdns-ldap](http://www.linuxnetworks.de/pdnsldap/bind2pdns-ldap).
+
+Updating the entries in the LDAP tree requires to make the dnsdomain2
+schema known to the LDAP server. Unfortunately, both schemas (dnsdomain2
+and dnszone) share the same record types and use the same OIDs so the
+LDAP server can't use both schemas at the same time. The solution is to
+add the [dnsdomain2
+schema](http://www.linuxnetworks.de/pdnsldap/dnsdomain2.schema) and
+replace the dnszone schema by the [dnszone-migrate
+schema](http://www.linuxnetworks.de/pdnsldap/dnszone-migrate.schema).
+After restarting the LDAP server you can use attributes from both
+schemas and updating the objects in the LDAP tree using the LDIF file
+generated from bind2pdns-ldap will work without errors.
+
+Other name server
+-----------------
+
+The easiest way for migrating DNS records is to use the output of a zone
+transfer (AXFR). Save the output of the "dig" program provided by bind
+into a file and call zone2ldap with the file name as option to the
+--zone-file parameter. This will generate you an appropriate ldif file,
+which you can import into your LDAP tree. The bash script except below
+automates this for you.
+
+`DNSSERVER=127.0.0.1`\
+`DOMAINS="linuxnetworks.de 10.10.in-addr.arpa"`
+
+`for DOMAIN in $DOMAINS; do`\
+` dig @$DNSSERVER $DOMAIN AXFR> $DOMAIN.zone;`\
+` zone2ldap --zone-name=$DOMAIN --zone-file=$DOMAIN.zone> $DOMAIN.ldif;`\
+`done`
+
+TITLE: OPTIMIZATION
+
+\_\_TOC\_\_
+
+LDAP indices
+------------
+
+To improve performance, you can tell the LDAP server to maintain indices
+on certain attributes. This leads to much faster searches for these type
+of attributes.
+
+The LDAP DNS backend mainly searches for values in associatedDomain, so
+maintaining an index (pres,eq,sub) on this attribute is a big
+performance improvement:
+
+`index associatedDomain pres,eq,sub`
+
+Furthermore if you set ldap-method=strict, it uses the aRecord and
+aAAARecord attribute for reverse mapping of IP addresses to names. To
+maintain an index (pres,eq) on these attributes also improves
+performance of the LDAP server:
+
+`index aAAARecord pres,eq`\
+`index aRecord pres,eq`
+
+All other attributes than associatedDomain, aRecord or aAAARecord are
+only read if the object matches the specified criteria. Thus,
+maintaining an index on these attributes is useless.
+
+If you've inserted your entries before adding these statements to your
+slapd.conf, you have to stop your LDAP server and call slapindex on the
+command line. This will generate the indices for already existing
+attributes
+
+dNSTTL attribute
+----------------
+
+Converting the string in the dNSTTL attribute to an integer is a time
+consuming task. If you don't use a separate TTL value for each entry and
+use the default-ttl parameter in pdns.conf instead, you will gain a
+approx. 7% better performance for entries that aren't cached. You can
+still add a dNSTTL attribute to entries that should have a different TTL
+than the default TTL
+
+Access method
+-------------
+
+The method of accessing the entries in the directory affects the
+performance too. By default, the "simple" method is used search for
+entries by using their associatedDomain attribute. Alternatively you can
+choose the "tree" method, whereby the search is done along the directory
+tree, e.g. "host.example.dom" is translated into
+"dc=host,dc=example,dc=dom,...". This requires your LDAP DNS subtree
+layout to be 1:1 to the DNS tree, but then you will gain additional 7%
+better performance values
+
+TITLE: TROUBLESHOOTING
+
+\_\_TOC\_\_
+
+Trying to set unexisting parameter
+----------------------------------
+
+If your PowerDNS config file contains an unknown parameter or at least
+one of your parameters is not in the form
+
+`ldap-`*`name`*`=`*`value`*
+
+the PowerDNS server won't start up and you will see a fatal error in the
+log file. For a list of available parameters, please have a look at
+[configuration
+options](PowerDNS_LDAP_Backend/Installation#Configuration_options "wikilink").
+
+Use of quotation marks ("")
+---------------------------
+
+Do never use quotation marks in the PowerDNS configuration files! They
+are not evaluated and remain part of the parameter value. This leads to
+hard to find errors, e.g. no objects are returned from the LDAP
+directory.
+
+No reverse zone transfer
+------------------------
+
+Your LDAP tree must contain a separate subtree of PTR records (e.g. for
+1.1.10.10.in-addr.arpa) and you can't set "ldap-method" to "strict".
+
+IPv6 reverse lookup doesn't work in strict mode
+-----------------------------------------------
+
+For automatically generated reverse IPv6 records your aAAARecord entries
+must follow two restrictions: They have to be fully expanded ("FFFF::1"
+is not allowed and it must be "FFFF:0:0:0:0:0:0:1" instead) and they
+must not contain leading zeros, e.g. an entry containing "002A" is
+incorrect - use "2A" without zeros instead. These restrictions are due
+to the fact that LDAP DNS AAAA entries are pure text and doesn't allow
+searching by wild-cards.
+
+Bad search filter
+-----------------
+
+The release of PowerDNS 2.9.20 contains a bug in
+ldap-filter-{axfr,lookup}. A user provided string with ":target:" is
+replaced with "(associatedDomain=QUERYDATA)" and braces ARE added. So if
+you create some filter like
+
+`ldap-filter-lookup=(&(:target:)(active=yes))`
+
+it will result as
+
+`ldap-filter-lookup=(&((associatedDomain=QUERYDATA))(active=yes))`
+
+which results with bad search filter. To circumvent the bug temporarily
+you can add instead
+
+`ldap-filter-lookup=(&:target:(active=yes))`
+
+The bug will be fixed in version 2.9.21 and later versions.
+
+------------------------------------------------------------------------
+
+**Feel free to add your own tips**
+
+TITLE: FUTURE
+
+DNS notification support
+------------------------
+
+As soon as the LDAP server implementations begin to provide the features
+of the LDAP client update protocol (LCUP, [RFC
+3928](http://www.ietf.org/rfc/rfc3928.txt)), it will be possible to
+support the DNS notification feature for the [LDAP DNS
+backend](PowerDNS_LDAP_Backend "wikilink") in case a record in the LDAP
+directory was changed.
+
+SASL support
+------------
+
+Support for more authentication methods would be handy. Anyone
+interested and willing to contribute?
projects / thirdparty / pdns.git / commitdiff
