Dy Na Mic Dns; Packet Filter Firewall - elmeg T444 User Manual

In tro duc ti on
own que ries. The proxy then ta kes the re spon se from the ex ter nal net work and for wards it to the LAN client that pla -
ced the ori gi nal que ry. In ad di ti on, the re sult from the que ry is sto red for a de fi ned time (con fi gu ra ble) to ans wer any
sub se quent que ries of the same type.

Dy na mic DNS

Using Dy na mic DNS you can also of fer your own In ter net ser vi ces (e.g. WEB, FTP or e-mail ser vers). Usu al ly you
must have a fi xed line or a set IP ad dress for this so that you can al ways be rea ched at the same URL (For ex am ple:
www.bin tec-el meg.com).
You are as sig ned a new IP ad dress by the ISP each time you dial in to the In ter net ho we ver. Using Dy na mic DNS you
can link this au to ma tic (dy na mic) IP ad dress with a set name. The rou ter will then in form your Dy na mic DNS ser vi ce
pro vi der (e.g. www.dyndns.org) au to ma ti cal ly of the new IP ad dress. In ter net en qui ries for your Web ser vi ces are
then au to ma ti cal ly for war ded to your dy na mic IP ad dress via your ser vi ce pro vi der.
Using Dynamic DNS
·
Con fi gu re an In ter net ad dress (URL) at a Dy na mic DNS ser vi ce pro vi der. For ex am ple, at
"www.dyndns.org" con fi gu re the ad dress "www.my-ho me pa ge.dyndns.org".
·
Con fi gu re the LAN client of the net work in which you wish to of fer your Web ser vi ces with a set IP ad dress.
For ex am ple, let's say we want to con fi gu re a Web ser ver with the IP ad dress 192.168.1.200.
·
Ac ti va te the Dy na mic DNS functi on in the rou ter and en ter the In ter net ad dress (URL) for your Dy na mic
DNS pro vi der (in the ex am ple here www.dyndns.org).
Add the ne ces sa ry fil ters in the fi re wall to al low the PC with the Web ser vi ces to be rea ched from an ex ter nal
lo ca ti on.
- Con fi gu re port map ping for Port 80 (HTTP pro to col) to IP ad dress 192.168.1.200.
- Con fi gu re the fil ters that per mit in co ming and outgoing WAN connections at Port 80.
·
The rou ter will au to ma ti cal ly in form your Dy na mic DNS pro vi der of your cur rent dy na mic IP ad dress each
time a con nec ti on is set up with the In ter net. The in for ma ti on about the IP ad dress is trans fer red af ter set -
ting up a new In ter net con nec ti on, as well as du ring an ongoing Internet connection.
·
A PC in the In ter net en ters the ad dress (URL) "www.my-ho me pa ge.dyndns.org". In this way it rea ches
your Dy na mic DNS ser vi ce pro vi der. Your ser vi ce pro vi der re rou tes the con nec ti on to your cur rent
dynamic IP address.
·
Any in co ming con nec ti on is hand led in ac cor dan ce with the con fi gu red fil ters. In the ex am ple gi ven here
the in co ming WAN con nec ti on at port 80 is for war ded to the LAN client with the IP ad dress 192.168.1.200.
The avai la ble In ter net si tes of your Web ser ver are dis play ed on the external PC.
NAT
NAT (Net work Adress Trans la ti on) pro tects the con nec ted LAN-clients against at tacks from the In ter net. Here, the
in ter nal IP ad dres ses are not pas sed on to the In ter net. The rou ter car ries out the trans fer to the In ter net and dis tri bu -
tes the in co ming data pa ckets in the in ter nal sys tem. This only re qui res one ex ter nal IP ad dress. The in ter nal IP ad -
dres ses are pro tec ted from at tacks from out si de. The in ter nal IP ad dres ses can not be tar ge ted by ha ckers, as the se IP
ad dres ses are non-ac ces si ble.

Packet Filter Firewall

The in te gra ted fil ter fi re wall pa cket also pro vi des you with en han ced se cu ri ty against at tacks from the In ter net. A fi -
re wall acts as a lo gi cal wall for data pa ckets bet ween the In ter net and the LAN which has »ho les« for cer tain pa ckets
(fi re wall ru les, also known as fil ters), al lo wing the se pa ckets to pass through the wall. The fil ters are des cri bed by ru -
les who se con fi gu ra ti on re qui res ex pert knowled ge about the TCP/IP pro to col fa mi ly. The fi re wall of your PABX sys -
tem can be ea si ly con fi gu red using a Fil ter Wi zard in which you need to in di ca te (in plain text) whet her you wish to
al low de fi ned ap pli ca tions ac cess to the In ter net.
6
Rou ter functions