In the process of changing my OpenVPN setup, but need to find out what UDP port often gets the most traffic.
The reason for UDP is to avoid some of the latency and speed losses that TCP suffers, due to the constant negotiations. Since OpenVPN already does it, there is no point in it being done for a second time by using the TCP protocol.
Tried UDP 443, but since that isn’t actually a common network port, it is blocked on quite a few networks that I want to use my VPN on, so I need to find another, common UDP port which handles high amounts of traffic.
I know UDP 1935 is used for Flash, so I was thinking of potentially that port, since it’s (probably) unlikely to be blocked on most networks, since it would break a lot of things (I would think, don’t know much about it)
Commonly used for SIP (VOIP) traffic and usually has real time prioritization under QoS scenarios.
But keep in mind that Many firewalls do cursory packet inspection.
So Traffic on Port 53 is sometimes checked as DNS and dropped if it is invalid DNS traffic. Same goes for VoIP, but it really depends on if the network admin is doing their job right or not.
Other ports you can commonly abuse are:
1434 ( Old MS SQL)
500 CISCO VPN (IPSec over UDP)
4500 Also CISCO (IPSec Tunnel)
10’000 CISCO NAT ( TCP& UDP Depends really)
Other ports that are also potentially rife are
49174 (Old XSAN stuff)
1719 (H323 RAS)
2326-2485 (SIP UDP Video data Ports)
Really most of these should drop invalid UDP packets if your behind a good well configured firewall. But you know how things are…
No, TCP is terrible. Only use it if everything else is blocked. It’s not just latency, it’s the inconsistent performance from retransmitting packets that kills you.