Operating instructions

If the con nec ti on is dis rup ted and an at tempt is to be made la ter to re-estab lish the con nec ti on, this cy cle is res tar ted

be gin ning with the first en try in the list.

Firewall

When you use NAT, the PCs con nec ted to the PABX are well pro tec ted against at tacks from the In ter net. Here, your

PC is not lin ked di rect ly with the In ter net, but con nec ted via the ISDN rou ter in te gra ted into the PABX sys tem. In ter -

nal IP ad dres ses are not pas sed on to the In ter net. The ISDN 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. Your PC is pro tec ted from at tacks from out si de.

If you wish to have ad di tio nal se cu ri ty you can also use the in te gra ted pa cka ge Fil ter Fi re wall. A fi re wall acts as a lo gi -

cal wall for data pa ckets bet ween the In ter net and the ISDN rou ter 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.

In the de fault set ting the fi re wall is ac ti ve only with a mi ni mum of pro tec ti on (Net bi os fil ter). This fil ter pre vents the

for war ding of Net bi os name que ries from Wind ows PCs to the In ter net. As the na mes of the Wind ows PCs are not

known in the In ter net, it is not mea ning ful to estab lish an In ter net con nec ti on for for war ding the name que ry. This

could re sult in con si der able costs, as the se name que ries oc cur fre quent ly, mea ning that the In ter net con nec ti on

would prac ti cal ly ne ver be ter mi na ted.

Note

The de fi ned fil ters of the Fil ter Wi zard have been con fi gu red ba sed on our la test knowled ge. We can, ho we ver, pro -

vi de no gua ran tee for the functi on of the fil ters. Use of a fi re wall should go hand in hand with use of vi rus scan ning

soft wa re on all your PCs! Fi re walls and vi rus scan ners co ver dif fe rent are as of data se cu ri ty and are an ideal com pli -

ment to one anot her, but can not re pla ce one anot her.

Af ter you have con fi gu red the PABX sys tem and are rea dy to send data to the PABX, a mes sa ge will be is su ed no ti fy -

ing you that no ot her fil ter is cur rent ly con fi gu red ex cept for the Net BI OS fil ter. You then have to de ci de whet her you

wish to con fi gu re the full pro tec ti on pro vi ded by the fi re wall (re com men ded), or whet her you wish to send the data

to the PABX sys tem as cur rent ly con fi gu red.

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.

We re com mend con fi gu ring the fi re wall fil ters with the aid of the Fil ter Wi zard to en su re con fi gu ra ti on(s) ap pro -

pria te for and com pa ti ble to the ap pli ca tions being used. The se fil ters pro vi de pro tec ti on against data pa ckets from

the In ter net that may re sult in you being char ged for cer tain con nec tions. The functi on for the “Au to ma tic con nec ti -

on se tup”, for ex am ple, may ot her wi se not al ways be en su red. A port scan from the In ter net (usu al ly the in iti al sta ge

of a hack at tack) may so me ti mes oc cur; the te le pho ne sys tem fi re wall then re plies to this scan with »Re ject pa ckets«.

But this may ne ver the less re sult in data traf fic that pre vents au to ma tic se tup of a con nec ti on.

To start the Fil ter Wi zard in the con fi gu ra ti on item »Net work fil ters« click the but ton »Fil ter Wi zard«. The fol lo wing

mask is then dis play ed af ter a war ning that star ting the Fil ter Wi zard will de le te all fil ters that have been con fi gu red

up to this time:

The Fil ter Wi zard can be res tar ted at any time to

load a mo di fied (edi ted) con fi gu ra ti on into the

PABX sys tem. Click the but ton »Send con fi gu ra -

ti on data« to trans fer and ac ti va te the fil ters. Af -

ter the data is sent the new con fi gu ra ti on is ac ti -

vat ed in the PABX sys tem and any on going In ter -

net con nec ti on is ter mi na ted.

Des crip ti on of the ISDN rou ter functions Firewall