Mut ^{[Multi-usage tunnel]}, a DeepAQ Labs project

WARNING: This project is for research purposes only. We take no responsibility for the use of the project. Usage in the real environment is not recommended. You may view the license part below.

License

Mut is licensed under the AGPLv3 license.

Usage

Usage of mut:
  -in string (multiple values supported)
        inbound config, scheme://[username:password@]host:port[/?option=value...]
  -out string (multiple values supported)
        outbound config, [tag:]scheme://[username:password@]host:port[/?option=value...]
  -rules string
        router rules, rule1:tag1[;rule2:tag2...][;final:tag]
  -dns string
        dns config, protocol://host:port[/path...]
  -debug int
        localhost debug port
  -stdin
        receive other arguments from stdin

Configuration

New URL schemes

Starting from 2021.06 release, inbound and outbound configuration URL schemes will use protocol+transport[+transport...] format.

Starting from 2022.03 release, each outbound can contain a unique tag for routing.

tls transport

Adds TLS 1.2/1.3 support over a TCP connection.

Options:

• cert: (inbound only) path to a base64-encoded certificate file
• key: (inbound only) path to a base64-encoded private key file
• host: (optional, outbound only) overrides the SNI server name. If not specified, the outbound hostname will be used as server name.
• alpn: (optional, outbound only) comma-seperated Application-Layer Protocol Negotiation values.
• public_key: (optional, outbound only) use server certificate public key instead of CA to verify identity

mux transport

Adds connection multiplexing ability over a TCP connection, powered by Yamux.

Options:

• concurrency: (outbound only) the number of concurrent TCP connections to open.

Inbound protocols

forward protocol

Forwards all TCP traffic to the given target destination.

Options:

• target: address of the target destination

http protocol

Receives normal HTTP requests and CONNECT requests. HTTP basic authorization is supported. HTTP/2 is automatically enabled if the underlying transport is tls, and h2 is present in ALPN values sent by client.

https scheme is now an alias of http+tls.

h3 protocol (experimental)

Receives normal and CONNECT requests in HTTP/3 over QUIC.

Options: same as tls inbound transport.

socks protocol

Receives SOCKS5 requests. Username and password authorization is supported. Currently, UDP bind requests are not supported but local UDP relay gateway is supported.

Options:

• udp=1: enables local UDP relay gateway on the same port.

mix protocol

Receives both HTTP/1.1 and SOCKS5 requests. The underlying protocol is automatically determined by the first packet received from client.

Options: same as socks protocol.

tun protocol

Processes TCP/UDP/ICMP connections from a tun device. tun inbound can be initialized using:

• device name: tun://tun<number> (Linux) or tun://utun<number> (macOS)
• file descriptor: tun://?fd=<fd> (Linux/macOS)
• fd received from unix socket: tun://?fdpath=<socket path> (Linux/macOS)

Options:

• mtu (optional): Override the default mtu (1500) of tun device.
• dnsgw (optional): Forward all DNS requests to a specified server.

l2tp protocol

Accepts L2TP (without IPSec) connections on port 1701. Client compatibility is limited to RouterOS and Linux (xl2tpd).

Options:

• dnsgw: Forward all DNS requests to a specified server.

Outbound protocols

direct protocol

Sends all outbound traffic directly.

socks protocol

Sends all outbound traffic to a target that receives SOCKS5 requests. Username and password authorization is supported.

http protocol

Sends all outbound traffic to a target that receives HTTP/1.1 CONNECT requests. HTTP basic authorization is supported.

https scheme is now an alias of http+tls.

h2 protocol

Sends all outbound traffic to a target that receives HTTP/2 CONNECT requests over a TLS 1.2/1.3 connection.

h2 scheme is equivalent to h2+tls.

Options:

• concurrency: (optional, default=8) specifies how many concurrent TCP connections (at least) to open.
• alive: (optional) specifies how long a TCP connection can keep. If not specified, there will be no limit to the TCP keepalive time.

h3 protocol (experimental)

Sends all outbound traffic to a target that receives HTTP/3 CONNECT requests over QUIC.

DNS config

By default, all DNS requests will be handled by OS. If a DNS server is specified, outbound traffic will use the specified server.

Supported DNS server types

• Plain UDP, example: udp://1.1.1.1:53
• DNS over HTTPS (DoH), example: doh://1.1.1.1/dns-query

Local DNS server and Fake IP

You can open a local DNS server by adding local_listen=host:port parameter to the DNS config URL. The local server supports plain UDP protocol.

If fake_ip=1 parameter is specified, the local DNS server will always return fake IPs. The DNS resolve process will be done when the inbound receives a request with a fake IP address. This feature should only be used for integration with other platforms, for example, tun devices.

Routing rules config

Mut includes a rule-based router for handling inbound requests. By default, all connections will be sent through the default outbound.

Rules format

Routing rules are joined by semicolon (;). Each rule is in a format of condition,tag.

Conditions

• domains: condition: matches domain suffixes, following by a file containing domain suffixes, one in a line. Example: domains:1.txt
• cidr: condition: matches IPv4 CIDR address ranges, following by a file containing CIDRs, one in a line. Example: cidr:1.txt

Tags

• An outbound tag name: the connection will be sent through the specified outbound.
• default: the connection will be sent through the default outbound without tag.
• direct: the connection will be sent directly.
• reject: the connection will be rejected.

Local debug config

Specifying -debug <port> argument will open a local HTTP server for debugging.

Debugging endpoints

• /debug/pprof: for Go pprof usage.
• /debug/mut/dns: shows the content of DNS cache and fake IP pool, if corresponding feature is enabled.