Source note · SIP ALG problems on firewalls and routers
The Cisco IOS XE SIP ALG reads the Via, Contact and Record-Route headers to create firewall pinholes and NAT translation doors.
Checked 2026-09-25
- Vendor
- Cisco
- Product
- Cisco IOS XE NAT
- Subsystem
- NAT ALG
- Deployment
- on-premises
- Region
- not restricted
- Release range
- IOS XE 3S guide
- Checked
- 2026-09-25
Sources
- IP Addressing: NAT Configuration Guide, Cisco IOS XE Release 3S - SIP ALG Hardening for NAT and Firewall — Cisco Systems · tier 2 current vendor documentation · Information About SIP ALG Hardening > Via header and Record-Route handling
Cite this note
APA
WarmTransfer. (2026, September 25). SIP ALG problems on firewalls and routers: source note sip-alg-problems-iosxe-alg-headers. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-alg-problems-iosxe-alg-headers
BibTeX
@misc{warmtransfer-claim-sip-alg-problems-iosxe-alg-headers,
title = {SIP ALG problems on firewalls and routers: source note sip-alg-problems-iosxe-alg-headers},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-alg-problems-iosxe-alg-headers},
note = {Source note sip-alg-problems-iosxe-alg-headers, checked 2026-09-25}
}