How to access inaccessable portals in E3M4

[hkBattousai]

Map: E3M4 - Satan's Dark Delight

I discovered three hidden portals. They are not secret areas, so I couldn't find any documentation about them in Google.


I saved the secreenshots below. Normally these portals are not visible, I used noclip mode to make them visible.








I want to learn how to access these gates.
I will be glad if an experienced player would help me.

[Moon[Drunk]]

These portals are only for dm!
Set deathmatch to 1 and reload map.

[hkBattousai]

Thank you for the reply.
I have been playing Quake 1 for years, but I haven even once played in multiplayer mode.