Chapter 8 Network Address Translation (NAT)

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.

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.

 

 

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 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

 

 

 

193

P-2812HNU-51c User’s Guide