reverst: HTTP reverse tunnels over QUIC
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Reverst is a (load-balanced) reverse-tunnel server and Go server-client library built on QUIC and HTTP/3.
- Go Powered: Written in Go using quic-go
- Compatible: The Go
client
package is built on net/http
standard-library abstractions
- Load-balanced: Run multiple instances of your services behind the same tunnel
- Performant: Built on top of QUIC and HTTP/3
Use-case
Reverst is for exposing services on the public internet from within restrictive networks (e.g. behind NAT gateways).
The tunnel binary is intended to be deployed on the public internet.
Client servers then dial out to the tunnels and register themselves on target tunnel groups.
A tunnel group is a load-balanced set of client-servers, which is exposed through the reverst tunnel HTTP interface.
Client
Install
go get go.flipt.io/reverst/client
Building
go install ./client/...
Server
Building
go install ./cmd/...
Testing
Reverst uses Dagger to setup and run an integration test suite.
dagger call test --source=.
The test suite sets up a tunnel, registers a server-client to the tunnel and then requests the service through the tunnels HTTP interface.
Running
The following walks through experimenting with the ./examples/simple server example.
This directory contains a number of things needed to stand up reverst and a registering client server:
- The example service in ./examples/simple/main.go.
- Simple self-signed TLS private key and certificate.
- A tunnel-groups file for routing decisions.
Running reverst
The following runs the tunnel server with:
- The QUIC tunnel listener on
127.0.0.1:7171
- The HTTP serving listener on
127.0.0.1:8181
- Logging with
debug
level
- A TLS server-name of
flipt.dev.local
- Some tunnel group definitions with a single tunnel group
- The group has the name
flipt.dev.local
- The group is reachable under the same host name
- The group requires basic username and password authentication
- The dummy TLS certificates
go run ./cmd/reverst/... -l debug \
-n flipt.dev.local \
-g examples/simple/group.yml \
-k examples/simple/server.key \
-c examples/simple/server.crt
Running example server
Now you can run the example server.
This is a simple HTTP server that responds to all requests with PONG
.
It is setup to use the server client to register as a listener on the tunnel.
go run ./examples/simple/main.go --username user --password pass
Making requests
You can now curl the tunnel and requests will be forward all the way through to the example server.
Be sure to include the Host
header, as this is used to route requests to the respective tunnel-group.
curl -H 'Host: flipt.dev.local' 127.0.0.1:8181/fo
Usage and Configuration
Command-Line Flags and Environment Variables
The following flags can be used to configure a running instance of the reverst
server.
➜ reverst -h
COMMAND
reverst
USAGE
reverst [FLAGS]
FLAGS
-l, --log LEVEL debug, info, warn or error (default: INFO)
-a, --tunnel-address STRING address for accepting tunnelling quic connections (default: 127.0.0.1:7171)
-s, --http-address STRING address for serving HTTP requests (default: 0.0.0.0:8181)
-n, --server-name STRING server name used to identify tunnel via TLS (required)
-k, --private-key-path STRING path to TLS private key PEM file (required)
-c, --certificate-path STRING path to TLS certificate PEM file (required)
-g, --tunnel-groups STRING path to file or k8s configmap identifier (default: groups.yml)
-w, --watch-groups watch tunnel groups sources for updates
--management-address STRING HTTP address for management API
--max-idle-timeout DURATION maximum time a connection can be idle (default: 1m0s)
--keep-alive-period DURATION period between keep-alive events (default: 30s)
The long form names of each flag can also be referenced as environment variable names.
To do so, prefix them with REVERST_
, replace each -
with _
and uppercase the letters.
For example, --tunnel-address
becomes REVERST_TUNNEL_ADDRESS
.
Tunnel Groups Configuration YAML
configuring
Currently, the tunnel groups configuration can be sourced from two different locations types (file
and k8s
).
Both tunnel group sources support watching sources for changes over time (see -w
flag).
- Local filesystem (
file://[path]
)
The standard and simplest method is to point reverst at your configuration YAML file on your machine via its path.
reverst -g path/to/configuration.yml
// alternatively:
reverst -g file:///path/to/configuration.yml
- Kubernetes ConfigMap
k8s://configmap/[namespace]/[name]/[key]
Alternatively, you can configure reverst to connect to a Kubernetes API server and fetch / watch configuration from.
reverst -g k8s://configmap/default/tunnelconfig/groups.yml
defining
The reverst server take a path to a YAML encoded file, which identifies the tunnel groups to be hosted.
A tunnel group is a load-balancer on which tunneled servers can register themselves.
The file contains a top-level key groups, under which each tunnel group is uniquely named.
groups:
"group-name":
hosts:
- "some.host.address.dev" # Host for routing inbound HTTP requests to tunnel group
authentication:
basic:
username: "user"
password: "pass"
Each group body contains import details for configuring the tunnel groups.
hosts
This is an array of strings which is used in routing HTTP requests to the tunnel group when one of the hostnames matches.
authentication
This identifies how to authenticate new tunnels attempting to register with the group.
Multiple authentication strategies can be enabled at once.
The following types are supported:
basic
supports username and password authentication (default scheme Basic
)
bearer
supports static token based matching (default scheme Bearer
)
external
supports offloading authentication and authorization to an external service (default scheme Bearer
)
[!Note]
If enabling both bearer
and external
you will need to override one of their schemes to distinguish them.
Example configuration with multiple authentication strategies
The following contains all three strategies (basic, bearer and external) enabled at once with different schemes:
groups:
"group-name":
hosts:
- "some.host.address.dev" # Host for routing inbound HTTP requests to tunnel group
authentication:
basic:
username: "user"
password: "pass"
bearer:
token: "some-token"
external:
scheme: "JWT"
endpoint: "http://some-external-endpoint/auth/ext"
If no strategies are supplied then authentication is disabled (strongly discouraged).