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Old 13th November 2008
zomo zomo is offline
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Default External Ips

Hello

I have ADSL modem with 4 address on my own use. I am using openbsd and PF and i would like to assign this 4 address to some local hosts. I dont want to use binat. I want to assign public ips to the host behind the server

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Old 13th November 2008
J65nko J65nko is offline
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Configure your OBSD firewall as a transparent bridge, having no IP addresses. Let the hosts use DHCP to get the addresses from the ADSL modem.
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Old 13th November 2008
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There are several possible alternatives that don't use binat, such as:

  • Place your local hosts on a separate Ethernet and NIC, which you bridge with your external NIC:
    Code:
    [internet]---[external NIC]-[OpenBSD]-[NAT addressed private network]
                                      |
                                      |
                             [exposed NIC]
  • A classic dual firewall with DMZ, though typically, the DMZ is on a private subnet with exposed servers and/or ports:
    Code:
    [internet]---[FW1]---{DMZ servers}---[FW2]--{private net}
What's wrong with binat?
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Old 13th November 2008
zomo zomo is offline
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Hi

J65nko but this router is also making nat, queue, and filtering traffic for other computers. Only for few computers i would like to assign this external address... Is there any way ? proxy arp or smth?

PS: I cant add another nic


Thanks for help
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Old 14th November 2008
J65nko J65nko is offline
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There is an example of proxy arp configuration in the arp man page

But I would advise to get another box that you can equip with 3 NICs (external, DMZ and internal)

If you have servers with a public address in your local LAN, those servers, if compromised, can be used to launch an attack against the complete local LAN.

By placing the servers/hosts inside a DMZ these servers still could be compromised, but not used as a base for attacking your internal network.
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Old 14th November 2008
zomo zomo is offline
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Hi !

J65nko, so what if change my ISP and i get from him 2 C class for example xx.xx.xx.1-254 and xx.xx.xy.1-254. Then if i want to assign address to my users i must make binat ?

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Old 14th November 2008
ocicat ocicat is offline
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Quote:
Originally Posted by zomo View Post
...i get from him 2 C class for example xx.xx.xx.1-254 and xx.xx.xy.1-254.
Entire Class C networks are no longer allocated due to address depletion, unless a significant amount of money is exchanged. For home usage, the price would be astronomical, & far from practical.
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Old 14th November 2008
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Ocicat, i am asking about way to assign public ip address for users, without binat, that was only example.

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Old 14th November 2008
J65nko J65nko is offline
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If your users use OpenBSD and have a 'bge' NIC you create a proper "/etc/hostname.bge0" file.
Code:
$cat /etc/hostname.bge0
#dhcp NONE NONE NONE 
inet 192.168.222.20 255.255.255.0 NONE
!ifconfig bge0 media 100baseTX mediaopt full-duplex
See hostname.if(5)

Or you set up a local DHCP server

But I still don't understand why you insist on using public IP addresses
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Old 14th November 2008
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And I don't understand what's wrong with binat, which seems to be a solution designed for this sort of problem.
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Old 19th November 2008
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OK

I tried to make arp proxy wihout any results. I have got from my ISP class with prefix /29, one address is reserved for network, one for modem and one for broadcast, so i have from 8 address 5 for my own use. I divided my class /29 to two class /30. One i leaft on external interface for nat users behind the router and second assigned to internal interface as alias.
like J65nko said, i looked up to the manual for setup arp proxy and i add:

Code:
arp -s 204.1.2.3 00:90:27:bb:cc:dd pub
Computer with assigned ip from second class was unable to connect outside... ? Someone have similiar situation to my, or someone try to use arp proxy on openbsd ?
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Old 19th November 2008
J65nko J65nko is offline
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Unfortunately I am not able to try arp proxy.

My computer lab boxes except one, are still unpacked in the garage. Buying a house and a garden, both unmaintained for more then 3 years, probably is something I shouldn't have done
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Old 20th November 2008
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Ok, someone else try to set it
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