> WireGuard doesn't work over TCP.
I see this repeated in a lot of places about WireGuard but is there anything wrong with UDPTunnel (http://www.cs.columbia.edu/~lennox/udptunnel/)?
Why would one prefer this instead of WireGuard + UDPTunnel?
I see this repeated in a lot of places about WireGuard but is there anything wrong with UDPTunnel (http://www.cs.columbia.edu/~lennox/udptunnel/)?
Why would one prefer this instead of WireGuard + UDPTunnel?
But in my case, many local hospitals have free WiFi which blocks everything "suspicious", including most of UDP and many VPN-related TCP ports.
I don't know if it would be appropriate for me to comment further as I work for a middlebox provider.
Often, through some kind of employee code of conduct; think along the lines of "I agree to refrain from using my work computer for personal business." or similar. Then, if something sensitive is decrypted, the employer has some legal cover.
IP address matching: Watch raw IP layer, pass through TLS traffic to some IP range, this requires vigilance to ensure the IP range maps well to the set of sites you're OK not decrypting and doesn't include sites you want to decrypt.
SNI matching: During TLS ClientHello watch the SNI provided by the client, if it's on a whitelist, let the entire connection through. Clients aren't obliged to be honest and servers aren't required to even look at SNI, if they serve only a single site why check?
Certificate CN/ SAN matching: Stall during TLS ClientHello, wait for the responding ServerHello and Certificate from the server, and examine the certificate for a hostname, check if it's whitelisted. Otherwise, decrypt the connection.
That last technique is very popular, and real middlebox companies (e.g. Cisco) have argued that since it doesn't work in TLS 1.3 (the Certificate message is encrypted so they can't read it) this is a significant security-relevant change. In the rant below I will show how to bypass this "security" check mostly because it is useless, companies selling it have been selling snake oil. Either they're too stupid to know it doesn't work or they assume their customers are too stupid, either way why would you deal with a "security" company like that?
1. Certificate contains only public documents, one or more X.509 certificates. Bad guys can get Google's certificate, or that of a bank, STI clinic or government regulator by simply connecting to those outfits and gathering the certificate.
2. The legitimate _client_ (e.g. your web browser) will need proof that the web site knows the Private Key corresponding to the public key in the certificate, but that proof is encrypted, either implicitly (RSA key exchange sends the session keys encrypted with the public key) or explicitly (modern cipher suites present an encrypted public key proof of ownership for the session) and so a middlebox can't see it except by interposing and decrypting everything.
3. Thus a "rogue" client can just connect to a "rogue" TLS endpoint and send SNI for www.google.com [pick any whitelisted hostname here], the server sends back a Certificate message for www.google.com and then the client just ignores the public key inside that certificate and presses on using a defined public key for the rogue server.
The middlebox cannot detect this happening, regardless of whether TLS 1.3 or earlier are used, it works the same and the "security" features in the middlebox don't prevent it.
Again, middlebox vendors have been _told_ about this, they either aren't bright enough to understand it (so you should not trust them) or they are lying to customers in the hope the customers don't understand it (so you should not trust them) and either way the result is the same.
Can't the middlebox just connect to the same endpoint, verify the certificate itself by checking that it is signed by a proper CA, and then, if it is not, drop the connection?
But the middlebox can, indeed, verify that when it connects to this same (IP, port) pair that endpoint is able to prove it's the real thing. I have never seen one that does this, and it won't prove anything about other connections, since our "rogue" TLS server can proxy everything to the real whitelisted server and that will pass, but yes you could do that.
You can invent arbitrarily sophisticated schemes and counter-schemes in this space. The 32 bytes of ClientHello random in particular mean you can never tell whether the client is signalling to the server or not if you even sometimes choose not to interpose.
There will no doubt be a way to get around your networks propensity to block traffic that looks encrypted, though we are getting very specific to that circumstance in order to do so. Perhaps using actual valid HTTP protocol on port 80 to send and receive data via POST requests (polling for receive if there is nothing to send) would be sufficient, though not efficient. If not then you could try hide the encrypted traffic inside what looks like plain text, maybe sending book passages and flipping between upper and lower case to represent 1 & 0 bits... Though of course any human looking at packets that are part of the stream are going to see that you are trying to hide something, though that would be a problem with all these techniques.
But really, you don't have internet access at that point, so you shouldn't expect internet software to work.
The previous commenter was pointing out that you don’t need your VPN to support TCP in order to tunnel it over TCP, since that is exactly what UDP Tunnel is designed to do.
It allows you to tunnel UDP over a fake, non-lossless TCP connection. That is, it wraps packets in TCP headers to make them look like TCP to firewalls, but it doesn't actually implement TCP; instead, each "TCP" packet corresponds to one UDP packet, and it makes no attempt to resend dropped packets. This way you avoid the problems with TCP-over-TCP.
In FakeTCP header mode,udp2raw simulates 3-way handshake while establishing a connection,simulates seq and ack_seq while data transferring.
--seq-mode <number> seq increase mode for faketcp:
0:static header,do not increase seq and ack_seq
1:increase seq for every packet,simply ack last seq
2:increase seq randomly, about every 3 packets,simply ack last seq
3:simulate an almost real seq/ack procedure(default)
4:similiar to 3,but do not consider TCP Option Window_Scale,
maybe useful when firewall doesnt support TCP Option
The FakeTCP mode does not behave 100% like a real tcp connection. ISPs may be able to distinguish the simulated tcp traffic from the real TCP traffic (though it's costly). seq-mode can help you change the seq increase behavior slightly. If you experience connection problems, try to change the value.
The strange DNS and loss spikes however are not. If they aren't documented in the project, could you elaborate on these issues?
Though it would probably be wise at that point to make it congestion control aware, since TCP over TCP has some issues which are not considered solved.