rollerd man page

rollerd — DNSSEC-Tools daemon to manage DNSSEC key rollover


rollerd [-options] -rrfile <rollrec_file>


The rollerd daemon manages key rollover for zones. rollerd is just a scheduler for zone rollover; it uses zonesigner to perform the actual key generation, zone signing, and key manipulation.

rollerd manages both KSK and ZSK rollover, though only one rollover type per zone may take place at a time. Initiation of KSK rollovers takes precedence over the initiation of ZSK rollovers.

rollerd uses two methods of key rollover. The Pre-Publish Method of key rollover is used for ZSK key rollovers. The Double Signature Method of key rollover is used for KSK rollovers. These methods are described more fully below.

rollerd maintains zone rollover state in files called rollrec files; zone/key mappings are stored in keyrec files. rollerd only modifies rollrec files. For the most part, rollerd does not modify keyrec directly, but relies on zonesigner to update those files as needed. (The exceptions where rollerd modifies keyrec files. At start-up, it will mark each managed zone's keyrec file to indicate the zone is under rollerd's control. During the course of rollover, rollerd will also update a zone's rollover times in its keyrec file.)

The administrator may control rollerd with the rollctl command. A large number of commands are available to control and modify rollerd's operation, as well as to retrieve information about rollover and daemon status.

The zone administrator will need to update their zone files periodically. If rollerd is managing zones, then problems could arise if modified zones were signed without rollerd's knowledge. To prevent such problems, rollerd can be configured to automatically re-sign a zone when its zonefile is found to be newer than its corresponding signed zonefile. (The files' "last modification" timestamps are compared.) The zone will be re-signed without any other rollover actions taking place, so no new keys will be generated, no key rollovers will occur, and the various rollover timers will be unaffected.

rollerd will perform these re-signs by default, but this can be further controlled by the autosign configuration parameter and rollerd's -autosign/-noautosign command line options. If rollerd is configured to not perform automatic re-signing, the administrator can still get this controlled behavior by use of the zonesigner or rollctl commands.

If the rollrec file does not exist or is of zero length, rollerd will give an error message and continue running. It will periodically wake up and check for a usable rollrec file. Once it finds the specified rollrec file exists and isn't empty, then it will proceed with normal rollover management.

ZSK Rollover Using the Pre-Publish Method

The Pre-Publish Method has four phases that are entered when it is time to perform ZSK rollover:

1. wait for old zone data to expire from caches
2. sign the zone with the KSK and Published ZSK
3. wait for old zone data to expire from caches
4. adjust keys in keyrec and sign the zone with new Current ZSK

rollerd uses the zonesigner command during ZSK rollover phases 2 and 4. zonesigner will generate keys as required and sign the zone during these two phases.

The Pre-Publish Method of key rollover is defined in the Step-by-Step DNS Security Operator Guidance Document. See that document for more detailed information.

KSK Rollover Using the Double Signature Method

The Double Signature Method has seven phases that are entered when it is time to perform KSK rollover:

1 - wait for cache data to expire
2 - generate a new (published) KSK and load zone
3 - wait for the old DNSKEY RRset to expire from caches
4 - transfer new keyset to the parent
5 - wait for parent to publish DS record
6 - wait for cache data to expire
7 - roll the KSKs and load the zone

This is a modification of the original Double Signature Method. In the original method, the KSK keys were rolled before the new keyset was transferred to the parent. The new method rolls the KSK keys after the parent has published the new DS records and old data has expired for caches. This addresses a potential problem with signing zones during key rollovers.

rollerd uses the zonesigner command during KSK rollover phases 2 and 7. zonesigner will generate keys as required and sign the zone during these two phases.

Currently, leaving the waiting period in step 5 is handled manually. In step 4, rollerd informs the administrator via email that the zone's keyset must be transferred to its parent in order for rollover to continue. In step 5, after the keyset has been transferred to the parent and the parent has published a new DS record, the administrator uses rollctl to inform rollerd that the DS record has been published and rollover may continue.

The Double Signature Method of key rollover is defined in the Step-by-Step DNS Security Operator Guidance Document. See that document for more detailed information.

KSK Rollover Using the Double Signature Method and RFC5011

RFC5011 describes how remote-validating resolvers must track KSK changes within a zone. If configured for RFC5011 behavior, rollerd and zonesigner add an extra-long period of time between the point a new KSK is created and published and the point where the actual switch to using it takes place. RFC5011 specifies that remote validators should add a "hold-down timer" to the rollover process, such that the new key is not added as a trust-anchor until 30 days have past. Thus, rollerd will wait for 60 days (by default) during phase 3 of the KSK rollover process if the "istrustanchor" field of the rollrec definition has been set to either 1 or "yes". To wait for a different length of time other than 60 days, use the holddowntime field.

At this time, the other conventions of RFC5011 are not being followed. Specifically, it's not waiting for a while before removing the old key and it's not adding the revoke bit to the old key after switching.

Site-Specific Rollover Actions

An administrator can specify site-specific commands to be run during the various rollover phases. The commands can be run in place of the default rollerd rollover actions, or in addition to them. This subsection describes how to make use of site-specific rollover actions.

This capability is provided to allow different installations to handle rollover according to their specific needs. For example, it is anticipated that this might be helpful to sites using HSM hardware, or to allow for enhanced reporting to administrators. This has been used with simple test programs to ensure that it actually works. However, it has not yet been used in actual HSM environment or with other production-level software replacements.

See the ZSK Rollover Using the Pre-Publish Method and KSK Rollover Using the Double Signature Method sections for descriptions of the default rollover actions.

WARNING: This has the potential of being a dangerous capability. Be very careful when setting up and using it. Take care with the site-specific commands to be executed and the permissions and ownership of rollerd and its data files.

DNSSEC-Tools Configuration File Changes

The DNSSEC-Tools configuration file must be modified to tell rollerd what must be run for the non-default rollover phase actions. Key/value pairs may be set for each rollover phase to control how that phase differs from the default.

The value portion of the configuration entry contains the path to the site-specific phase command, along with any arguments it might need. Multiple commands are separated by bangs.

The reserved default command tells rollerd to use its normal rollover action for a particular phase. This may be combined with other commands to provide things such as specialized logging or notifications.

rollerd will only alter the behavior of a rollover phase if the configuration file contains an entry for that phase. If not, the default action will be taken.

For example, this configuration line tells rollerd that for ZSK rollover phase 2, instead of using its normal zonesigner executions it should run the hsm-signer command.

prog-zsk2        hsm-signer

In this example, this configuration line informs rollerd that when entering KSK rollover phase 1 and ZSK rollover phase 1, it should execute the log-and-mail command, then use the normal rollover action for those phases.

prog-ksk1        /usr/local/sbin/log-and-mail mary ! default
prog-zsk1        /usr/local/sbin/log-and-mail bob!default

The following configuration keys are used for controlling KSK rollover phases: prog-ksk1, prog-ksk2, prog-ksk3, prog-ksk4, prog-ksk5, prog-ksk6, and prog-ksk7,

The following configuration keys are used for controlling ZSK rollover phases: prog-zsk1, prog-zsk2, prog-zsk3, and prog-zsk4.

The prog-normal configuration key controls the normal, non-rollover state.

Site-Specific Commands

To be generally useful, the site-specific commands executed by rollerd will be given a standard set of arguments, and a standard set of exit values will be recognized.

The standard arguments from rollerd are:
1. zonename - Zone to be handled.
2. phase - Zone's current rollover phase (e.g., zsk1, ksk6, normal.)
3. rollrec name - Zone's entry key in the rollrec file.
4. rollrec file - The path to the rollrec file.
5. keyrec file - The path to the zone's keyrec file.

The prog-phase entry in the configuration file may specify additional options and arguments for a command. These will be included on the execution command line prior to the standard arguments.

The standard exit values expected by rollerd are:
0. The zone can move to the next rollover phase.
This is only applicable to the current command; other
commands in this phase's command list must still be run.
1. The zone should stay in the current rollover phase.
This is not necessarily the result of an error.
2. An error was found in the arguments given to the command.
3. An error was encountered during execution.

If a rollover phase's configuration entry lists multiple commands, they will be executed in the order listed. If any command in that command list fails, processing stops there.

The rp-wrapper command shows how a site-specific command may be written. rp-wrapper may be used as a skeleton on which to build a more useful rollover-phase command.

Considerations for Site-Specific Commands

The following should be taken into consideration when writing a site-specific command for a rollover phase.

execution length
A phase command should not execute very long. As currently written, rollerd serializes zone rollover. So the longer a phase command takes to execute, the longer it will take to get to the next zone. If a phase command sleeps or actively waits, so to speak, for the next phase timeout, then every zone rollerd manages will be left waiting.
follow interface guidelines
Follow the standards for arguments and exit values. Not following the standards is likely to negatively affect zone rollover.
frequency of command execution
If rollerd is operating in its traditional "full list" processing mode, a phase command list will be executed every time rollerd cycles through its zone list and a zone is in that particular command's phase. For example, if <i>prog_zsk1</i> is defined for example.com, that command list will be executed for example.com every time rollerd runs its zone list and finds example.com is in the ZSK phase 1 rollover state. A phase command must take this into account so it doesn't perform its actions more frequently than necessary. This is most likely an issue for the various rollover wait states, and possibly the normal state.

If rollerd is operating in the experimental "soon queue" processing mode, a phase command list will be executed for a zone only when a phase change occurs. Since phase changes are time queued, this should not happen more than once per phase. A phase command should take this into account, in case the soon queue is reordered before the zone leaves the queue, or queue timing is relatively swift. This is most likely an issue for the various rollover wait states.

WARNING: "soon queue" processing is experimental. Care should be taken when using this processing method, as it may still have some lingering bugs.

Zone Reloading

rollerd has the opportunity to inform the DNS daemon to reload a zone in KSK phase 2, KSK phase 7, ZSK phase 2, and ZSK phase 4. This is the rollerd's default behavior. However, there are situations where this shouldn't be done, such as for off-line signing.

The roll_loadzone field of the DNSSEC-Tools configuration file is a boolean field that overrides the default to force the zone-reload behavior either on or off. This field takes precedence over the default.

Similarly, the -noreload option prevents rollerd from requesting a zone reload, and it takes precedence over the roll_loadzone configuration field and the default.

rollrec Files

The zones to be managed by rollerd are described in a rollrec file. Generally speaking most people will want to use the rollinit command to create an initial rollrec file instead of typing their own from scratch. See the Initialization and Usage section below and the rollinit manual page for details. Each zone's entry contains data needed by rollerd and some data useful to a user. Below is a sample rollrec entry:

roll "example.com"
        zonename        "example.com"
        zonefile        "example.com.signed"
        keyrec          "example.com.krf"
        zonegroup       "demo-zones"
        directory       "dir-example.com"
        kskphase        "0"
        zskphase        "3"
        ksk_rollsecs    "1172614842"
        ksk_rolldate    "Tue Feb 27 22:20:42 2007"
        zsk_rollsecs    "1172615087"
        zsk_rolldate    "Tue Feb 27 22:24:47 2007"
        maxttl          "60"
        display         "1"
        phasestart      "Tue Feb 27 22:25:07 2007"
        # optional records for RFC5011 rolling:
        istrustanchor   "no"
        holddowntime    "60D"

The first line gives the rollrec entry's name. The name distinguishes it from other rollrec entries and must be unique. This may be the zone's name, but this is not a requirement. The following lines give the zone's name, the zone's signed zone file, keyrec file, the current rollover phases, the rollover timestamps, and other information. The zone group is optional and allows a set of related zones to be controlled with a single rollctl execution, rather than one execution per zone.

If either of the zonefile or keyrec files do not exist, then a "roll" rollrec will be changed into a "skip" rollrec. That record will not be processed.

A more detailed explanation may be found in rollrec(5).


rollerd's execution directory is either the directory in which it is executed or the directory passed in the -directory command-line option. Any files used by rollerd that were not specified with absolute paths use this directory as their base.

A rollrec file's directory field informs rollerd where the zone's files may be found. For that zone, rollerd will move into that directory, then return to its execution directory when it finishes rollover operations for that zone. If the directory value is a relative path, it will be appended to rollerd's execution directory. If the directory value is an absolute path, it will be used as is.

Controlling rollerd with rollctl

The rollctl command is used to control the behavior of rollerd. A number of commands are available, such as starting or stopping rollover for a selected zone or all zones, turning on or off a GUI rollover display, and halting rollerd execution. The communications path between rollerd and rollctl is operating system-dependent. On Unix-like systems, it is a Unix pipe that should only be writable by the user which runs rollerd. A more detailed explanation of rollctl may be found in rollctl(8).

A Note About Files and Filenames

There are a number of files and filenames used by rollerd and zonesigner. The user must be aware of the files used by these programs, where the files are located, and where the programs are executed.

By default, rollerd will change directory to the DNSSEC-Tools directory, though this may be changed by the -directory option. Any programs started by rollerd, most importantly zonesigner, will run in this same directory. If files and directories referenced by these programs are named with relative paths, those paths must be relative to this directory.

The rollrec entry name is used as a key to the rollrec file and to the zone's keyrec file. This entry does not have to be the name of the entry's domain, but it is a very good idea to make it so. Whatever is used for this entry name, the same name must be used for the zone keyrec in that zone's keyrec file.

It is probably easiest to store rollrec files, keyrec files, zone files, and key files in a single directory.

Initialization and Usage

The following steps must be taken to initialize and use rollerd. This assumes that zone files have been created, and that BIND and DNSSEC-Tools have been installed.

0. sign zones
The zones to be managed by rollerd must be signed. Use zonesigner to create the signed zone files and the keyrec files needed by rollerd. The rollrec file created in the next step must use the keyrec file names and the signed zone file names created here.

This step is optional. If it is bypassed, then (in step 4 and later) rollerd will perform the initial key creation and zone signing of your zones using the defaults found in the DNSSEC-Tools configuration file. rollerd determines if it must perform these initial operations by whether it can find the keyrec file for a zone (as specified in the rollrec file. If it can't, it performs the initial operations; if it can, it assumes the zone's initial operations have been performed.
1. create rollrec file
Before rollerd may be used, a rollrec file must first be created. While this file may be built by hand, the rollinit command was written specifically to build the file.
2. select operational parameters
A number of rollerd's operational parameters are taken from the DNSSEC-Tools configuration file. However, these may be overridden by command-line options. See the Options section below for more details. If non-standard parameters are desired to always be used, the appropriate fields in the DNSSEC-Tools configuration file may be modified to use these values.
3. install the rollover configuration
The complete rollover configuration -- rollerd, rollrec file, DNSSEC-Tools configuration file values, zone files -- should be installed. The appropriate places for these locations are both installation-dependent and operating system-dependent.
4. test the rollover configuration

The complete rollover configuration should be tested.

Edit the zone files so that their zones have short TTL values. A minute TTL should be sufficient. Test rollovers of this speed should only be done in a test environment without the real signed zone.

Run the following command:

rollerd -rrfile test.rollrec -logfile - -loglevel info -sleep 60

This command assumes the test rollrec file is test.rollrec. It writes a fair amount of log messages to the terminal, and checks its queue every 60 seconds. Follow the messages to ensure that the appropriate actions, as required by the Pre-Publish Method, are taking place.

5. set rollerd to start at boot
Once the configuration is found to work, rollerd should be set to start at system boot. The actual operations required for this step are operating system-dependent.
6. reboot and verify
The system should be rebooted and the rollerd logfile checked to ensure that rollerd is operating properly.


There are a number of operational parameters that define how rollerd works. These parameters define things such as the rollrec file, the logging level, and the log file. These parameters can be set in the DNSSEC-Tools configuration file or given as options on the rollerd command line. The command line options override values in the configuration file.

The following options are recognized:

Tells rollerd to sign the zones that aren't in the middle of being rolled. This allows rollerd to refresh signed zone signatures and allows complete management of zone signing to be taken over by rollerd.

The downside to using this option is that all the non-rolling zones will be signed after every sleep, which may be expensive computationally.

Note: The zone files are not updated or installed at this time. Manual copying and installation are still needed.
-autosign | -noautosign
Automatic zone-signing flag. If this is set, then a zone's zonefile will be re-signed (and only re-signed) if it is found to be newer than the corresponding signed zonefile.
-directory dir
Sets the rollerd execution directory. This must be a valid directory.
Starts the blinkenlights graphical display program to show the status of zones managed by rollerd.
-dtconfig config_file
Name of an alternate DNSSEC-Tools configuration file to be processed. If specified, this configuration file is used in place of the normal DNSSEC-Tools configuration file not in addition to it. Also, it will be handled prior to keyrec files, rollrec files, and command-line options.
Run in the foreground and do not fork into a daemon.
-logfile log_file
Sets the rollerd log file to log_file. This must be a valid logging file, meaning that if log_file already exists, it must be a regular file. The only exceptions to this are if logfile is /dev/stdout, /dev/tty, -. Of these three, using a log_file of - is preferable since Perl will properly convert the - to the process' standard output.
-loglevel level
Sets rollerd's logging level to level. rollmgr.pm(3) contains a list of the valid logging levels.
Prevents rollerd from telling the DNS daemon to reload zones.
Prints a set of rollerd parameters and then exits. This shows the parameters with which rollerd will execute, but very little parameter validation is performed.
-pidfile pid_file
Stores the running process PID into pid_file. This defaults to /var/run/rollerd.pid on most systems.
-rrfile rollrec_file
Name of the rollrec file to be processed. This is the only required "option".
-realm realm_name
Name of the realm in which rollerd is running. This is for use with the DNSSEC-Tools realms facility as a means of easily identifying different instantiations of rollerd. It is informational only (e.g., ps output and log files) and is not used for anything else.

Processes all needed steps once and exits. This is not the ideal way to run rollerd, but it is potentially useful for environments where keying material is only available when specific hardware tokens have been made available.

The timing between the steps will be potentially longer since the time between rollerd runs is dependent on when rollerd is executed. "cmd" lines must be added to the rollrec file to do particular actions.

The following lines should serve as examples:

cmd "rollzsk example.com"
cmd "rollksk example.com"
cmd "dspub example.com"   # (for when the parent publishes
                          # the new ksk)

The -singlerun option implicitly implies -foreground as well.

-sleep sleeptime
Sets rollerd's sleep time to sleeptime. The sleep time is the amount of time (in seconds) rollerd waits between processing its rollrec-based queue.
-username username
username is the user for which the rollerd daemon will be executed. The rollerd process' effective uid will be set to the uid corresponding to username.

If username is a username, it must correspond to a valid uid; if it is a uid, it must correspond to a valid username.

If rollerd does not have the appropriate O/S magic (e.g., for Unix, installed as setuid program and owned by root) then it will only be able to switch to those users to which the executing user has privilege to switch. This restriction is dependent on the operating system and the manner by which rollerd is installed.

When using this option, the target user must have access to the various directories, logs, and data files that rollerd requires to execute. Without this access, proper execution cannot occur.
-zsargs arglist

Additional zonesigner arguments that will be passed to all zonesigner executions. These arguments will override the corresponding arguments in the DNSSEC-Tools configuration file, and the zones' keyrec files. If a zone's rollrec entry contains a zsargs field, then it will be used instead of those specified by this argument.

Given the rollerd argument processing, the new arguments for zonesigner cannot be specified as expected. Instead, the arguments should be given in the following manner. The leading dash should be replaced with an equals sign. If the option takes an argument, the space that would separate the option from the option's argument should also be replaced by an equals sign. If multiple arguments will be passed via -zsargs, quotes must be used to group them into a single argument.

rollerd translates these arguments to the appropriate format for zonesigner. These examples should clarify the modifications:

normal zonesigner option     rollerd -zsargs option
------------------------     ----------------------
-nokrfile                    -zsargs =nokrfile
-zskcount 5 -kskcount 3      -zsargs "=zskcount=5 =kskcount=3"
Displays the version information for rollerd and the DNSSEC-Tools package.
Display a usage message.
Verbose output will be given.


rollerd uses the rndc command to communicate with the BIND named daemon. Therefore, it assumes that appropriate measures have been taken so that this communication is possible.

Known Problems

The following problems (or potential problems) are known:

Any process that can write to the rollover socket can send commands to rollerd. This is probably not a Good Thing.


Wayne Morrison, tewok@tislabs.com

See Also

blinkenlights(8), dtrealms(8), named(8), rndc(8), rp-wrapper(8), rollchk(8), rollctl(8), rollinit(8), zonesigner(8)

Net::DNS::SEC::Tools::conf.pm(3), Net::DNS::SEC::Tools::defaults.pm(3), Net::DNS::SEC::Tools::keyrec.pm(3), Net::DNS::SEC::Tools::rolllog.pm(3), Net::DNS::SEC::Tools::rollmgr.pm(3), Net::DNS::SEC::Tools::rollrec.pm(3)


Referenced By


Explore man page connections for rollerd(1).