User`s guide
Table Of Contents
- VMG8924-B10A and VMG8924- B30A Series
- User’s Guide
- Technical Reference
- Network Map and Status Screens
- Broadband
- Wireless
- Home Networking
- 7.1 Overview
- 7.2 The LAN Setup Screen
- 7.3 The Static DHCP Screen
- 7.4 The UPnP Screen
- 7.5 Installing UPnP in Windows Example
- 7.6 Using UPnP in Windows XP Example
- 7.7 The Additional Subnet Screen
- 7.8 The STB Vendor ID Screen
- 7.9 The 5th Ethernet Port Screen
- 7.10 The LAN VLAN Screen
- 7.11 The Wake on LAN Screen
- 7.12 Technical Reference
- Routing
- Quality of Service (QoS)
- Network Address Translation (NAT)
- Dynamic DNS Setup
- Interface Group
- USB Service
- Power Management
- Firewall
- MAC Filter
- Parental Control
- Scheduler Rule
- Certificates
- VPN
- Voice
- Log
- Traffic Status
- VoIP Status
- ARP Table
- Routing Table
- IGMP/MLD Status
- xDSL Statistics
- 3G Statistics
- User Account
- Remote Management
- TR-069 Client
- TR-064
- SNMP
- Time Settings
- E-mail Notification
- Logs Setting
- Firmware Upgrade
- Configuration
- Diagnostic
- Troubleshooting
- Customer Support
- Setting up Your Computer’s IP Address
- IP Addresses and Subnetting
- Pop-up Windows, JavaScripts and Java Permissions
- Wireless LANs
- IPv6
- Services
- Legal Information
- Index

Chapter 10 Network Address Translation (NAT)
VMG8924-B10A and VMG8924-B30A Series User’s Guide
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10.10.4 NAT Application
The following figure illustrates a possible NAT application, where three inside LANs (logical LANs
using IP alias) behind the Device can communicate with three distinct WAN networks.
Figure 96 NAT Application With IP Alias
Port Forwarding: Services and Port Numbers
The most often used port numbers are shown in the following table. Please refer to RFC 1700 for
further information about port numbers. Please also refer to the Supporting CD for more examples
and details on port forwarding and NAT.
Table 69 Services and Port Numbers
SERVICES PORT NUMBER
ECHO 7
FTP (File Transfer Protocol) 21
SMTP (Simple Mail Transfer Protocol) 25
DNS (Domain Name System) 53
Finger 79
HTTP (Hyper Text Transfer protocol or WWW, Web) 80
POP3 (Post Office Protocol) 110
NNTP (Network News Transport Protocol) 119
SNMP (Simple Network Management Protocol) 161
SNMP trap 162
PPTP (Point-to-Point Tunneling Protocol) 1723