---
name: "inadyn"
section: "8"
platform: "linux"
package: "inadyn"
version: "2.11.0-1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/inadyn"
---

# inadyn(8)

Internet Automated Dynamic DNS Client

## NAME

**inadyn** – Internet Automated Dynamic DNS Client

## SYNOPSIS

**inadyn** \[**-1,** **--once**\] \[**--force**\] \[**--cache-dir** *PATH*\] \[**-c,** **--cmd** */path/to/cmd*\] \[**-C,** **--continue-on-error**\] \[**-e,** **--exec** */path/to/cmd*\] \[**--exec-mode** *MODE*\] \[**-f,** **--config** *FILE*\] \[**-h,** **--help**\] \[**-i,** **--iface** *IFNAME*\] \[**-I,** **--ident** *NAME*\] \[**-l,** **--loglevel** *LEVEL*\] \[**-L,** **--list-providers**\] \[**-n,** **--foreground**\] \[**--no-pidfile**\] \[**-P,** **--pidfile** *FILE*\] \[**-p,** **--drop-privs** *USER*\[:*GROUP*\]\] \[**-s,** **--syslog**\] \[**-S,** **--show-provider** **-NAME**\] \[**-t,** **--startup-delay** *SEC*\] \[**-v,** **--version**\]

## DESCRIPTION

**inadyn**, or In-a-Dyn, periodically checks your actual Internet accessible IP for changes.  When it changes **inadyn** updates your name server record(s) automatically.

Common DDNS service providers supported by **inadyn** are listed below.  Some of these services are free of charge for non-commercial use, others take a small fee, but also provide more domain names to choose from.

**inadyn** defaults to HTTPS for all providers, some may however not support this so try disabling SSL for your provider in case of problems.  Providers known to support SSL updates are listed below with **https**. The list is ordered by the plugin that support the service:

- ⟨https://freedns.afraid.org⟩

- ⟨https://nsupdate.info⟩

- ⟨https://duckdns.org⟩

- ⟨https://freemyip.com⟩

- ⟨http://www.dyndns.org⟩, ⟨http://dyn.com⟩

  - ⟨http://dns.he.net⟩

  - ⟨https://www.dnsomatic.com⟩

  - ⟨https://domains.google⟩

  - ⟨https://www.dynu.com⟩

  - ⟨https://www.loopia.com⟩

  - ⟨http://www.noip.com⟩

  - ⟨https://www.pubyun.com⟩, formerly ⟨http://www.3322.org⟩

  - ⟨https://www.selfhost.de⟩

  - ⟨https://spdyn.de⟩

- ⟨http://www.easydns.com⟩

- ⟨http://www.tunnelbroker.net⟩

- ⟨http://www.sitelutions.com⟩

- ⟨http://www.dnsexit.com⟩, parent of ⟨https://zoneedit.com⟩

- ⟨http://www.changeip.com⟩

  - ⟨https://www.ovh.com⟩

  - ⟨https://www.strato.com⟩

- ⟨http://www.dhis.org⟩

- ⟨http://giradns.com⟩, ⟨https://gira.de⟩

- ⟨https://www.duiadns.net⟩

- ⟨https://ddnss.de⟩

- ⟨http://dynv6.com⟩

- ⟨http://ipv4.dynv6.com⟩

- ⟨https://www.cloudxns.net⟩

- ⟨https://www.dnspod.cn⟩

- ⟨https://connect.yandex.ru⟩

- ⟨https://www.cloudflare.com⟩

- ⟨https://www.goip.de⟩

DDNS providers not listed here, e.g. ⟨https://www.namecheap.com⟩, can often be configured using the custom DDNS provider plugin.  See [inadyn.conf(5)](/inadyn.conf/5.md) for examples.

## OPTIONS

Earlier versions of **inadyn** supported more command line options, from v2.0 **inadyn** has been greatly simplified.  See [inadyn.conf(5)](/inadyn.conf/5.md) for details of the */etc/inadyn.conf* configuration file format.

- **-1,** **--once**

  Run only once and quit, updates only if too old or unknown.  Use **--force** to for an update before exiting.

- **--force**

  Force one update.  Only works with **-1,** **--once** flag, ignored for all other use-cases.

- **--cache-dir** *PATH*

  Set directory for persistent cache files, defaults to */var/cache/inadyn*

  The cache files are used to keep track of which addresses have been successfully sent to their respective DDNS provider and when.  The latter 'when' is important to prevent **inadyn** from banning you for excessive updates.

  When restarting **inadyn** or rebooting your server, or embedded device, **inadyn** reads the cache files to seed its internal data structures with the last sent IP address and when the update was performed.  It is therefore very important to both have a cache file and for it to have the correct time stamp.  The absence of a cache file will currently cause a forced update.

  On an embedded device with no RTC, or no battery backed RTC, it is strongly recommended to pair this setting with the **--startup-delay** *SEC* command line option.

- **-c,** **--cmd** */path/to/cmd* \[optional args\]

  Full path to command, or script, to run to check for IP address change. This is the same as the configuration file option *checkip-command* but will apply to **all** providers.  This command line option is only provided for convenience, it is recommended to instead use the configuration file.  For more details, see the [inadyn.conf(5)](/inadyn.conf/5.md) man page.  You will need to quote the complete command if any arguments, or pipe, is given.

- **--continue-on-error**

  Ignore errors from DDNS provider and try again later.  This command line option tells **inadyn** to not exit on errors from a DDNS provider and instead try again later. Please do not use this, it usually indicates that we are sending a malformed request, e.g. wrong username, password or DNS alias for the given account.  Continuing could possibly lock you out of your account!

- **-e,** **--exec=/path/to/cmd** \[optional args\]

  Full path to command, or script, to run. The following environment variables are set: INADYN\_IP, INADYN\_HOSTNAME. The first environment variable contains the new IP address, the second the host name alias.  The **cmd** is called for each listed host name.  If **inadyn** is started with the **-i** *IFNAME* command line option, the INADYN\_IFACE environment variable is also set. You will need to quote the complete command if any arguments, or pipe, is given.

- **--exec-mode** *MODE*

  Use *MODE* to set the exec script run mode: compat, event: - compat: run exec handler on successful DDNS update only, default - event: run exec handler on any update status The following environment variables are set: INADYN\_EVENT, INADYN\_ERROR, INADYN\_ERROR\_MESSAGE. INADYN\_EVENT contains the event, one of: nochg, update, error. The event nochg indicates that no update had to be sent, the event update indicates that an update was sent successully, the event error indicates that the update was sent and an error occurred. INADYN\_ERROR contains the error code, INADYN\_ERROR\_MESSAGE contains the error message for the error code.

- **-f,** **--config** *FILE*

  Use *FILE* for configuration. By default */etc/inadyn.conf*, is used.  See [inadyn.conf(5)](/inadyn.conf/5.md) for examples.

- **-h,** **--help**

  Show summary of command line options and exit

- **-i,** **--iface** *IFNAME*

  Check IP of IFNAME instead of querying an external server.  With this command line option the external IP check is disabled and **inadyn** will report the IP address of *IFNAME* to all DDNS providers listed in the configuration file.  This can be useful to register LAN IP addresses, or, when connected directly to a public IP address, to speed up the IP check if the DDNS provider's check-ip servers are slow to respond.

  This option can also be given as a configuration option in [inadyn.conf(5)](/inadyn.conf/5.md), both serve a purpose, use whichever one works for you.

- **-I,** **--ident** *NAME*

  Specify program identity (name) to be used for PID file and syslog messages.  Useful with multiple instances of **inadyn**, or to simply replace the **inadyn** name with something more generic, e.g. "DDNS", without renaming the binary.  Note, this option only changes the base name of the PID file, not the location, which is system specific.  Usually */var/run/inadyn.pid* or */run/inadyn.pid*.

- **-l,** **--loglevel** *LEVEL*

  Set log level: none, err, info, *notice*, debug.  The default is *notice*, but you might want to set this to **-l** *warning*.

- **-l,** **--list-providers**

  List available DDNS providers.

- **-n,** **--foreground**

  Run in foreground, default is to daemonize and continue in the background.  This option is usually required when running under process supervisors like systemd and Finit, but is also useful when running from the terminal, when debugging a config or at initial set up.  Remember to also give the **-s** option if you still want to redirect log messages to the syslog.

- **-p,** **--drop-privs** *USER*\[:*GROUP*\]

  Drop root privileges after initial setup to the given user and group.

- **--no-pidfile**

  When running as a daemon, even when running in the foreground with **-n**, **inadyn** creates a PID file so users can easily find the PID of the process to send signals to.  See SIGNALS for more information on this.  This option tells **inadyn** to **not** create a PID file.  Some users prefer this when running under systemd.

- **-P,** **--pidfile** *FILE*

  Set PID file name and location, defaults to */run/inadyn.pid*, derived from **--ident** *NAME*, which is strongly recommended to change over this option.  However, some users want to keep application runtime files in separate directories, usually in combination with **--drop-privs**, for such cases this is the option to use.

- **-s,** **--syslog**

  Use [syslog(3)](/syslog/3.md) for log messages, warnings and error conditions.  This is the default when running in the background.  When running in the foreground, see **-n**, log messages are printed to stdout.

- **-S,** **--show-provider** *NAME*

  Show information about DDNS provider *NAME*, substring search supported.

- **-t,** **--startup-delay** *SEC*

  Initial startup delay.  Default is 0 seconds.  Any signal can be used to abort the startup delay early, but SIGUSR2 is the recommended to use. See SIGNALS below for full details of how **inadyn** responds to signals.

  Intended to allow time for embedded devices without a battery backed real time clock to set their clock via NTP at bootup.  This is so that the time since the last update can be calculated correctly from the **inadyn** cache file and the **forced-update** *SEC* setting honored across reboots, avoiding unnecessary IP address updates.

- **-v,** **--version**

  Show program version and exit.

## OUTPUT

**inadyn** prints a message when the IP is updated.  If no update is needed then by default it prints a single “.” character, unless **--loglevel** is set to *none*. Therefore, unless **--loglevel** is set to *none*, the log will contain lots of dots.  When the connection goes down **inadyn** may print some harmless error messages which should be followed by “OK” messages after the Internet connection is restored.

## SIGNALS

**inadyn** responds to the following signals:

- HUP

  Reload the **.conf** file, standard UNIX behavior

- TERM

  Tell **inadyn** to exit gracefully

- INT

  Same as TERM

- USR1

  Force update now, even if the IP address has not changed

- USR2

  Check IP address change now. Useful when a new DHCP/PPPoE lease or new gateway is received.  Please note that **inadyn** does not track such events by itself.  You need an external monitor for that

For convenience in sending signals, **inadyn** writes its process ID to */var/run/inadyn.pid*, unless the **--ident** *NAME* option is used.

## FILES

- */etc/inadyn.conf*

  - */run/inadyn.pid*

  - */var/cache/inadyn/dyndns.org.cache*

  - */var/cache/inadyn/freedns.afraid.org.cache*

  - *...* *one* *.cache* *file* *per* *DDNS* *provider*

  ## SEE ALSO

[inadyn.conf(5)](/inadyn.conf/5.md)

The **inadyn** home page is at GitHub: ⟨https://github.com/troglobit/inadyn⟩

## AUTHORS

**inadyn** was originally written by Narcis Ilisei ⟨mailto:inarcis2002@hotpop.com⟩ and Steve Horbachuk.  Current patch monkey is Joachim Wiberg ⟨mailto:troglobit@gmail.com⟩ with a lot of help from Andrey Tikhomirov and Mike Fleetwood.

This manual page was originally written for the *Debian* *GNU/Linux* project by Shaul Karl ⟨mailto:shaul@debian.org⟩, and is currently maintained by Joachim Wiberg.