dumbproxy

README

dumbproxy

Dumbest HTTP proxy ever.

Features

• Cross-platform (Windows/Mac OS/Linux/Android (via shell)/*BSD)
• Deployment with a single self-contained binary
• Zero-configuration
• Supports CONNECT method and forwarding of HTTPS connections
• Supports Basic proxy authentication
  • Via auto-reloaded NCSA httpd-style passwords file
  • Via static login and password
  • Via HMAC signatures provisioned by central authority (e.g. some webservice)
• Supports TLS operation mode (HTTP(S) proxy over TLS)
  • Supports client authentication with client TLS certificates
  • Native ACME support (can issue TLS certificates automatically using Let's Encrypt or BuyPass)
• Per-user bandwidth limits
• HTTP/2 support
• Optional DNS cache
• Resilient to DPI (including active probing, see hidden_domain option for authentication providers)
• Connecting via upstream HTTP(S)/SOCKS5 proxies (proxy chaining)
• systemd socket activation
• Scripting with JavaScript:
  • Access filter by JS function
  • Upstream proxy selection by JS function

Installation

Binary download

Pre-built binaries available on releases page.

From source

Alternatively, you may install dumbproxy from source. Run within source directory

go install

Docker

Docker image is available as well. Here is an example for running proxy as a background service:

docker run -d \
    --security-opt no-new-privileges \
    -p 8080:8080 \
    --restart unless-stopped \
    --name dumbproxy \
    ghcr.io/senseunit/dumbproxy -auth 'static://?username=admin&password=123456'

Snap Store

sudo snap install dumbproxy

Usage

Just run program and it'll start accepting connections on port 8080 (default).

Example: plain proxy

Run proxy on port 1234 with Basic authentication with username admin and password 123456:

dumbproxy -bind-address :1234 -auth 'static://?username=admin&password=123456'

Example: HTTP proxy over TLS (LetsEncrypt automatic certs)

Run HTTPS proxy (HTTP proxy over TLS) with automatic certs from LetsEncrypt on port 443 with Basic authentication with username admin and password 123456:

dumbproxy -bind-address :443 -auth 'static://?username=admin&password=123456' -autocert

Example: HTTP proxy over TLS (BuyPass automatic certs)

Run HTTPS proxy (HTTP proxy over TLS) with automatic certs from BuyPass on port 443 with Basic authentication with username admin and password 123456:

dumbproxy \
	-bind-address :443 \
	-auth 'static://?username=admin&password=123456' \
	-autocert \
	-autocert-acme 'https://api.buypass.com/acme/directory' \
	-autocert-email YOUR-EMAIL@EXAMPLE.ORG \
	-autocert-http :80

Using HTTP-over-TLS proxy

It's quite trivial to set up program which supports proxies to use dumbproxy in plain HTTP mode. However, using HTTP proxy over TLS connection with browsers is little bit tricky. Note that TLS must be enabled (-cert and -key options or -autocert option) for this to work.

Routing all browsers on Windows via HTTPS proxy

Open proxy settings in system's network settings:

Turn on setup script option and set script address:

data:,function FindProxyForURL(u, h){return "HTTPS example.com:8080";}

where instead of example.com:8080 you should use actual address of your HTTPS proxy.

Note: this method will not work with MS Edge Legacy.

Using with Firefox

Option 1. Inline PAC file in settings.

Open Firefox proxy settings, switch proxy mode to "Automatic proxy configuration URL". Specify URL:

data:,function FindProxyForURL(u, h){return "HTTPS example.com:8080";}

Option 2. Browser extension.

Use any proxy switching browser extension which supports HTTPS proxies like this one.

Using with Chrome

Option 1. CLI option.

Specify proxy via command line:

chromium-browser --proxy-server='https://example.com:8080'

Option 2. Browser extension.

Use any proxy switching browser extension which supports HTTPS proxies like this one.

Using with other applications

It is possible to expose remote HTTPS proxy as a local plaintext HTTP proxy with help of external application which performs remote communication via TLS and exposes local plaintext socket. steady-tun appears to be most suitable for this because it supports connection pooling to hide connection delay.

Using with Android

1. Run proxy as in examples above.
2. Install Adguard on your Android: Guide.
3. Follow this guide, skipping server configuration. Use proxy type HTTPS if you set up TLS-enabled server or else use HTTP type.
4. Enjoy!

Authentication

Authentication parameters are passed as URI via -auth parameter. Scheme of URI defines authentication metnod and query parameters define parameter values for authentication provider.

• none - no authentication. Example: none://. This is default.
• static - basic authentication for single login and password pair. Example: static://?username=admin&password=123456. Parameters:
  • username - login.
  • password - password.
  • hidden_domain - if specified and is not an empty string, proxy will respond with "407 Proxy Authentication Required" only on specified domain. All unauthenticated clients will receive "400 Bad Request" status. This option is useful to prevent DPI active probing from discovering that service is a proxy, hiding proxy authentication prompt when no valid auth header was provided. Hidden domain is used for generating 407 response code to trigger browser authorization request in cases when browser has no prior knowledge proxy authentication is required. In such cases user has to navigate to any hidden domain page via plaintext HTTP, authenticate themselves and then browser will remember authentication.
• basicfile - use htpasswd-like file with login and password pairs for authentication. Such file can be created/updated with command like this: dumbproxy -passwd /etc/dumbproxy.htpasswd username password or with htpasswd utility from Apache HTTPD utils. path parameter in URL for this provider must point to a local file with login and bcrypt-hashed password lines. Example: basicfile://?path=/etc/dumbproxy.htpasswd. Parameters:
  • path - location of file with login and password pairs. File format is similar to htpasswd files. Each line must be in form <username>:<bcrypt hash of password>. Empty lines and lines starting with # are ignored.
  • hidden_domain - same as in static provider
  • reload - interval for conditional password file reload, if it was modified since last load. Use negative duration to disable autoreload. Default: 15s.
• hmac - authentication with HMAC-signatures passed as username and password via basic authentication scheme. In that scheme username represents user login as usual and password should be constructed as follows: password := urlsafe_base64_without_padding(expire_timestamp || hmac_sha256(secret, "dumbproxy grant token v1" || username || expire_timestamp)), where expire_timestamp is 64-bit big-endian UNIX timestamp and || is a concatenation operator. This Python script can be used as a reference implementation of signing. Dumbproxy itself also provides built-in signer: dumbproxy -hmac-sign <HMAC key> <username> <validity duration>. Parameters of this auth scheme are:
  • secret - hex-encoded HMAC secret key. Alternatively it can be specified by DUMBPROXY_HMAC_SECRET environment variable. Secret key can be generated with command like this: openssl rand -hex 32 or dumbproxy -hmac-genkey.
  • hidden_domain - same as in static provider
• cert - use mutual TLS authentication with client certificates. In order to use this auth provider server must listen sockert in TLS mode (-cert and -key options) and client CA file must be specified (-cacert). Example: cert://. Parameters of this scheme are:
  • blacklist - location of file with list of serial numbers of blocked certificates, one per each line in form of hex-encoded colon-separated bytes. Example: ab:01:02:03. Empty lines and comments starting with # are ignored.
  • reload - interval for certificate blacklist file reload, if it was modified since last load. Use negative duration to disable autoreload. Default: 15s.

Scripting

With the dumbproxy, it is possible to modify request processing behaviour using simple scripts written in the JavaScript programming language.

Access filter by JS script

It is possible to filter (allow or deny) requests with simple access JS function. Such function can be loaded with the -js-access-filter option. Option value must specify location of script file where access function is defined.

access function is invoked with following parameters:

1. Request (Object). It contains following properties:
   • method (String) - HTTP method used in request (CONNECT, GET, POST, PUT, etc.).
   • url (String) - URL parsed from the URI supplied on the Request-Line.
   • proto (String) - the protocol version for incoming server requests.
   • protoMajor (Number) - numeric major protocol version.
   • protoMinor (Number) - numeric minor protocol version.
   • header (Object) - mapping of String headers (except Host) in canonical form to an Array of their String values.
   • contentLength (Number) - length of request body, if known.
   • transferEncoding (Array) - lists the request's transfer encodings from outermost to innermost.
   • host (String) - specifies the host on which the URL is sought. For HTTP/1 (per RFC 7230, section 5.4), this is either the value of the "Host" header or the host name given in the URL itself. For HTTP/2, it is the value of the ":authority" pseudo-header field.
   • remoteAddr (String) - client's IP:port.
   • requestURI (String) - the unmodified request-target of the Request-Line (RFC 7230, Section 3.1.1) as sent by the client to a server.
2. Destination address (Object). It's an address where actual connection is about to be created. It contains following properties:
   • network (String) - connection type. Should be "tcp" in most cases unless restricted to specific address family ("tcp4" or "tcp6").
   • originalHost (String) - original hostname or IP address parsed from request.
   • resolvedHost (String) - resolved hostname from request or null if resolving was not performed (e.g. if upstream dialer is a proxy).
   • port (Number) - port number.
3. Username (String). Name of the authenticated user or an empty string if there is no authentication.

access function must return boolean value, true allows request and false forbids it. Any exception will be reported to log and the corresponding request will be denied.

Also it is possible to use builtin print function to print arbitrary values into dumbproxy log for debugging purposes.

Example:

// Deny unsafe ports for HTTP and non-SSL ports for HTTPS.

const SSL_ports = [
	443,
]
const Safe_ports = [
	80,                // http
	21,                // ftp
	443,               // https
	70,                // gopher
	210,               // wais
	280,               // http-mgmt
	488,               // gss-http
	591,               // filemaker
	777,               // multiling http
]
const highPortBase = 1025

function access(req, dst, username) {
	if (req.method == "CONNECT") {
		if (SSL_ports.includes(dst.port)) return true
	} else {
		if (dst.port >= highPortBase || Safe_ports.includes(dst.port)) return true
	}
	return false
}

Upstream proxy selection by JS script

dumbproxy can select upstream proxy dynamically invoking getProxy JS function from file specified by -js-proxy-router option.

Note that this option can be repeated multiple times, same as -proxy option for chaining of proxies. These two options can be used together and order of chaining will be as they come in command line. For generalization purposes we can say that -proxy option is equivalent to -js-proxy-router option with script which returns just one static proxy.

getProxy function is invoked with the same parameters as the access function. But unlike access function it is expected to return proxy URL in string format scheme://[user:password@]host:port or empty string "" if no additional upstream proxy needed (i.e. direct connection if there are no other proxy dialers defined in chain).

Supported proxy schemes are:

• http - regular HTTP proxy with the CONNECT method support.
• https - HTTP proxy over TLS connection.
• socks5, socks5h - SOCKS5 proxy with hostname resolving via remote proxy.

Example:

// Redirect .onion hidden domains to Tor SOCKS5 proxy

function getProxy(req, dst, username) {
	if (dst.originalHost.replace(/\.$/, "").toLowerCase().endsWith(".onion")) {
		return "socks5://127.0.0.1:9050"
	}
	return ""
}

[!NOTE]
getProxy can be invoked once or twice per request. If first invocation with null resolved host address returns "direct" mode and no other dialer has suppressed name resolving, name resolution will be performed and getProxy will be invoked once again with resolved address for the final decision.

This shouldn't be much of concern, though, if getProxy function doesn't use dst.resolvedHost and returns consistent values across invocations with the rest of inputs having same values.

Synopsis

$ ~/go/bin/dumbproxy -h
Usage of /home/user/go/bin/dumbproxy:
  -auth string
    	auth parameters (default "none://")
  -autocert
    	issue TLS certificates automatically
  -autocert-acme string
    	custom ACME endpoint (default "https://acme-v02.api.letsencrypt.org/directory")
  -autocert-dir string
    	path to autocert cache (default "/home/user/.dumbproxy/autocert")
  -autocert-email string
    	email used for ACME registration
  -autocert-http string
    	listen address for HTTP-01 challenges handler of ACME
  -autocert-whitelist value
    	restrict autocert domains to this comma-separated list
  -bind-address string
    	HTTP proxy listen address. Set empty value to use systemd socket activation. (default ":8080")
  -bind-reuseport
    	allow multiple server instances on the same port
  -bw-limit uint
    	per-user bandwidth limit in bytes per second
  -bw-limit-buckets uint
    	number of buckets of bandwidth limit (default 1048576)
  -bw-limit-separate
    	separate upload and download bandwidth limits
  -cafile string
    	CA file to authenticate clients with certificates
  -cert string
    	enable TLS and use certificate
  -ciphers string
    	colon-separated list of enabled ciphers
  -deny-dst-addr value
    	comma-separated list of CIDR prefixes of forbidden IP addresses (default 127.0.0.0/8, 0.0.0.0/32, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16, ::1/128, ::/128, fe80::/10)
  -disable-http2
    	disable HTTP2
  -dns-cache-neg-ttl duration
    	TTL for negative responses of DNS cache (default 1s)
  -dns-cache-timeout duration
    	timeout for shared resolves of DNS cache (default 5s)
  -dns-cache-ttl duration
    	enable DNS cache with specified fixed TTL
  -hmac-genkey
    	generate hex-encoded HMAC signing key of optimal length
  -hmac-sign
    	sign username with specified key for given validity period. Positional arguments are: hex-encoded HMAC key, username, validity duration.
  -ip-hints string
    	a comma-separated list of source addresses to use on dial attempts. "$lAddr" gets expanded to local address of connection. Example: "10.0.0.1,fe80::2,$lAddr,0.0.0.0,::"
  -js-access-filter string
    	path to JS script file with the "access" filter function
  -js-access-filter-instances int
    	number of JS VM instances to handle access filter requests (default 4)
  -js-proxy-router value
    	path to JS script file with the "getProxy" function
  -js-proxy-router-instances int
    	number of JS VM instances to handle proxy router requests (default 4)
  -key string
    	key for TLS certificate
  -list-ciphers
    	list ciphersuites
  -max-tls-version value
    	maximum TLS version accepted by server (default TLS13)
  -min-tls-version value
    	minimal TLS version accepted by server (default TLS12)
  -passwd string
    	update given htpasswd file and add/set password for username. Username and password can be passed as positional arguments or requested interactively
  -passwd-cost int
    	bcrypt password cost (for -passwd mode) (default 4)
  -proxy value
    	upstream proxy URL. Can be repeated multiple times to chain proxies. Examples: socks5h://127.0.0.1:9050; https://user:password@example.com:443
  -req-header-timeout duration
    	amount of time allowed to read request headers (default 30s)
  -user-ip-hints
    	allow IP hints to be specified by user in X-Src-IP-Hints header
  -verbosity int
    	logging verbosity (10 - debug, 20 - info, 30 - warning, 40 - error, 50 - critical) (default 20)
  -version
    	show program version and exit

See Also

• Project Wiki
• Community in Telegram