Notable changes since v3.11.2:
Breaking changes


ddclient now looks for ddclient.conf in ${sysconfdir}/ddclient by default instead of ${sysconfdir}.  #789
To retain the previous behavior, pass '--with-confdir=${sysconfdir}' to configure.  For example:
# Before v4.0.0:
./configure --sysconfdir=/etc
# Equivalent with v4.0.0 and later (the single quotes are intentional):
./configure --sysconfdir=/etc --with-confdir='${sysconfdir}'
or:
# Before v4.0.0:
./configure --sysconfdir=/etc/ddclient
# Equivalent with v4.0.0 and later:
./configure --sysconfdir=/etc


The --ssl option is now enabled by default.  #705


Unencrypted (plain) HTTP is now used instead of encrypted (TLS) HTTP if the URL uses http:// instead of https://, even if the --ssl option is enabled.  #608


The string argument to --cmdv4 or --cmdv6 is now executed as-is by the system's shell, matching the behavior of the deprecated --cmd option.  This makes it possible to pass command-line arguments, which reduces the need for a custom wrapper script.  Beware that the string is also subject to the shell's command substitution, quote handling, variable expansion, field splitting, etc., so you may need to add extra escaping to ensure that any special characters are preserved literally.  #766


The default web service for --webv4 and --webv6 has changed from Google Domains (which has shut down) to ipify.  5b104ad1


Invalid command-line options or values are now fatal errors (instead of discarded with a warning).  #733


All log messages are now written to STDERR, not a mix of STDOUT and STDERR.  #676


For --protocol=freedns and --protocol=nfsn, the core module Digest::SHA is now required.  Previously, Digest::SHA1 was used (if available) as an alternative to Digest::SHA.  #685


The he built-in web IP discovery service (--webv4=he, --webv6=he, and --web=he) was renamed to he.net for consistency with the new he.net protocol.  The old name is still accepted but is deprecated and will be removed in a future version of ddclient.  #682


Deprecated built-in web IP discovery services are not listed in the output of --list-web-services.  #682


dyndns2: Support for "wait" response lines has been removed.  The Dyn documentation does not mention such responses, and the code to handle them, untouched since at least 2006, is believed to be obsolete.  #709


dyndns2: The obsolete static and custom options have been removed.  Setting the options may produce a warning.  #709


The diagnostic --geturl command-line argument was removed.  #712


easydns: The default value for min-interval was increased from 5m to 10m to match easyDNS documentation.  #713


woima: The dyn.woima.fi service appears to be defunct so support was removed.  #716


googledomains: Support was removed because the service shut down.  #716


The --retry option was removed.  #732


New features

New --mail-from option to control the "From:" header of email messages.  #565
Simultaneous/separate updating of IPv4 (A) records and IPv6 (AAAA) records is now supported in the following services: gandi (#558), nsupdate (#604), noip (#603), mythicdyn (#616), godaddy (#560).
porkbun: Added support for subdomains.  #624
gandi: Added support for personal access tokens.  #636
Comments after the \ line continuation character are now supported.  3c522a7a
Minor improvements to --help output.  #659, #665
Improved formatting of ddclient's version number.  #639
Updated sample systemd service unit file to improve logging in the systemd journal.  #669
The second and subsequent lines in a multi-line log message now have a different prefix to distinguish them from separate log messages.  #676 #719
Log messages now include context, making it easier to troubleshoot issues.  #725
emailonly: New protocol option that simply emails you when your IP address changes.  #654
he.net: Added support for updating Hurricane Electric records.  #682
dyndns2, domeneshop, dnsmadeeasy, keysystems: The server option can now include http:// or https:// to control the use of TLS.  If omitted, the value of the ssl option is used to determine the scheme.  #703
ddns.fm: New protocol option for updating DDNS.FM records.  #695
inwx: New protocol option for updating INWX records.  #690
domeneshop: Add IPv6 support.  #719
duckdns: Multiple hosts with the same IP address are now updated together.  #719
directnic: Added support for updatng Directnic records.  #726
porkbun: The update URL hostname is now configurable via the server option.  #752
dnsexit2: Multiple hosts are updated in a single API call when possible.  #684

Bug fixes

Fixed numerous bugs in cache file (recap) handling.  #740
Fixed numerous bugs in command-line option and configuration file processing.  #733
noip: Fixed failure to honor IP discovery settings in some circumstances.  #591
Fixed --usev6 with providers that have not yet been updated to use the new separate IPv4/IPv6 logic.  ad854ab7
HTTP redirects (301, 302) are now followed.  #592
keysystems: Fixed update URL.  #629
dondominio: Fixed response parsing.  #646
Fixed --web-ssl-validate and --fw-ssl-validate options, which were ignored in some cases (defaulting to validate).  #661
Explicitly setting --web-skip, --webv4-skip, --webv6-skip, --fw-skip, --fwv4-skip, and --fwv6-skip to the empty string now disables any built-in default skip.  Before, setting to the empty string had no effect.  #662
--use=disabled now works.  #665
--retry and --daemon are incompatible with each other; ddclient now errors out if both are provided.  #666
--usev4=cisco and --usev4=cisco-asa now work.  #664
Fixed "Scalar value better written as" Perl warning.  #667
Fixed "Invalid Value for keyword 'wtime' = ''" warning.  #734
Fixed unnecessary repeated updates for some services.  #670 #732
Fixed DNSExit provider when configured with a zone and non-identical hostname.  #674
infomaniak: Fixed frequent forced updates after 25 days (max-interval).  #691
infomaniak: Fixed incorrect parsing of server response.  #692
infomaniak: Fixed incorrect handling of nochg responses.  #723
regfishde: Fixed IPv6 support.  #691
easydns: IPv4 and IPv6 addresses are now updated separately to be consistent with the easyDNS documentation.  #713
easydns: Fixed parsing of result code from server response.  #713
easydns: Fixed successful updates treated as failed updates.  #713
Any IP addresses in an HTTP response's headers or in an HTTP error response's body are now ignored when obtaining the IP address from a web-based IP discovery service (--usev4=webv4, --usev6=webv6) or from a router/firewall device.  #719
yandex: Errors are now retried.  #719
gandi: Fixed handling of error responses.  #721
dyndns2: Fixed handling of responses for multi-host updates.  #728
porkbun: The default update URL was updated from porkbun.com to api.porkbun.com.  #752