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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?

#111

Post by netbsdusers »

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…

DHCP services require this ability to receive and send UDP packets on raw sockets, barring a few advanced systems like Solaris that provide them with necessary facilities. Usually they install a BPF module on the socket to filter out uninteresting packets.

https://kb.isc.org/docs/aa-00379

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

#113

Post by dakra137 »

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.

TCP would be fine if it had the concept of message, in addition to stream. The sender sends a message. It flows to the recipient. The recipient program can specify that a receive receives the entire message, no more and no less, as long as the application's target input buffer is large enough.

SCTP does this.

A shim on top of TCP socket receive could also do this also, as long as there is a convention to prefix each message with a length field, say 16 bits, with the MSB indicating that the message is incomplete and is continued in the next length delimited segment.

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

#114

Post by bcrl »

nickburns wrote: post #95
tsimionescu wrote: post #91

Earlier quoted context omitted.

> That DoH is specced to operate over port TCP/443 makes it no more or less efficacious than DoT over TCP/853 with regard to avoiding censorship. I.e., they're both encrypted. Of course there is. Blocking all traffic with destination port 443 is virtually impossible. Conversely, blocking port 853 is trivial, and it forces all clients to either not resolve DNS, or downgrade to un-encrypted DNS. Of course, if DoH had n…

You've sidestepped my point and merely reiterated yours. Both DoH and DoT achieve actual concealment (and therefore privacy and censorship avoidance) through encryption. That one is more obscure than the other doesn't change the fact that the whole point of both protocols is encrypted DNS queries, not obscured DNS queries. And again, if I'm the network operator and a host can obscure/obfuscate its DNS queries, then I…

Some ISPs do run DNS servers to improve performance for their customers, not to snoop on them. My company is one of them. Being able to answer DNS queries in <1ms is far superior to the 8-25ms of latency over the transport network to the nearest peering point, especially when most clients are hitting the same names over and over. It's not like any of the public DNS servers are more trustworthy.

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

#115

Post by graealex »

hylaride wrote: post #52
api wrote: post #39

Earlier quoted context omitted.

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.

I'd like to agree with you, but IPv6 had such a classic case of suffocation by committee during its birth that I doubt it would have been pushed by such a situation. IPSec was mandated in the original IPv6 RFC, for god's sake. That alone delayed a lot of work in implementing it as crypto code needed to be integrated into kernels, which was not common in those days. That's to say nothing about the fact that IPSec is l…

It's funny that you mention IPSec, since that would have made most of the application-level encryption we see today obsolete. They did have good intentions, and if it was widely accepted, it would have meant that barely any applications would have had to deal with the details of encryption, including the ever-looming possibility of doing it wrong (doing encryption right is hard!).

Now we have a slew of protocols that either implement TLS, or roll their own custom thing, or have X-over-HTTPS protocols, including SSTP and DoH.

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

#116

Post by hylaride »

graealex wrote: post #115
hylaride wrote: post #52

Earlier quoted context omitted.

I'd like to agree with you, but IPv6 had such a classic case of suffocation by committee during its birth that I doubt it would have been pushed by such a situation. IPSec was mandated in the original IPv6 RFC, for god's sake. That alone delayed a lot of work in implementing it as crypto code needed to be integrated into kernels, which was not common in those days. That's to say nothing about the fact that IPSec is l…

It's funny that you mention IPSec, since that would have made most of the application-level encryption we see today obsolete. They did have good intentions, and if it was widely accepted, it would have meant that barely any applications would have had to deal with the details of encryption, including the ever-looming possibility of doing it wrong (doing encryption right is hard!). Now we have a slew of protocols that…

IPSec was far too complicated, loosely defined, and over-engineered to have ever been widely accepted. Any host verification would need to involve application level verification anyways to make sure the other end is who you expect. So your browser would need to verify the encrypted tunnel is in face connected to google, or whoever. There’s a reason SSL/TLS is done at the application level.
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