Tracing TCP

[mjallday]

Tracing TCP

[yurishkuro]

Are you sure referring to this as "TCP Header" is accurate? Afaik TCP Header structure is predefined by the TCP spec. What PROXY protocol seems to be doing is sending a specialized payload upon establishing a connection - a mechanism that is not fully transparent to the receiver, i.e. the receiver needs to actually support that or be confused by the incoming data stream. Please correct me if I am wrong, as I only briefly skimmed the PROXY spec.

Another issue is that tracing headers need to be sent on per-request basis, not just upon establishing the TCP connection.

[mjallday]

Are you sure referring to this as "TCP Header" is accurate?

probably not, that's just my attempt at using a familiar nomenclature. in the above link it's described as

"header" or "PROXY protocol header" is the block of connection information
the connection initiator prepends at the beginning of a connection, which
makes it the sender from the protocol point of view.

I'm not sure what term would work better but hopefully this conveys the concept accurately. happy to edit the description to something that's more technically accurate if there's a suggestion available.

i.e. the receiver needs to actually support that or be confused by the incoming data stream

this is correct. the receiver of the tcp stream needs to be aware of how to parse this.

Another issue is that tracing headers need to be sent on per-request basis, not just upon establishing the TCP connection.

yeah, I raised this as a question in the original post too. for our company this is an acceptable tradeoff. using http connect tunnels as an example, we could establish the tcp trace id as the parent trace id for the tunnel and then the requests within that tunnel could be treated separately or as children.

I definitely understand there's some issues to solve or trade offs to accept to make it work, do you know of any other strategies for achieving this? We deal mostly with encrypted data and a lot of non-http payloads so parsing the payload and injecting a header isn't always an option.

[yurishkuro]

You can try it, but I don't think the mechanism is generic enough, especially given one-per-connection limitation that's not going to work for many users.