Who is the Porter and what is his speech?

The Porter in Macbeth appears in Act 2, scene 3. His speech is below:

PORTER

Here’s a knocking indeed! If a man were porter of hell-gate, he should have old turning the key. Knock, knock, knock! Who’s there, i' th' name of Beelzebub? Here’s a farmer that hanged himself on the expectation of plenty. Come in time, have napkins enough about you, here you’ll sweat for ’t. Knock, knock! Who’s there, in th' other devil’s name? Faith, here’s an equivocator that could swear in both the scales against either scale, who committed treason enough for God’s sake, yet could not equivocate to heaven. O, come in, equivocator. Knock, knock, knock! Who’s there? Faith, here’s an English tailor come hither for stealing out of a French hose. Come in, tailor. Here you may roast your goose. Knock, knock! Never at quiet. What are you? But this place is too cold for hell. I’ll devil-porter it no further. I had thought to have let in some of all professions that go the primrose way to the everlasting bonfire. Anon, anon! I pray you, remember the porter. (II.iii.1-20)

The Porter permanently exits the stage shortly after Macbeth arrives later in the scene and so this monologue is what he is most remembered for in the play. In the monologue, the porter makes many sexual euphemisms, which signals that his character is bawdy. "Roast your goose," for instance, is in reference to a prostitute, as "goose" was slang for prostitute. A "French hose" can also be read as a sexual euphemism. More prominent than anything, however, is the Porter's drunkenness. The Porter is exceptionally drunk, and this becomes clear during his interactions with Macduff and Lennox. In regards to tone, the Porter is also a desired break from the tragedy that bookends this scene, as Duncan's murder is announced after this scene.