Brad Fitzpatrick
b0b1f0f566
This is the output of the new misc/bumpdeps tool (#21325) run with --exclude-newer-than-days=7, which asks proxy.golang.org for the newest version of every direct dependency, ignoring releases younger than a week in favor of the newest older one, and runs a single go get. gvisor tracks its "go" branch, wireguard-go its "tailscale" branch, and golang-x-crypto its "main" branch (the proxy's @latest for it is a stray v0.91.0 tag from 2024 that predates our acme fork changes). Indirect deps only moved as far as MVS pulled them. The week-long cooldown held back gvisor, the gokrazy modules, chromedp/cdproto, and hashicorp/raft-boltdb/v2, whose only newer versions are days old; they'll come along next time. Several upstream changes needed small fixes: nfpm's PrepareForPackager takes a modification time now (a zero time keeps the old behavior of using the source file's mtime), esbuild's ServeOptions.Port became an int while ServeResult.Host became a Hosts slice, client-go's EventRecorder.Eventf is now recognized by vet as a printf wrapper (so the k8s-operator calls that passed a preformatted message switch to Event), google/nftables v0.3.0 reads back the kernel's NF_NAT_RANGE_PROTO_SPECIFIED flag into a new expr.NAT.Specified field (so the port map DNAT rule now sets it too or findRule never matches the rule it just added), and staticcheck v0.8.1 knows encoding/json/v2's embed tag option, so the two SA5008 suppressions for it are gone. Two tests assumed old library behavior. client-go's fake clientset now replays existing objects when a watch starts, as a real apiserver does, so the k8s-proxy config test must tolerate the loader ignoring that no-op event before the real reload arrives. fyne.io/systray moved its dbusmenu object path and answers the first GetLayout with depth 1, so the systray test now finds the menu via the item's Menu property and polls until the submenu entries appear. Then make tidy, make updatedeps, and make kube-generate-all (the controller-gen bump to v0.22.0 changes doc strings, stops listing top-level metadata as required, and crd-ref-docs now marks optional fields). Updates #8043 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com> Change-Id: I3f9a2c6e8b1d4705a9e2c7b8d1f4e6a0c2b5d8e3
DERP
This is the code for the Tailscale DERP server.
In general, you should not need to or want to run this code. The overwhelming majority of Tailscale users (both individuals and companies) do not.
In the happy path, Tailscale establishes direct connections between peers and data plane traffic flows directly between them, without using DERP for more than acting as a low bandwidth side channel to bootstrap the NAT traversal. If you find yourself wanting DERP for more bandwidth, the real problem is usually the network configuration of your Tailscale node(s), making sure that Tailscale can get direction connections via some mechanism.
If you've decided or been advised to run your own derper, then read on.
Caveats
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Node sharing and other cross-Tailnet features don't work when using custom DERP servers.
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DERP servers only see encrypted WireGuard packets and thus are not useful for network-level debugging.
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The Tailscale control plane does certain geo-level steering features and optimizations that are not available when using custom DERP servers.
Guide to running cmd/derper
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You must build and update the
cmd/derperbinary yourself. There are no packages. Usego install tailscale.com/cmd/derper@latestwith the latest version of Go. You should update this binary approximately as regularly as you update Tailscale nodes. If using--verify-clients, thederperbinary andtailscaledbinary on the machine must be built from the same git revision. (It might work otherwise, but they're developed and only tested together.) -
The DERP protocol does a protocol switch inside TLS from HTTP to a custom bidirectional binary protocol. It is thus incompatible with many HTTP proxies. Do not put
derperbehind another HTTP proxy. -
The
tailscaledclient does its own selection of the fastest/nearest DERP server based on latency measurements. Do not putderperbehind a global load balancer. -
DERP servers should ideally have both a static IPv4 and static IPv6 address. Both of those should be listed in the DERP map so the client doesn't need to rely on its DNS which might be broken and dependent on DERP to get back up.
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A DERP server should not share an IP address with any other DERP server.
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Avoid having multiple DERP nodes in a region. If you must, they all need to be meshed with each other and monitored. Having two one-node "regions" in the same datacenter is usually easier and more reliable than meshing, at the cost of more required connections from clients in some cases. If your clients aren't mobile (battery constrained), one node regions are definitely preferred. If you really need multiple nodes in a region for HA reasons, two is sufficient.
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Monitor your DERP servers with
cmd/derpprobe. -
If using
--verify-clients, atailscaledmust be running alongside thederper, and all clients must be visible to the derper tailscaled in the ACL. -
If using
--verify-clients, atailscaledmust also be running alongside yourderpprobe, andderpprobeneeds to use--derp-map=local. -
The firewall on the
derpershould permit TCP ports 80 and 443 and UDP port 3478. -
Only LetsEncrypt certs are rotated automatically. Other cert updates require a restart.
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Don't use a firewall in front of
derperthat suppressesRSTs upon receiving traffic to a dead or unknown connection. -
Don't rate-limit UDP STUN packets.
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Don't rate-limit outbound TCP traffic (only inbound).
Diagnostics
This is not a complete guide on DERP diagnostics.
Running your own DERP services requires exeprtise in multi-layer network and application diagnostics. As the DERP runs multiple protocols at multiple layers and is not a regular HTTP(s) server you will need expertise in correlative analysis to diagnose the most tricky problems. There is no "plain text" or "open" mode of operation for DERP.
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The debug handler is accessible at URL path
/debug/. It is only accessible over localhost or from a Tailscale IP address. -
Go pprof can be accessed via the debug handler at
/debug/pprof/ -
Prometheus compatible metrics can be gathered from the debug handler at
/debug/varz. -
cmd/stuncin the Tailscale repository provides a basic tool for diagnosing issues with STUN. -
cmd/derpprobeprovides a service for monitoring DERP cluster health. -
tailscale debug derpandtailscale netcheckprovide additional client driven diagnostic information for DERP communications. -
Tailscale logs may provide insight for certain problems, such as if DERPs are unreachable or peers are regularly not reachable in their DERP home regions. There are many possible misconfiguration causes for these problems, but regular log entries are a good first indicator that there is a problem.