Link to thread:
https://archive.4plebs.org/pol/thread/223377277

Text of warning (first two posts in thread):

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Friendly Advice from Antifa for Unwanted Portland Guests
August 19th, 2019

1) Look at Chris Cantwell, anyone involved in violence at Charlotte. Police don't care? We NEVER stop hunting.
2) Show your face, we'll get a name. A hundred people you will never find will have Google Alerts on your name for the next five years. Trailing alerts will last until the end of your life.
3) You will be fired. You will get a divorce, your wife's lawyer will get a file on you and your activities - judge will stick it to you. You will be unemployable. Hopefully you like to mow lawns door to door.
4) We have eyes everywhere. Cameras, seen and unseen. And the thing you didn't know? We have more than one license plate reader vehicle. You have anything resembling white supremacy visible on your vehicle, you're already caught.

5) Please, bring a cell phone with you to capture the glorious battle. Pay no attention to weird random base stations that don't actually provide you any service.
6) This is our city. It has our network. The network that we don't own, some of us get paid to operate and secure. You get on free wifi? Really good speed? You ever wonder who maintains that stuff? Ever wonder who might be a little further away than the averag hot spot?
7) You park a vehicle, you gonna park it in a group with someone to keep an eye on them? Just one guy? Obvious WN guy, all alone? We like that. Better to disperse.
8) You find a $25 burner phone well wrapped and duct taped under your truck? Well, shit happens. It's not Soros money, but it sure works.
9) All of this is entirely legal. Feel free to ask an attorney. We've played this game in Baghdad, in Kabul, and a thousand other places you've never heard mentioned. If you don't want to be treated like ISIS, don't act like ISIS.

In summary:
1) Do not come to my city.
2) If you come, do not fly any neo-Nazi/White Supremacist crap on your vehicle. Or shirt. Or flags. Or helmet. Or shield. Do not bring a cell phone. Do not use free WiFi. Do not bring a video recording device, because if you "lose" it in some form or fashion, it will almost definitely be used to identify everyone around you.
3) Do not be alone. But, we will notice when you are in groups that are too big, or look like they may be up to no good. The license plate readers will get you, there are eyes everywhere, cameras, both seen and unseen. We have access to all of them.
4) All that brave talk about "onions-boy" antifa? U.S. Army/Marines are 30% black/Hispanic. That's 150k with combat infantry badges and 750k who've been deployed somewhere that counter-terror is a daily grind.
5) Antifascism is self-defense. If you choose to attack, prepare for the consequences.
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The posts were met with wide derisions from other 4chan anons.