Chapter 8 Network Address Translation (NAT)
P-2812HNU-51c User’s Guide
193
Use this screen to enable or disable the SIP (VoIP) ALG in the P-2812HNU-51c. To
access this screen, click NAT > ALG.
Figure 87 NAT > ALG
Each field is described in the following table.
8.7 Technical Reference
The following section contains additional technical information about the P-
2812HNU-51c features described in this chapter.
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 55 NAT > ALG
LABEL DESCRIPTION
Active SIP ALG Select this check box to allow SIP sessions to pass through the P-
2812HNU-51c. SIP is a signaling protocol used in VoIP (Voice over IP),
the sending of voice signals over Internet Protocol.
Apply Click Apply to save your customized settings.
Table 56 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
