How is firewall-based Antivirus different from client-side AV like Defender or McAfee?
Firewall AV scans traffic in-flight as it crosses the perimeter; client AV scans files at-rest on disk.
| Aspect | Firewall AV | Client AV |
|---|---|---|
| Where | At the perimeter, on the wire | On the endpoint disk/RAM |
| When | While the file is being downloaded | After download, on access, on schedule |
| What it sees | Decrypted traffic (needs SSL Forward Proxy for HTTPS) | Local files, processes, memory |
| Catches | Drive-by downloads, known signatures in transit | Anything that landed on disk, including offline-introduced files (USB) |
Why both? Defense in depth. FW AV stops obvious known threats before they hit the endpoint, reducing endpoint workload. Client AV catches what FW missed (encrypted traffic without decryption, USB sticks, lateral movement).
EICAR test file: EICAR (European Institute for Computer Antivirus Research) defined a harmless standardized string that AV products are coded to flag as if it were a virus. Used to verify AV is working without handling real malware. A typical test downloads it from secure.eicar.org/eicar.com over HTTPS to check the firewall's antivirus profile.
Go deeper:
EICAR test file (Wikipedia) — the exact 68-byte standardized string and why every AV is required to flag it but nothing else.