Blocking appletalk, and multicast packets on an Ascend Pipeline

Документ взят из кэша поисковой машины. Адрес оригинального документа : http://hea-www.harvard.edu/~fine/ISDN/p25filters.html
Дата изменения: Unknown
Дата индексирования: Sun Apr 10 07:00:25 2016
Кодировка:
Поисковые слова: m 81

I use a Pipeline 25 at my house to connect to work (OSU). My "network" at home consists of a Sun SS1+, the Pipeline, a print server, and sometimes, an Apple Powerbook 3400. I have CAP (Columbia Appletalk Package) installed, so that I can print from the Powerbook to the lpd-driven printer, and so that I can share files easily with the Sun. (I think MacOS8 or 8.1 supports lpd), and the newer TCP/IP-based file sharing is supposed to be easier to deal with too, but I already had CAP set up, so it was the easiest route).

I want access to work, and to the internet, but I want my appletalk network to be my own personal home network. So I want to block appletalk packets. (The call filter that comes with the Pipeline 25 doesn't block any packets at all. It is for people who use Ethertalk, and want to bridge it, but don't want to place ISDN calls based on random or incidental Ethertalk traffic.) The filter to block all Ethertalk packets is much simpler than the Call filter.

Block Appletalk                 #this is what I named the filter
  Output
    01 Generic                  #don't forward appletalk packets
      Forward=No
      Offset=14
      Length=8 
      Mask=ffffff000000ffff
      Value=aaaa03000000809b    #809b is appletalk ethernet proto number
      More=No 
    02 Generic                  #don't forward appletalk AARP packets
      Forward=No
      Offset=14
      Length=8
      Mask=ffffff000000ffff
      Value=aaaa0300000080f3    #80f3 is appletalk AARP ethernet proto number
      More=No
    03 Generic                  #forward everything else
      Forward=Yes
      Offset=0
      Length=0
      Mask=0000000000000000
      Value=0000000000000000
      More=No

I've also had problems where Mbone traffic on the OSU end of the line has flooded my ISDN line. The following filter is used on the OSU end (on a Pipeline 50), to block this traffic, as well as hide campus Ethertalk from my network.

  Output
    01 IP                         #block multicast packets
      Forward=No
      Src Mask=0.0.0.0
      Src Adrs=0.0.0.0
      Dst Mask=255.0.0.0
      Dst Adrs=224.0.0.0          #all multicast addresses start with 224
      Protocol=0
      Src Port Cmp=None
      Src Port #=N/A
      Dst Port Cmp=None
      Dst Port #=N/A
      TCP Estab=N/A
    02 Generic                    #the rest is the same as the P25 filter
      Forward=No
      Offset=14 
      Length=8 
      Mask=ffffff000000ffff
      Value=aaaa03000000809b
      More=No
    03 Generic
      Forward=No
      Offset=14  
      Length=8
      Mask=ffffff000000ffff
      Value=aaaa0300000080f3
      More=No
    04 Generic
      Forward=Yes
      Offset=0
      Length=0
      Mask=0000000000000000
      Value=0000000000000000
      More=No

The Ascend FAQ has a good reference that lists well known IP port numbers, IP protocol numbers, and Ethernet protocol numbers.

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