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UDP is treated fairly well by firewalls... at least compared to SCTP for example. QUIC/HTTP3 are UDP-based and even though there's usually a TCP/HTTP2 fallback
by bonzini 6y ago
UDP is treated fairly well by firewalls... at least compared to SCTP for example. QUIC/HTTP3 are UDP-based and even though there's usually a TCP/HTTP2 fallback they fare reasonably well.
- iso1631 6y agoI have various boxes which we send out to venues, on the whole outgoing connections are fine, but sometimes you get some really restrictive policies. I've had stuff that MITMs TCP/443, completely blocks UDP, etc. My devices tend to try to connect back via * UDP port 443, sometimes works * an sstp vpn * SSH to tcp/$highnumber, sometimes they blck/MITM port 80, 443, but leave the standard * DNS I can't think of a time that one of them didn't through.
- lxgr 6y agoIt does make it through many firewalls these days, yes. But all implementations I know use a much shorter timeout/keepalive period for UDP than they use for TCP because of firewalls/NATs. (I think the RFCs even recommend something like 300 seconds for TCP, but only 30 for UDP as a default?) This has pretty significant implications on power consumption for mobile devices.