c5abbcd4b4
This is a fun one. Right now, when a client is connecting through a subnet router, here's roughly what happens: 1. The client initiates a connection to an IP address behind a subnet router, and sends a TCP SYN 2. The subnet router gets the SYN packet from netstack, and after running through acceptTCP, starts DialContext-ing the destination IP, without accepting the connection¹ 3. The client retransmits the SYN packet a few times while the dial is in progress, until either... 4. The subnet router successfully establishes a connection to the destination IP and sends the SYN-ACK back to the client, or... 5. The subnet router times out and sends a RST to the client. 6. If the connection was successful, the client ACKs the SYN-ACK it received, and traffic starts flowing As a result, the notification code in forwardTCP never notices when a new connection attempt is aborted, and it will wait until either the connection is established, or until the OS-level connection timeout is reached and it aborts. To mitigate this, add a per-client limit on how many in-flight TCP forwarding connections can be in-progress; after this, clients will see a similar behaviour to the global limit, where new connection attempts are aborted instead of waiting. This prevents a single misbehaving client from blocking all other clients of a subnet router by ensuring that it doesn't starve the global limiter. Also, bump the global limit again to a higher value. ¹ We can't accept the connection before establishing a connection to the remote server since otherwise we'd be opening the connection and then immediately closing it, which breaks a bunch of stuff; see #5503 for more details. Updates tailscale/corp#12184 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I76e7008ddd497303d75d473f534e32309c8a5144 |
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README.md
Tailscale
Private WireGuard® networks made easy
Overview
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
Other Tailscale repos of note:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.
Using
We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.
Other clients
The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.
Building
We always require the latest Go release, currently Go 1.22. (While we build releases with our Go fork, its use is not required.)
go install tailscale.com/cmd/tailscale{,d}
If you're packaging Tailscale for distribution, use build_dist.sh
instead, to burn commit IDs and version info into the binaries:
./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled
If your distro has conventions that preclude the use of
build_dist.sh, please do the equivalent of what it does in your
distro's way, so that bug reports contain useful version information.
Bugs
Please file any issues about this code or the hosted service on the issue tracker.
Contributing
PRs welcome! But please file bugs. Commit messages should reference bugs.
We require Developer Certificate of
Origin
Signed-off-by lines in commits.
See git log for our commit message style. It's basically the same as
Go's style.
About Us
Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.