Kerio Tech KERIO WINROUTE FIREWALL 6 User Manual download pdf (Page 358)

Glossary of terms

358

DMZ

DMZ (demilitarized zone) is a reserved network area where services available both from

the Internet and from the LAN are run (e.g. a company’s public web server). DMZ provides

an area, where servers accessible for public are be located separately, so they cannot be

misused for cracking into the LAN.

More information can be found for example at Wikipedia.

DNS

DNS (Domain Name System) A worldwide distributed database of Internet hostnames and

their associated IP address. Computers use Domain Name Servers to resolve host names

to IP addresses. Names are sorted in hierarchized domains.

Firewall

Software or hardware device that protects a computer or computer network against at-

tacks from external sources (typically from the Internet).

In this guide, the word ﬁrewall represents the WinRoute host.

FTP

File Transfer Protocol. The FTP protocol uses two types of TCP connection: control and

data. The control connection is always established by a client. Two FTP modes are distin-

guished according to a method how connection is established:

• active mode — data connection is established from the server to a client (to the

port speciﬁed by the client). This mode is suitable for cases where the ﬁrewall

is at the server’s side, however, it is not supported by some clients (e.g. by web

browsers).

• passive mode — data connection is established also by the client (to the port

required by the server). This mode is suitable for cases where the ﬁrewall is at

the client’s side. It should be supported by any FTP client.

Note: WinRoute includes special support (protocol inspector) for FTP protocol. Therefore,

both FTP modes can be used on LAN hosts.

Gateway

Network device or a computer connecting two diﬀerent subnets. If traﬃc to all the other

(not speciﬁed) networks is routed through a gateway, it is called the default gateway.

See also default gateway.

Greylisting

A method of protection of SMTP servers from spam. If an email message sent by an

unknown sender is delivered to the server, the server rejects it for the ﬁrst time (so called

temporary delivery error). Legitimate senders attempt resend the message after some

time. SMTP server lets the message in and considers the sender as trustworthy since

then, not blocking their messages any longer. Most spam senders try to send as great

volume in as short time as possible and stay anonymous. Therefore, they usually do not

repeat sending the message and focus on another SMTP server.

More information (in English) can be found for example at Wikipedia.

1 2 ... 353 354 355 356 357 358 359 360 361 362 363 ... 367 368

No comments

Kerio Tech KERIO WINROUTE FIREWALL 6 User Manual Page 358