Entries in this section are used by the client to determine the intermediate realms which may be used in cross-realm authentication. It is also used by the end-service when checking the transited field for trusted intermediate realms. Set its value to your Kerberos realm. If this is not specified and the TXT record lookup is enabled see Using DNS , then that information will be used to determine the default realm.
If this tag is not set in this configuration file and there is no DNS information found, then an error will be returned. The list may be delimited with commas or whitespace. Kerberos supports many different encryption types, and support for more is planned in the future. The default value is aescts-hmac-sha aescts-hmac-sha des3-cbc-sha1 arcfour-hmac-md5 des-cbc-crc des-cbc-md5 des-cbc-md4.
The default value for this tag is aescts-hmac-sha aescts-hmac-sha des3-cbc-sha1 arcfour-hmac-md5 des-cbc-crc des-cbc-md5 des-cbc-md4. The default value for this tag is false, which may cause authentication failures in existing Kerberos infrastructures that do not support strong crypto. Users in affected environments should set this tag to true until their infrastructure adopts stronger ciphers. The default value is seconds, or five minutes.
This option can improve the administrative flexibility of server applications multi-homed hosts, but can compromise the security of virtual hosting environments. The default value is false. If the value of this relation is false, a principal may still be granted login access through other mechanisms even if a k5login file exists but does not list the principal.
If not set, the library will look for k5login files in the user's home directory, with the filename. For security reasons, k5login files must be owned by the local user or by root. This corrective factor is only used by the Kerberos library. The default is 1. If set, then the selected checksum is used regardless of the type of key being used. The possible values and their meanings are as follows. The default value for this setting is "17, 16, 15, 14", which forces libkrb5 to attempt to use PKINIT if it is supported. DCE and Kerberos can share the cache, but some versions of DCE do not support the default cache as created by this version of Kerberos.
Use a value of 1 on DCE 1. The default value is 4. Enabling this option does open up a type of denial-of-service attack, if someone spoofs the DNS records and redirects you to another server. However, it's no worse than a denial of service, because that fake KDC will be unable to decode anything you send it besides the initial ticket request, which has no encrypted data , and anything the fake KDC sends will not be trusted without verification using some secret that it won't know.
If neither option is specified, the behavior depends on configure-time options; if none were given, the default is to enable this option. If the DNS support is not compiled in, this entry has no effect. Enabling this option may permit a redirection attack, where spoofed DNS replies persuade a client to authenticate to the wrong realm, when talking to the wrong host either by spoofing yet more DNS records or by intercepting the net traffic. Depending on how the client software manages hostnames, however, it could already be vulnerable to such attacks.
We are looking at possible ways to minimize or eliminate this exposure. For now, we encourage more adventurous sites to try using Secure DNS. If neither option is specified, the behavior depends on configure-time options; if none were given, the default is to disable this option. If both of the preceding options are specified, this option has no effect. The value of this variable is an integer: -1 means not to search, 0 means to try the host's domain itself, 1 means to also try the domain's immediate parent, and so forth. The default is not to search domain components. The addresses should be in a comma-separated list.
Regardless of the size, both protocols will be tried if the first attempt fails. The default for the flag is not set. The default value for the tag is 1 day. The default value for the tag is 0. The default for the flag is set. The default value for this flag is not set. Defaults to true. Setting this flag to false is more secure, but may force users to exclusively use fully qualified domain names when authenticating to services. The value of the tag defines the default behaviors for that application.
Kerberos V5 System Administrator's Guide
COM, it should, by default, have option1 and option2 set to true. EDU should have option1 set to false and option2 set to true. EDU should have option2 set to false by default. Any programs running in other realms should have option2 set to true. The list of specifiable options for each application may be found in that application's man pages. The application defaults specified here are overridden by those specified in the [realms] section. The default value is true. This is not yet implemented. The value of the tag is a subsection with relations that define the properties of that particular realm.
For each realm, the following tags may be specified in the realm's subsection: kdc The name or address of a host running a KDC for that realm. An optional port number, separated from the hostname by a colon, may be included. If the name or address contains colons for example, if it is an IPv6 address , enclose it in square brackets to distinguish the colon from a port separator.
Currently, this tag is used in only one case: If an attempt to get credentials fails because of an invalid password, the client software will attempt to contact the master KDC, in case the user's password has just been changed, and the updated database has not been propagated to the slave servers yet. Typically, this is the master Kerberos server. This tag must be given a value in order to communicate with the kadmin server for the realm. Kerberos 4 does not require the entire hostname of a server to be in its principal like Kerberos 5 does. This tag provides the domain name needed to produce a full hostname when translating V4 principal names into V5 principal names.
It contains V4 instances the tag name which should be translated to some specific hostname the tag value as the second component in a Kerberos V5 principal name. It is used when the V4 realm name and the V5 realm name are not the same, but still share the same principal names and passwords. The tag value is the Kerberos V4 realm name. The tag is the mapping name, and the value is the corresponding local user name. It will be used if there is not an explicit mapping for the principal name that is being translated. The possible values are: DB: filename The principal will be looked up in the database filename.
Support for this is not currently compiled in by default. RULE: exp The local name will be formulated from exp. The integer n indicates how many components the target principal should have. The optional g will cause the substitution to be global over the string, instead of replacing only the first match in the string. If the principal has more than one component or is not in the default realm, this rule is not applicable and the conversion will fail.
A principal with a second component of admin will become its first component. The value of the relation is the Kerberos realm name for that particular host or domain. Host names and domain names should be in lower case. If no translation entry applies, the host's realm is considered to be the hostname's domain portion converted to upper case.
EDU mit. EDU crash. EDU example. COM maps crash. EDU realm. All other hosts in the mit. EDU realm, and all hosts in the example. COM realm. Note the entries for the hosts mit. The relations in this section assign one or more values to the entity name. Currently, the following entities are used: kdc These entries specify how the KDC is to perform its logging. The severity argument specifies the default severity of system log messages. The facility argument specifies the facility under which the messages are logged.
If no severity is specified, the default is ERR. If no facility is specified, the default is AUTH. This section defines that database. A client will use this section to find the authentication path between its realm and the realm of the server. The server will use this section to verify the authentication path used by the client, by checking the transited field of the received ticket. There is a tag for each participating realm, and each tag has subtags for each of the realms.
The value of the subtags is an intermediate realm which may participate in the cross-realm authentication.
The subtags may be repeated if there is more then one intermediate realm. A value of ". The client needs a tag for its local realm, with subtags for all the realms of servers it will need to authenticate with. A server needs a tag for each realm of the clients it will serve. For example, ANL. GOV all wish to use the ES. NET realm as an intermediate realm. The [capaths] section for ANL.
NET ES. The client will use this to determine the path. It is not important to the server, since the transited field is not sorted. This feature is not currently supported by DCE. It can also specify the configuration section under [dbmodules] section for database specific parameters used by the database library. This value is used if the container object is not mentioned in the configuration section under [dbmodules]. The KDC server does a login to the directory as this object. This value is used if the bind DN for the KDC is not mentioned in the configuration section under [dbmodules].
The administration server does a login to the directory as this object. This value is used if the bind DN for the Administration server is not mentioned in the configuration section under [dbmodules]. This file must be kept secure. This value is used if no service password file is mentioned in the configuration section under [dbmodules]. The list of LDAP servers is whitespace-separated. This value is used if no LDAP servers are mentioned in the configuration section under [dbmodules]. This value is used if the number of connections per LDAP server are not mentioned in the configuration section under [dbmodules].
The default value is 5. Each tag in the [dbmodules] section of the file names a configuration section for database specific parameters that can be referred to by a realm. The value of the tag is a subsection where the relations in that subsection define the database specific parameters. Setting this flag may improve performance.
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Setting this flag may improve performance, but also disables account lockout. Not every krb5 pluggable interface uses the [plugins] section; the ones that do are documented here. Each pluggable interface corresponds to a subsection of [plugins]. All subsections support the same tags: module This tag may have multiple values. Each value is a string of the form "modulename:pathname", which causes the shared object located at pathname to be registered as a dynamic module named modulename for the pluggable interface.
If there are values for this tag, then only the named modules will be enabled for the pluggable interface. If there are values for this tag, then the named modules will be disabled for the pluggable interface. This interface can be used to write a plugin to synchronize MIT Kerberos with another database such as Active Directory. No plugins are built in for this interface. Note that these values may be specified in [libdefaults] as global defaults, or within a realm-specific subsection of [libdefaults] , or may be specified as realm-specific values in the [realms] section.
Also note that a realm-specific value over-rides, does not add to, a generic [libdefaults] specification. If key-file-name is not specified, the user's private key is expected to be in file-name as well.
Otherwise, key-file-name is the name of the file containing the private key. DIR: directory-name This option has context-specific behavior. When a file with a name ending with. If no such file is found, then the certificate in the. This infrastructure is encouraged, but all files in the directory will be examined and if they contain certificates in PEM format , they will be used.
This infrastructure is encouraged, but all files in the directory will be examined and if they contain a revocation list in PEM format , they will be used. If a value is encountered with no keyword, it is assumed to be the module-name. If no module-name is specified, the default is opensc-pkcs ENV: environment-variable-name environment-variable-name specifies the name of an environment variable which has been set to a value conforming to one of the previous values.
This option may be specified multiple times. Each value is attempted in order until identity information is found and authentication is attempted. If a match is found for the certificate in a CRL, verification fails. The acceptable values are currently , , and The default is The default is false. The values recognized in the krb5. The use of this option is not recommended. Its value should contain the acceptable hostname for the KDC as contained in its certificate. If a user has multiple certificates available on a smart card, or via other media , there must be exactly one certificate chosen before attempting pkinit authentication.
All the available certificates are checked against each rule in order until there is a match of exactly one certificate. The syntax of the matching rules is: [ relation-operator ] component-rule Note that there is no punctuation or whitespace between component rules. All values in the list must be present in the certificate.
Normally, you should install your kdc. The kdc. See krb5. This list is a comma separated list of integers. If this relation is not specified, the compiled-in default is 88,, the first being the assigned Kerberos port and the second which was used by Kerberos V4. If this relation is not specified, the compiled-in default is not to listen for TCP connections at all. If you wish to change this which we do not recommend, because the current implementation has little protection against denial-of-service attacks , the standard port number assigned for Kerberos TCP traffic is port The value of the tag is a subsection where the relations in that subsection define KDC parameters for that particular realm.
Location of the access control list acl file that kadmin uses to determine which principals are allowed which permissions on the database. Location of the keytab file that the legacy administration daemons kadmind4 and v5passwdd use to authenticate to the database.
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Specifies the default expiration date of principals created in this realm. The default value for this tag is 0. Specifies the default attributes of principals created in this realm. The default is postdateable, forwardable, tgt-based, renewable, proxiable, dup-skey, allow-tickets, and service enabled.. There are a number of possible flags: postdateable Enabling this flag allows the principal to obtain postdateable tickets. Disabling this flag essentially deactivates the principal within this realm.
On a service principal, enabling this flag means that service tickets for this principal will only be issued to clients with a TGT that has the preauthenticated ticket set. This should only be used in special cases, for example, if a user's password has expired, then the user has to get tickets for that principal without going through the normal password authentication in order to be able to change the password. Location of the dictionary file containing strings that are not allowed as passwords.
If none is specified or if there is no policy assigned to the principal, no dictionary checks of passwords will be performed. Specifies the port on which the kadmind daemon is to listen for this realm.
The assigned port for kadmind is Specifies the port on which the kpasswd daemon is to listen for this realm. Specifies the name of the principal associated with the master key. Specifies the master key's key type. The default value for this is des3-cbc-sha1. For a list of all possible values, see Supported Encryption Types.
Specifes the maximum time period for which a ticket may be valid in this realm. An excellent study guide and good general reference to boot. The authors do an excellent job of handling complex topics in a clear, logical manner. That said, I've never met him personally, and if his book wasn't worthy of a decent review I wouldn't give it one. For example, look at how the book explains secondary DNS servers. In three concise paragraphs it explains that: a secondary DNS server contains the same information as a primary, it can be used to resolve DNS requests, and is generally used to provide fault tolerance.
However there's a trade-off due to increased replication traffic. Go ahead, humor me and look it up now. See the difference? This book offers clarity rather than confusion. The book includes an excellent map to Microsoft's objectives for the exam. This is extremely helpful if you like—as I do—to organize your studying by exam objective.
I loved the dictionary of networking terms on the accompanying CD and actually got sidetracked a bit by browsing through the information on it. It enables us to resolve names even if they are illegal. It is, in spite of the option to allow everything, a good idea to stay on the right side of the RFCs.
If you use illegal characters in hostnames, you risk people on the Internet or even in your own company being unable to resolve names because their resolver implementations are less graceful than yours. So, just say no to illegal names. Previous page. Table of content. Next page. Authors: Nicolai Langfeldt. Special Edition Using FileMaker 8. VBScript Programmers Reference. Cisco CallManager Fundamentals 2nd Edition. If you may any questions please contact us: flylib qtcs.