These are a sub-set of the preterite-present verbs, which can be used to tell a speaker's attitude towards what he's saying. They are used with the bare infinitive of the verb, as in English, German, Dutch, and other Germanic languages.
durren - to dare to
kunnen - to know how to, be able to, can
magen - to be able to, can
moten - to have permission to, may, can
scullen - to be obligated to, ought, shall
þurfen - to need to
willen - to want to
You can see these verbs have a slightly different meaning from other Germanic languages, retaining their original meanings more clearly. This can be shown using an example:
Þu most Kwidden wreiten - you can write sentences (you have permission to write sentences)
Þu magst Kwidden wreiten - you can write sentences (you have the ability to write sentences)
Þu kannst Kwidden wreiten - you can write sentences (you know how to write sentences)
In Englisc, magen is the closest to the modern English "can, be able to" for translations.
to be strong, efficacious, to avail, prevail, be sufficient (alone); usre Friend mageþ us lytel our friends avail us little
magan to - to be good for, be the cause of, serve a purpose, have an effect; þat mæȝ to Naht that's good for nothing and 'him mæȝ to Sorge, þat to hieren' it causes him anxiety to hear that
magan wiþ - to prevail against (a disease), to be good for (some disease); Tylenol mæȝ wiþ Hefdecce Tylenol is good for headache.
magan wiþ - to have influence with (accusative); if ic mæȝ so well wiþ þic, þonn hu kannst þu mid her utgan? if I'm so influential with you, then how can you go out with her?
to be able to, can (because something is possible, or you have permission or power to)
Note: in certain dialects, this verb's infinitive is mugen, not magen. Their present plural is then mugeþ. A different dialect holds magen/mahte/gemaht as the verb, and the present as maag, maagst, mageþ