Configure the sandboxed Bash tool changedsandboxing
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474474Network access is controlled through a proxy server running outside the sandbox:
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476* **Domain restrictions**: no domains are pre-allowed by default. The first time a command needs a new domain, Claude Code prompts for approval, or in [auto mode](/docs/en/permission-modes#eliminate-prompts-with-auto-mode) sends the request to the classifier. When you're prompted, choosing Yes allows the host for the rest of the current session, so later connections to the same host do not prompt again. Pre-allow domains with [`allowedDomains`](/docs/en/settings#sandbox-settings) to avoid the prompt entirely. `WebFetch` allow rules also pre-allow domains, as described in [Permission rules](#permission-rules).
476* **Domain restrictions**: Claude Code pre-allows no domains by default. The first time a command needs a new domain, Claude Code prompts for approval, or in [auto mode](/docs/en/permission-modes#eliminate-prompts-with-auto-mode) sends the request to the classifier. If you choose Yes when prompted, Claude Code allows the host for the rest of the current session and doesn't prompt again for later connections to the same host. If you choose "Yes, and don't ask again", Claude Code saves a `WebFetch(domain:...)` allow rule to your [local settings](/docs/en/permissions#permission-system), so the host stays allowed in future sessions. Pre-allow domains with [`allowedDomains`](/docs/en/settings#sandbox-settings) to avoid the prompt entirely. Claude Code also pre-allows domains from `WebFetch` allow rules, as described in [Permission rules](#permission-rules).
477477* **Strict allowlist**: if you set [`strictAllowlist`](/docs/en/settings#sandbox-settings) to `true` in user, managed, or CLI `--settings` settings, Claude Code denies sandboxed commands access to any host outside the allowlist instead of prompting. The allowlist is the same one the sandbox otherwise prompts against: `allowedDomains` plus domains from `WebFetch(domain:...)` allow rules, or only the managed settings entries when `allowManagedDomainsOnly` is set. Claude Code enforces this for sandboxed commands only; in-process tools such as `WebFetch` still follow their [permission rules](#permission-rules). Setting it in a repository's `.claude/settings.json` or `.claude/settings.local.json` has no effect. Requires Claude Code v2.1.219 or later.
478478* **Managed lockdown**: if [`allowManagedDomainsOnly`](/docs/en/settings#sandbox-settings) is set in managed settings, non-allowed domains are blocked automatically instead of prompting, and only `allowedDomains` and `WebFetch(domain:...)` allow rules from managed settings are honored.
479479* **Corporate proxy**: when your network requires outbound traffic to go through a corporate proxy, set `HTTPS_PROXY`, `HTTP_PROXY`, and `NO_PROXY` as [proxy configuration](/docs/en/network-config#proxy-configuration) describes, in the `env` block of your settings so that [background agents](/docs/en/network-config#set-network-variables-in-settings-not-the-shell) get them too, or in the environment you launch Claude Code from. Claude Code enforces the domain allowlist and then tunnels allowed connections through that upstream proxy.
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487487#### IPv6 addresses in domain lists
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489489The sandbox's domain lists are `allowedDomains`, `deniedDomains`, and the `WebFetch(domain:...)` rules that feed them. To match an IPv6 address in any of them, write the literal in brackets: `"[::1]"` matches that address on every port, and `"[::1]:443"` matches it on port 443 only. Write the port as a number from 1 to 65535 with no leading zeros. The bracketed form requires Claude Code v2.1.229 or later. Before v2.1.229, when the text after an unbracketed entry's last colon was a port number, Claude Code read it as one, so `::1:443` named the address `::1` on port 443.
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491When you choose "Yes, and don't ask again" at the network approval prompt for an IPv6 address, Claude Code saves the `WebFetch(domain:...)` rule with the address bracketed, so the rule keeps matching the address in future sessions.
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491493An unbracketed entry with two or more colons is ambiguous: `::1:443` is both a complete IPv6 address and an address followed by a port. Claude Code enforces ambiguous spellings conservatively instead of guessing which reading you meant:
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