Siemens SIMATIC NET S7-300 - Page 144

5 Configuring Communication Connections
A-144
S7-CPs for Industrial Ethernet Configuring and Commissioning
Release 01/2007
C79000-G8976-C182-07
The following port numbers are reserved; you should not use these for other
purposes in the connection project engineering.
Table 5-7 Reserved Port Numbers
Protocol
Port Number Service
TCP 20, 21 FTP
TCP 25 SMTP
TCP 80 HTTP
TCP 102 RFC1006
TCP 135 RPC -DCOM
UDP 161 SNMP_REQUEST
UDP 34964 PN IO
UDP 65532 NTP
UDP 65533 NTP
UDP 65534 NTP
UDP 65535 NTP