brave / sniproxy

TLS proxy routing TCP connections to backends based on the TLS SNI in the TLS handshake

SNIProxy

SNIProxy is a TLS proxy which, based on the TLS SNI contained in TLS handshakes, routes TCP connections to backends. The proxy does not need the TLS encryption keys and can not decrypt the TLS traffic.

SNIProxy is meant to be simple to use and configure, with sane defaults and few parameters.

Docker image

$ docker run --name sniproxy -p 443:443/tcp \
	-v $(pwd)/sniproxy.conf:/sniproxy.conf \
	atenart/sniproxy:latest -conf sniproxy.conf

SNIProxy can be bound to a custom address or port using the -bind command line option.

$ docker run --name sniproxy -p 443:443/tcp \
	-v $(pwd)/sniproxy.conf:/sniproxy.conf \
	atenart/sniproxy:latest -bind 192.168.0.1:8080 -conf sniproxy.conf

Configuration file

The configuration is made of a list of blocks. Each block represents a route. A route is defined by a list of hostnames, a backend to route the connection to and optional parameters. Empty blocks ({}) can be omitted.

hostname0, hostname1, … {
	backend <IP/hostname>:port {
		optional-parameter
	}
	parameter0
	parameter1 arg0, arg1, …
	…
}

A route can be as simple as:

example.net {
	backend 1.2.3.4:8080
}

Hostnames can contain regexp:

# Matches example.net and all its subdomains.
example.net, *.example.net {
	backend localhost:1234
}

By leaving hostname blank, passthrough mode is enabled:

# Uses example.com:443 as the backend
example.com {
	backend :443
}

Optional parameters

HAProxy's PROXY protocol v1 and v2 are supported.

example.net {
	backend 1.2.3.4:443 {
		# Send a PROXY header using the PROXY protocol v1.
		send-proxy
	}
}

blog.example.net {
	backend 1.2.3.5:443 {
		# Send a PROXY header using the PROXY protocol v2.
		send-proxy-v2
	}
}

SNIProxy also has the ability to block or allow connections based on the client IP address. Single IPs or subnets (using a CIDR range) are supported.

# Deny a single client. All other connections will be routed to the backend.
example.net {
	backend 1.2.3.4:443
	deny 10.0.0.42
}

# Lists can be used as well, either using commas (,) or using multiple
# statements.
example.net {
	backend 1.2.3.4:443
	deny 10.0.0.42, 10.0.0.43, 10.0.0.44
	deny 10.0.0.45
}

# When at least one IP is allowed, all IPs are denied automatically (0.0.0.0/0
# and ::/0).
example.net {
	backend 1.2.3.4:443
	# 192.168.0.42 is allowed, all other IPs are denied.
	allow 192.168.0.42
}

# Example with ranges.
example.net {
	backend 1.2.3.4:443
	deny 192.168.0.0/24
}

# The most specific range wins (if the range is the same, deny wins).
example.net {
	backend 1.2.3.4:443
	# Deny 192.168.0.0/22 except for 192.168.0.2 and 192.168.1.8/29.
	deny 192.168.0.0/22
	allow 192.168.1.8/29, 192.168.0.2
}

SNIProxy can use a different dedicated backend for ACME TLS.

example.net {
	backend 1.2.3.4:443
	acme 1.2.3.5:443
}

ACLs can be bypassed for ACME:

# All IPs are denied except for 192.168.0.0/24 and ACME TLS.
example.net {
	backend 1.2.3.4:443
	acme 1.2.3.5:443
	allow 192.168.0.0/24, acme
}