fix(security): harden sandbox SSH with mandatory HMAC secret, NetworkPolicy, and nonce replay detection#127
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johntmyers merged 2 commits intomainfrom Mar 5, 2026
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…Policy, and nonce replay detection Closes #25 - Make NEMOCLAW_SSH_HANDSHAKE_SECRET mandatory: server and sandbox both refuse to start if the secret is empty/unset. Cluster deployments auto-generate it via openssl rand in the entrypoint script. - Add Kubernetes NetworkPolicy restricting sandbox port 2222 ingress to the gateway pod only, preventing lateral movement from other cluster workloads. - Add NSSH1 nonce replay detection with a TTL-bounded cache, rejecting replayed handshakes within the timestamp validity window. - Add unit tests for verify_preface (valid, replay, expired, bad HMAC, malformed) and env injection.
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…Policy, and nonce replay detection (#127) * fix(security): harden sandbox SSH with mandatory HMAC secret, NetworkPolicy, and nonce replay detection Closes #25 - Make NEMOCLAW_SSH_HANDSHAKE_SECRET mandatory: server and sandbox both refuse to start if the secret is empty/unset. Cluster deployments auto-generate it via openssl rand in the entrypoint script. - Add Kubernetes NetworkPolicy restricting sandbox port 2222 ingress to the gateway pod only, preventing lateral movement from other cluster workloads. - Add NSSH1 nonce replay detection with a TTL-bounded cache, rejecting replayed handshakes within the timestamp validity window. - Add unit tests for verify_preface (valid, replay, expired, bad HMAC, malformed) and env injection. * fix(deploy): pass sshHandshakeSecret in fast deploy helm upgrade --------- Co-authored-by: John Myers <johntmyers@users.noreply.github.com>
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Closes #25
Summary
Hardens the SSH connection path between gateway and sandbox pods with three defense-in-depth improvements: mandatory HMAC handshake secret, Kubernetes NetworkPolicy restricting sandbox SSH ingress to the gateway, and nonce replay detection in the NSSH1 handshake. No UX changes — the secret is auto-generated for cluster deployments.
Changes Made
crates/navigator-sandbox/src/lib.rs: Fail startup ifNEMOCLAW_SSH_HANDSHAKE_SECRETis empty/unset when SSH is enabled (replaces silentunwrap_or_default())crates/navigator-sandbox/src/ssh.rs: AddNonceCachetype (Arc<Mutex<HashMap<String, Instant>>>), background reaper task, nonce replay rejection inverify_preface(), and 6 unit testscrates/navigator-server/src/lib.rs: Add startup validation rejecting emptyssh_handshake_secretcrates/navigator-server/src/sandbox/mod.rs: Always injectNEMOCLAW_SSH_HANDSHAKE_SECRETenv var (remove conditional guard), add env injection testdeploy/helm/navigator/templates/networkpolicy.yaml: New NetworkPolicy restricting sandbox pod port 2222 ingress to gateway pods only (gated bynetworkPolicy.enabled)deploy/helm/navigator/templates/statefulset.yaml: WireNEMOCLAW_SSH_HANDSHAKE_SECRETenv var into gateway poddeploy/helm/navigator/values.yaml: Addserver.sshHandshakeSecret(required) andnetworkPolicy.enabled: truedeploy/kube/manifests/navigator-helmchart.yaml: AddsshHandshakeSecretplaceholderdeploy/docker/cluster-entrypoint.sh: Auto-generate secret viaopenssl rand -hex 32at cluster deploy timearchitecture/sandbox-connect.md: Document mandatory secret, nonce replay detection, and NetworkPolicyDeviations from Plan
None — implemented as planned.
Tests Added
verify_prefacetests incrates/navigator-sandbox/src/ssh.rs(valid preface, replay rejection, expired timestamp, invalid HMAC, malformed input, distinct nonces); 1 env injection test incrates/navigator-server/src/sandbox/mod.rse2e/Documentation Updated
architecture/sandbox-connect.md: Added nonce replay detection section, mandatory handshake secret section, NetworkPolicy in security model, updated config referenceVerification