Sample
express 4.19.1: Show how `trust proxy` controls whether Express reads `X-Forwarded-For` for `req.ip` and `req.ips`.
Verified sample for npm express 4.19.1: Show how `trust proxy` controls whether Express reads `X-Forwarded-For` for `req.ip` and `req.ips`. The contract ran…
sha256:3a4cd850e24a4583db4efbe2c07c6463fb853a6a7bb75a6d1f365a1b70a6bb0c
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
node linux x64 node node npm
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| node 22 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1 |
2026-08-17 |
| node 22 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1 |
2026-08-18 |
Case
HOW- Goal
- Show how `trust proxy` controls whether Express reads `X-Forwarded-For` for `req.ip` and `req.ips`.
- Packages
- Symbols
-
- request.ip
- request.ips
- application.set
- Environment
- node
- Created
- 2026-08-17T03:16:22Z
Contract
- A request to `/ip` without `trust proxy` ignores `X-Forwarded-For` and `req.ip` is not the forwarded client value.
- After enabling `trust proxy`, the same route returns the first `X-Forwarded-For` hop as `req.ip`.
- In the same two cases, `req.ips` is an empty list without trust and a populated list with trust.
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs