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What would happen if we didn't use TCP or UDP?

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Re: What would happen if we didn't use TCP or UDP?

#31

Post by signa11 »

valorzard wrote: post #4
pkkm wrote: post #2

You don't need to make up your own for this experiment. There's already a pretty old protocol that's far superior to TCP, but failed to get adoption because of network hardware dropping everything other than TCP and UDP. It's called SCTP.

SCTP is really cool, I first found out about it because it’s the basis for WebRTC data channels. It’s basically reliable UDP, but you can turn off the reliability if you want. Makes me wonder why QUIC exists when SCTP does…

> It’s basically reliable UDP, ...

more importantly though, it transmits multiple independent streams of message chunks in parallel.

similarity with UDP ends at message oriented nature of the protocol. closest equivalent for TCP would be MPTCP I suppose ?

Re: What would happen if we didn't use TCP or UDP?

#32

Post by bennettnate5 »

tepmoc wrote: post #24
jeroenhd wrote: post #9

Earlier quoted context omitted.

SCTP is fascinating because it's one of the backbone technologies that makes communication possible for most people on the planet (as the mobile network stack pretty much relies on it), yet it's effectively unsupported on almost every consumer device. If you want to use it, you're probably going to have to ship a userland implementation that needs privileges to open a raw network socket, because kernel implementation…

Diameter in mobile network is heavy user of SCTP, but from what I've read they moving away from diameter into HTTP calls for 6G.

For communication between carriers and some communications within a given carrier's network components, yes. Base stations all still communicate with the core network over SCTP, though.

Re: What would happen if we didn't use TCP or UDP?

#33

Post by casey2 »

It's weird to me that the definition of portable has changed from "can be moved" to "can be moved to another machine" to "can be moved to another environment" to "can be moved to another program"

We had the option to make every object addressable and we chose not to. Why keep sweating over it, just accept that software only works on the devs machine and ship that.

Re: What would happen if we didn't use TCP or UDP?

#34

Post by globular-toast »

Hawzen wrote: post #8
globular-toast wrote: post #3

What you want is a packet socket: sock_raw = socket(AF_PACKET , SOCK_RAW , htons(ETH_P_ALL)); IP networks should forward anything, but NAT is a major problem. Would be interesting to try with IPv6.

That's very interesting! I'll try out IPv6

If you want to play with packet sockets you might find my notebook useful where I was going to implement TCP/IP from scratch (well, from layer 2 up): https://github.com/georgek/notebooks/blob/master/internet.ip... I did ICMP over IP but got bored before I got to TCP, though (it's way more complicated than IP). You could drop in your custom protocol in place of ICMP.

Re: What would happen if we didn't use TCP or UDP?

#35

Post by elcritch »

ay wrote: post #11
globular-toast wrote: post #3

What you want is a packet socket: sock_raw = socket(AF_PACKET , SOCK_RAW , htons(ETH_P_ALL)); IP networks should forward anything, but NAT is a major problem. Would be interesting to try with IPv6.

To second this and expand on the reasons behind: The way the NATs (network address translators) are sharing the scarce public IPv4 addresses is by multiplexing on the transport level fields (ports in case of TCP/UDP and IDs or inner packet transport level fields in case of ICMP). Since they are unaware of your protocol, they get into a “special case mode”, which on a naive translator might consume a whole IP address…

At some point it seems like we just need to start passing laws requiring (major) internet services to provide all services on IPv6. Routers could then intercept ipv4 only devices and their dns locally and translate it to ipv6.

Still lame that in 2024 major services like Steam and Quest basically require IPv4.

I want to be able to use the internet without silly things like exhausting a network admins ipv4s.

Re: What would happen if we didn't use TCP or UDP?

#36

Post by paweladamczuk »

I always assumed any TCP/UDP packets would get captured by the OS network stack in order to be sent only to the processes listening on specific ports.

I guess this is a security feature, since a process cannot even listen on some ports without having elevated privileges. I wouldn't expect another process being able to capture all this traffic anyway. This would also require a mechanism of sending the same stream to multiple processes (TCP listeners and all-protocol listeners).

But I didn't even know it was possible to capture traffic from multiple transport layer protocols using a syscall, perhaps that syscall requires elevated privileges itself..?

Re: What would happen if we didn't use TCP or UDP?

#37

Post by Emjayen »

As someone who has implemented various transport protocols (both standard and custom) the biggest hurdle in layering atop IP will not be the gauntlet of WAN routers, surprisingly, rather consumer NAT devices.

One interesting case for a particular Netgear family of routers was that, while the traffic would survive end-to-end it was not without corruption - very specific corruption which took the form of zeroing the first 4 bytes. Given this aligns with where the src/dst ports would normally be, I suspect it was being treated as TCP/UDP albeit without the actual translation path taken.

Re: What would happen if we didn't use TCP or UDP?

#38

Post by Hawzen »

paweladamczuk wrote: post #36

I always assumed any TCP/UDP packets would get captured by the OS network stack in order to be sent only to the processes listening on specific ports. I guess this is a security feature, since a process cannot even listen on some ports without having elevated privileges. I wouldn't expect another process being able to capture all this traffic anyway. This would also require a mechanism of sending the same stream to m…

> perhaps that syscall requires elevated privileges itself..?

You are exactly right

Re: What would happen if we didn't use TCP or UDP?

#39

Post by api »

jeroenhd wrote: post #9
pkkm wrote: post #2

You don't need to make up your own for this experiment. There's already a pretty old protocol that's far superior to TCP, but failed to get adoption because of network hardware dropping everything other than TCP and UDP. It's called SCTP.

SCTP is fascinating because it's one of the backbone technologies that makes communication possible for most people on the planet (as the mobile network stack pretty much relies on it), yet it's effectively unsupported on almost every consumer device. If you want to use it, you're probably going to have to ship a userland implementation that needs privileges to open a raw network socket, because kernel implementation…

It’s too bad the original IP could not have included some kind of stronger header integrity lock to block middle boxes.

It would have forced us to adopt V6 and… my god… the network would be so much cleaner and superior in every way. Things would just have addresses, and protocol innovation at L3 would be possible.

Re: What would happen if we didn't use TCP or UDP?

#40

Post by bewo001 »

jeroenhd wrote: post #9
pkkm wrote: post #2

You don't need to make up your own for this experiment. There's already a pretty old protocol that's far superior to TCP, but failed to get adoption because of network hardware dropping everything other than TCP and UDP. It's called SCTP.

SCTP is fascinating because it's one of the backbone technologies that makes communication possible for most people on the planet (as the mobile network stack pretty much relies on it), yet it's effectively unsupported on almost every consumer device. If you want to use it, you're probably going to have to ship a userland implementation that needs privileges to open a raw network socket, because kernel implementation…

Actually, every browser supporting webrtc datachannel supports SCTP over UDP.
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