Block all network access in a bubblewrap sandbox with --unshare-net
domain: github.com/containers/bubblewrap · 6 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Add --unshare-net to place the process in a new network namespace, or use --unshare-all which already includes it.
To keep host networking while isolating other namespaces, explicitly add --share-net after --unshare-all (the official demo uses --unshare-all --share-net).
To actually block networking, simply omit --share-net — the demo's own comment: 'remove --share-net to disable networking'.
Drop DNS binds like --ro-bind /etc/resolv.conf /etc/resolv.conf if no network use is intended.
Verify isolation empirically: attempt a TCP connect inside the sandbox and confirm it fails.
Requirements: Unprivileged user namespaces; creating a network namespace via --unshare-net needs no extra privilege.
--unshare-all includes network unsharing — copying the demo verbatim keeps networking ON because it pairs it with --share-net; omitting --share-net silently kills networking.
Flag position matters (sequential option processing): where --share-net appears relative to --unshare-all/--unshare-net changes the result.
The man page only documents that a new network namespace is created; don't assume more granular reachability guarantees (e.g. loopback details) from these docs.
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