☠️Contemporaneous Open

Author: @Kkevsterrr#7469

What should we do?

we want to give you the flag, we really do. just give us a TCP HTTP server to send it to, and we'll make a POST request with all the deets you need! we've just got a firewall issue on our side and we're dropping certain important packets (specifically, any inbound SYN+ACK packet is dropped). Shouldn't be a problem for a networking pro like you, though - just make a TCP server that doesn't need to send those!

so glad you're here! i would love to give you the flag. just give me the IP address that's running an HTTP server, and I'll shoot you the flag immediately.
oh one snag, we've got some firewall issues on our side, and some important packets are getting dropped. shouldn't be a problem for you, though.
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What did we do!