Show HN: Using eBPF to see through encryption without a proxy

[tylerflint]

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?

Happy to answer any questions!

[brendangregg]

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."

[tylerflint]

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!

[bbkane]

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!

[tylerflint]

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.

[lights0123]

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

[zxilly]

There's a similiar tool https://github.com/gojue/ecapture

[dilyevsky]

Grafana's Beyla also basically works the same way https://github.com/grafana/beyla

[ebb_earl_co]

I was just about to ask what the difference is here with `ecapture`

[compscidr]

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.

[PcChip]

I'm curious what your product does

I've seen that type of behavior for apps that inject ads and add affiliate marketing links

[eptcyka]

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.

[formerly_proven]

Mostly that SSLKEYLOGFILE has only been an (disabled by default) OpenSSL feature for a few weeks (literally), apart from that it's something implemented by some other libraries (notably libcurl) on top. But it's very far from "just set this env var and the keys will pop out of any app using TLS".

[delusional]

The big usecase for me would be if you could attach the trace after starting the binary. The idea of coming into a production system that's behaving unexpectedly and getting a network sniff without having to fiddle with certificates is very attractive.

There's an alternative implementation where SSLKEYLOGFILE is more "dynamic" and permits being toggled on an off during runtime, but that doesn't currently exist.

[linsomniac]

My big use case is watching on the SERVER side, my coworkers will be asking me to help them debug something and I just want to see the HTTP plaintext, I don't really want to try running Apache under SSLKEYLOGFILE or something, I just want to see the data. ;-)

[worldsavior]

Isn't there already mechanisms for patching specific SSL libraries to view encrypted requests (e.g. frida)? What is the benefit of using eBPF?

[tylerflint]

The main benefit is complete coverage. In production systems there are many different workloads with many different binaries, each with different build processes. Leveraging eBPF enables seeing everything on a system without having to adjust the build pipeline.

[pclmulqdq]

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.

[tylerflint]

Great point! Yes it supports both scenarios. Qtap scans the binary ELF (curl, rust, etc) and looks for the TLS symbols. If they were statically compiled the eBPF probes will be attached directly to the binary, if dynamically linked the probes will be attached to the symbols in the library (.so).

[kristopolous]

Just found out about a related things: https://github.com/cle-b/httpdbg

Anyone have any experience with it?

[markasoftware]

this looks like it hooks into python libs, not all openssl traffic system-wide.

[armitron]

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

[jonfriesen]

These are all great callouts. We've worked hard to address some of them, some are future endeavours.

To address your points:

1. In our testing, uprobes add a statistically insignificant amount of latency and in comparison to a MITM proxies it's nearly identical to native.

2. True, we're focused on Linux right now. I'm looking forward to exploring Microsoft's eBPF implementation and exploring how we can support the Windows ecosystem.

3. You're right that the technique we are using for OpenSSL will not work for other runtimes. That said, there are other techniques that we've implemented in our Pro offering for the JVM, Go, and NodeJS. Rust is in the works!

[delusional]

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.

[jonfriesen]

Qtap does require root privileges to function as it uses eBPF to hook into kernel and userspace program functions. The good news is it can also be run within a container.

There are some important flags when spinning it up in docker: `--privileged`, `--cap-add CAP_BPF`, `--cap-add CAP_SYS_ADMIN`, and `--pid=host`. These provide access to load eBPF programs, and monitor traffic.

Many deployments use Kubernetes daemonsets where Qtap runs in a container, but monitors all of the traffic on the node. The Qpoint paid offering comes with a Control Plane that produces context specific dashboards so seeing what's happening from a specific container, or pod namespace can provide a lot of insights into your deployments.

[tecleandor]

Can it output pcap files or anything similar I can import onto Wireshark or a similar tool? Haven't found anything checking the docs...

[jonfriesen]

As of today, we don't output pcap or har files though these are additions I'd like to make in the future, they aren't currently on our near term roadmap.

[Severian]

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.

[mrbluecoat]

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?

[jonfriesen]

Thanks! We're really excited about Qcontrol and what it will be able to provide! The rules in that doc are powered by our Rulekit project https://github.com/qpoint-io/rulekit if you're curious about seeing more.

As far as log sinks, we have stdout right now. We have been working on Fluentbit and will eventually add a bunch more. If you have a request, drop them here!

We also have a services concept which support an "event store" and "object store", where the object store handles artifacts that may contain sensitive data and don't need to be indexed for search/aggregation (this is an S3 compliant store). The event store handles all of the events from connection audit logs (these cover the ip protocol level) to individual http request/response pairs. The event store is a custom API we use and need to write some proper documentation for, stay tuned!

[1vuio0pswjnm7]

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.

[hamburglar]

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).

[0nethacker1]

I like the fact this doesn't impact performance like MITM solutions do.

[jonfriesen]

That was one of our biggest motivators when dreaming up Qtap.

How can we remove the impact that proxies have on connections, AND see the content without having to manage a custom certificate authority, AND not have to instrument all of our code.

[dahateb]

Does it also work on android? Afaik ebpf is also available there.

[jonfriesen]

Not today, maybe one day!

Edit: Another user posted a link to https://github.com/gojue/ecapture which looks like it supports android and has some overlapping functionality.

[sunbum]

Look into HTTP Toolit for android (not affiliated with it at all, it's just that cool a tool)

[octobereleven]

I don't have any answers/questions, but reading through the discussion, all I can say at this point is — Super impressive guys!

[ranger_danger]

Does this support other libraries besides OpenSSL? Such as BoringSSL as used in Chrome/chromium?

[adampk]

How easy is the set up, does this need to be deeply integrated in each step of the life-cycle?

[tylerflint]

Just run the qtap agent on whatever Linux machine has apps running on it and it will see everything through the kernel vs eBPF.

You can customize config and/or integrate with existing observability pipelines, but initially you just need to turn it on for it to work. No app instrumentation required.

[plicense]

Do you support Java? If so, how do you do this for Java?

[tylerflint]

Java is supported, but currently in the pro version. Since JavaSSL is implemented in Java code, which runs in the Java VM and not exported as static symbols that can be uprobe'd, there is a bit more involved to generate a bridge between the JVM bytecode and static symbols that can be probed.

[onnimonni]

Is there anything like this but for MacOS?

[jonfriesen]

I think the closest is an app with a full GUI called LittleSnitch. It's pretty impressive.

https://www.obdev.at/products/littlesnitch/index.html

[nikolayasdf123]

sounds like a security breach. how you ensure this does not become link in some next complex CVE?

[jonfriesen]

This is a great point, and Qtap itself does need to be used with care. The company behind Qtap (Qpoint.io) provides full inventory and alerting for this sort of scenario.

That said, the eBPF verifier has robust security guarantees and runs on every load. So arbitrary mem access for example isn't possible. Qtap runs exclusively on your nodes, so you control what it captures and where that data goes. Our paid offering provides more functionality with a Control Plane solutions that provides dashboards, alerting, and live config updates. However, all sensitive information, like captured http bodies, are uploaded to a S3 compliant bucket that you control. This could be S3, Minio, or anything else that supports the S3 API. We never see this information.

It's intentionally designed for deployment within your infra and abides by the security policies you set within your org.

[mberning]

My first thought was this is cool. My second thought was that this is going to be impossible to securely manage and administer.

[CMCDragonkai]

Does this work in NixOS?

[jonfriesen]

Yes, since NixOS runs on a standard Linux kernel, Qtap will work. I realized that we weren't scanning the nix store for shared libs (eg. OpenSSL) and added that this morning.

[otterley]

Out of curiosity, do you use NixOS in production? If so, how large of an installation do you have?

[jakedata]

Stream any good movies lately?