Hi HN, I'm Tyler Flint, one of the creators of qtap.
For a while now, my team and I at Qpoint.io have been grappling with the challenge of understanding what's actually happening inside the encrypted traffic leaving our production systems. Modern apps rely heavily on third-party APIs (think payment processors, data providers, etc.), but once TLS kicks in, figuring out exactly what data is being sent, identifying PII exposure, or debugging integration issues becomes incredibly difficult without resorting to complex and often brittle solutions.
Traditional approaches like forward proxies require terminating TLS (MITM), managing certificates, and often introduce performance bottlenecks or single points of failure. Network firewalls usually operate at L3/L4 and lack payload visibility. We felt there had to be a better way.
That's why we built qtap. It's a lightweight agent that uses eBPF to tap into network traffic at the kernel level. The key idea is to hook into common TLS libraries (like OpenSSL) before encryption and after decryption. This gives us deep visibility into the actual request/response payloads of HTTPS/TLS traffic without needing to terminate the connection or manage certs. Because it leverages eBPF, the performance impact is minimal compared to traditional methods.
With qtap, we can now see exactly which external services our apps are talking to, inspect the payloads for debugging or security auditing (e.g., spotting accidental PII leaks), monitor API performance/errors for third-party dependencies, and get a much clearer picture of our egress traffic patterns.
We've found this approach really powerful for improving reliability and security posture. We've packaged qtap as a Linux Binary, Docker container, and Helm chart for deployment.
This is still evolving, but we're excited about the potential of using eBPF for this kind of deep, yet non-intrusive, visibility.
We'd love to get the HN community's feedback:
Do you face similar challenges monitoring encrypted egress traffic?
What are your thoughts on using eBPF for this compared to other methods?
Any suggestions or potential use cases we haven't considered?
To everyone building these things: Please add a disclaimer to say something like:
"This is not a vulnerability: eBPF currently requires root access to do this. Also, eBPF makes this easy but does not make it possible, as debuggers, interposers/shims, and other tools can also attach to pre-encryption points, and therefore banning eBPF (as some people want to do after seeing projects like this) would not actually improve security, but it would instead _reduce_ security as it would prevent eBPF-based security solutions from being used."
Great idea!
On an unrelated note, your work has inspired most of my career in Solaris/Illumos/Linux systems and honestly this project likely wouldn't have happened if it wasn't for all of your books/blogs/projects to help me along the way. Thank you!
Does this work for Go binaries? My understanding is that Go programs do all the encryption "in the process" so the data is encrypted before eBPF can intercept it. I'd love to be wrong about that!
We have Go support, but it is not open sourced yet. Go is a bit more complicated but we were able to get it after some cave diving in the ELF formats. To give you a little insight on how this works, because Go is statically linked, we need to pull several different offsets of the functions we are going to hook into.
We do this by scanning every version of Go that is released to find offsets in the standard library that won't change. Then when we detect a new Go process, we use an ELF scanner to find some function offsets and hook into those with uprobes. Using both of these, we have all the information we need to see Go pre-encryption content as well as attribute it to connections and processes.
Most programs do encryption without syscalls! eBPF can intercept userspace execution, which they do as mentioned in the post:
> The key idea is to hook into common TLS libraries (like OpenSSL) before encryption and after decryption
There's a similiar tool https://github.com/gojue/ecapture
Have been following this project for a while, cool stuff!
I work a bunch with vpn-like networking on Android phones and it would be cool to have a bit of info on how I might get something like working on phones. I guess its probably not your typical usecase.
Currently since the project is a VPN client, I already intercept all of the packets, I have a pcap writer and can write to files or a tcp sockets and connect wireshark to it - but it needs a bunch of complication to setup the keys so that I can see through encryption, so anything that would make that process easier would be great.
I know that arguing that SSLKEYLOGFILE is all you need will just be a different version of the rsync/dropbox comment, but I do wonder under what circumstances is one able to strace a binary and isn’t able to make it dump session keys? I read the headline and set high hopes on finding a nifty way to mitm apps on Android - alas, I’m not sure this would work there necessarily.
Isn't there already mechanisms for patching specific SSL libraries to view encrypted requests (e.g. frida)? What is the benefit of using eBPF?
To hook into OpenSSL, don't you either need dynamic linking or userspace programs to compile your hooks in? Go and many Rust and C++ binaries tend to prefer static linking, so I wonder if this solution is workable there.
Just found out about a related things: https://github.com/cle-b/httpdbg
Anyone have any experience with it?
There are many independent implementations of the same idea (given how easy it is to implement) but all suffer from similar shortcomings:
1. uprobes can be expensive and add latency (they force a context switch and copy data), especially when the hooked functions are called a lot
2. EBPF is not widely available outside of Linux, requires elevated privileges (compared to a MITM proxy that requires no privileges and works with every OS)
3. Doesn't work with JVM, Rust, any runtime that doesn't use the hooked functions
What does the usage pattern look like for this. Will I need to be root to run it, and can it run from inside a container without "real" host root?
I'm always looking for a way to make sniffing traffic from inside a container easier, and if I could attach a debug sidecar with something like an eBPF based SSL pre-master key extractor (both on incoming and outgoing requests) it starts to feel a lot like having network JTAG.
Can it output pcap files or anything similar I can import onto Wireshark or a similar tool? Haven't found anything checking the docs...
Kinda related, anyone know of something similar for Windows? This is definitely going in my toolkit, but I need something similar for Windows client traffic inspection (tls 1.2+) to get the full picture. Working with proprietary client/server coms over tls. Can use a special debug build, but requires shutting down and replacing. Need something in-sutu.
Was going to ask if it was only passive monitoring or active controlling and found https://docs.qpoint.io/appendix/qcontrol-beta
> Security enforcement: Allowing or denying traffic based on precise conditions
Very cool. What are your supported log sinks?
I'm a heavy forward proxy user. Whatever the performance hit, I don't notice it. I do notice the performance hit of HTTPS versus HTTP.
Modifying response bodies in the forward proxy is less than ideal. The proxy must wait for the full response body to be received before making modifications.
Can eBPF be any better in this regard.
With the minimal perf impact, does that mean it is not 100% guaranteed to catch all traffic? I’d think you’d have to insert yourself synchronously into the comms or allow some to get past unseen (eg when systems are heavily loaded).
I like the fact this doesn't impact performance like MITM solutions do.
Does it also work on android? Afaik ebpf is also available there.
I don't have any answers/questions, but reading through the discussion, all I can say at this point is — Super impressive guys!
Does this support other libraries besides OpenSSL? Such as BoringSSL as used in Chrome/chromium?
How easy is the set up, does this need to be deeply integrated in each step of the life-cycle?
Do you support Java? If so, how do you do this for Java?
Is there anything like this but for MacOS?
sounds like a security breach. how you ensure this does not become link in some next complex CVE?
Does this work in NixOS?
Stream any good movies lately?