Source note · SIP ALG problems on firewalls and routers
If a capture on the public side of a PAT device shows a private address still present in a SIP header or in the SDP o= field while other fields were translated, that pattern matches documented partial-translation limits of SIP inspection. It is not proof that no ALG is present.
inferred · Checked 2026-09-25
- Vendor
- Cisco
- Product
- Cisco Secure Firewall ASA
- Subsystem
- troubleshooting
- Deployment
- on-premises
- Region
- not restricted
- Release range
- ASA 9.23
- Status
- inferred
- Checked
- 2026-09-25
Sources
- CLI Book 2: Cisco Secure Firewall ASA Firewall CLI Configuration Guide 9.23 - Inspection for Voice and Video Protocols — Cisco Systems · tier 2 current vendor documentation · PAT Limitations for SIP Inspection
Cite this note
APA
WarmTransfer. (2026, September 25). SIP ALG problems on firewalls and routers: source note sip-alg-problems-capture-private-ip-leak-signal. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-alg-problems-capture-private-ip-leak-signal
BibTeX
@misc{warmtransfer-claim-sip-alg-problems-capture-private-ip-leak-signal,
title = {SIP ALG problems on firewalls and routers: source note sip-alg-problems-capture-private-ip-leak-signal},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-alg-problems-capture-private-ip-leak-signal},
note = {Source note sip-alg-problems-capture-private-ip-leak-signal, checked 2026-09-25}
}