最近ビルドに失敗するんだけど、

Configuring ppp-mod-pppoe.
Collected errors:
* satisfy_dependencies_for: Cannot satisfy the following dependencies for luci:
* rpcd-mod-rrdns *
* opkg_install_cmd: Cannot install package luci.
package/Makefile:64: recipe for target 'package/install' failed
make[2]: *** [package/install] Error 255

rpcd-mod-rrdnsって何？