nodebb-plugin-import-phpbb
A phpBB2 to NodeBB exporter based on nodebb-plugin-import-ubb by Aziz Khoury
Use this to import data into NodeBB using nodebb-plugin-import.
Have a look at the original UBB migrator for detailed instructions on how to use this importer.
You may want to check out the bbcode-to-markdown plugin as well.