Show HN: Fence – Sandbox CLI commands with network/filesystem restrictions

Summary

Fence wraps commands in a sandbox that blocks network access by default and restricts filesystem operations based on configurable rules. It's most useful for running semi-trusted code (package installs, build scripts, CI jobs, unfamiliar repos) with controlled side effects, and it can also complement AI coding agents as defense-in-depth. You can also think of Fence as a permission manager for your CLI agents. # Block all network access (default) fence curl https://example.com # → 403 Forbidden # Allow specific domains fence -t code npm install # → uses 'code' template with npm/pypi/etc allowed # Block dangerous commands fence -c " rm -rf / " # → blocked by command deny rules Install curl -fsSL https://raw.githubusercontent.com/Use-Tusk/fence/main/install.sh | sh Other installation methods Go install: go install github.com/Use-Tusk/fence/cmd/fence@latest Build from source: git clone https://github.com/Use-Tusk/fence cd fence go build -o fence ./cmd/fence Additional requirements for Linux: bubblewrap (for sandboxing) (for sandboxing) socat (for network bridging) (for network bridging) bpftrace (optional, for filesystem violation visibility when monitoring with -m ) Usage Basic # Run command with all network blocked (no domains allowed by default) fence curl https://example.com # Run with shell expansion fence -c " echo hello && ls " # Enable debug logging fence -d curl https://example.com # Use a template fence -t code -- claude # Runs Claude Code using `code` template config # Monitor mode (shows violations) fence -m npm install # Show all commands and options fence --help Configuration Fence reads from ~/.fence.json by default: { "extends" : " code " , "network" : { "allowedDomains" : [ " private.company.com " ] }, "filesystem" : { "allowWrite" : [ " . " ] }, "command" : { "deny" : [ " git push " , " npm publish " ] } } Use fence --settings ./custom.json to specify a different config. Import from Claude Code fence import --claude -o ~ /.fence.json Features Network i...