Omron CS1W-ETN21 operation manual Mail via the intranet, even if it as a private address

Private and Global Addresses		Section 5-3
	3.	Sending Mail
		• The PLC can send the Ethernet Unit's IP address to the SMTP server by
		mail via the intranet, even if it as a private address.
		• The TCP port number (default: 25) to be used for SMTP cannot be used if
		prohibited by a firewall in the communications path. Also, with some com-
		munications companies, there may be restrictions, based on mail security
		considerations, on using POP before SMTP.
	4.	Receiving Mail
		• The PLC can receive the Ethernet Unit's IP address from the POP3
		server by mail via the intranet, even if it as a private address.
		• The TCP port number (default: 110) to be used for POP3 cannot be used
		if prohibited by a firewall in the communications path.
	5.	Automatic Clock Adjustment
		• The PLC can acquire clock data through the Ethernet Unit's IP address
		from the SNTP server via the intranet, even if it is a private address.
		• The TCP port number (default: 123) to be used for SNTP cannot be used
		if prohibited by a firewall in the communications path.
	6.	Host Name Designation
		• The PLC can acquire the server IP address for the Ethernet Unit's IP
		address from the DNS server via the intranet, even if Ethernet Unit's IP
		address is a private address.
		• The UDP/TCP port number (default: 53) to be used for DNS cannot be
		used if prohibited by a firewall in the communications path.
Note	Network Security and Firewalls
	Setting a global IP address for an Ethernet Unit involves network security con-
	siderations. It is recommended that the user contract with a communications
	company for a dedicated line, rather than using a general line such as a blue
	band. Also, be sure to consult with a network specialist and consider security

measures such as a firewall.

Once a firewall has been set up by a communications company, on the other hand, there may be some applications that cannot be used. Be sure to check first with the communications company.

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