Unbound is a validating, recursive, and caching DNS resolver. Currently it’s only used only as DNS server for anti-spam DNSBL implementation.

When a new mail arrives, the anti-spam filter checks if sender IP address is listed in well-known blacklists. Some blacklists doesn’t allow multiple query from public DNS servers, thus the system needs a DNS server which can directly query the blacklist DNS.

If the mail filter is installed, dnsmasq configuration is changed, and specific domain query are redirect trough unbond. See: /etc/e-smith/templates/etc/dnsmasq.conf/26unbound_rbl.

Package: nethserver-unbound.


Configuration is saved in unbound key inside configuration database.

Available properties:

  • UDDPort: server address of the mail server, default is localhost
  • access: default is none since unbound should not be used as a normal DNS server
  • status: can be enabled or disabled, default is enabled



Configuration can be applied using the nethserver-unbound-update event.