Clash Rule-Based Proxy and Tunnel in Go

Clash is a rule-based network proxy and tunneling tool written in Go. It routes network traffic through different proxy servers according to configurable rules, allowing users to control how applications and destinations connect to the internet. Its support for multiple proxy protocols, DNS handling, and automated proxy selection makes it useful for network configuration and privacy-focused routing.

Clash uses YAML configuration files to define proxy nodes, routing policies, DNS behavior, and local listening ports. Network administrators and security enthusiasts can use it to build flexible proxy setups without hardcoding every routing decision into an application.

Key Features of Clash

• Local proxy servers: Provides HTTP, HTTPS, and SOCKS-compatible proxy access, with optional authentication for supported configurations.
• Multiple outbound protocols: Supports protocols such as Shadowsocks, VMess, Trojan, Snell, SOCKS5, and HTTP, depending on the core version.
• Rule-based routing: Routes traffic using domain names, GeoIP information, IP address ranges, and supported process-matching rules.
• DNS integration: Supports fake-IP DNS and upstream DNS over HTTPS (DoH) or DNS over TLS (DoT) in compatible versions. These options can help manage DNS resolution and reduce exposure to certain DNS pollution attacks.
• Proxy groups: Supports strategies such as automatic fallback, latency-based selection, and load balancing.
• Remote providers: Loads proxy node lists from remote sources rather than requiring every node to be entered manually.
• Transparent proxying: Supports traffic redirection on compatible Linux and macOS systems, including Netfilter-based configurations.
• REST API: Offers an HTTP controller for supported runtime management and configuration operations.

Some advanced capabilities, including TUN mode, scripting, and rule providers, depend on the particular Clash core or premium implementation. Check the relevant documentation before planning a deployment.

Installing Clash on Linux

You can download a compatible prebuilt binary from the Clash releases page or install the Go package if your environment supports the repository and version you intend to use. The original project documentation specifies Go 1.17 or later for its installation instructions.

Install Clash using Go with the following command:

go install github.com/Dreamacro/clash@latest

Go places the compiled executable in the Go binary directory, commonly $GOPATH/bin or $HOME/go/bin. Make sure that directory is included in your PATH before checking the installation.

clash -v

Review the Clash source repository and its release information to confirm compatibility. Original project availability and support can vary, so check the status of the specific core before using it in production.

Understanding Clash YAML Configuration

Clash uses YAML, a human-readable format for defining its network behavior. The configuration determines which local ports accept connections, how traffic is routed, and which rules are evaluated.

The following example illustrates basic listener settings and a simple routing policy. It is a configuration fragment, not a complete proxy setup with remote nodes.

port: 7890
socks-port: 7891
allow-lan: false
mode: rule
log-level: info

rules:
  - DOMAIN-SUFFIX,example.com,DIRECT
  - MATCH,DIRECT

The port setting defines the local HTTP proxy port, while socks-port specifies the SOCKS listener. Setting allow-lan to false keeps LAN access disabled through this option. In rule mode, Clash evaluates routing rules in order, so more specific rules should appear before broad fallback rules.

The example sends matching traffic directly rather than through a remote proxy. To route traffic through a proxy node, define the appropriate entry under proxies, create a compatible proxy-groups entry, and reference that group in the relevant rules. Consult the Clash documentation for the configuration syntax supported by your version.

DNS Settings and Network Security

The optional DNS section lets users configure upstream resolvers, fake-IP behavior, and domain-specific name resolution. DoH and DoT encrypt DNS queries between the client and a compatible resolver, although they do not automatically protect all network traffic or guarantee anonymity.

Clash can also expose a REST API for management tools. Keep its controller bound to 127.0.0.1 unless remote access is specifically required. If remote access is necessary, configure a strong API secret and restrict access through appropriate network controls. Avoid exposing proxy listeners or management interfaces publicly without authentication and access restrictions.

For additional Linux network administration guidance, see our UFW firewall configuration guide. Combining careful firewall rules with a correctly configured proxy helps limit unintended network exposure.