# pppoe multiple static IP setup



## zealot (Apr 17, 2012)

Good Afternoon Ladies & Gents 

I am having some issues setting up a /30 on a single interface, some of you must be like 'what the hell that's easy' lol, well I though so to*o*. 

So, the way the ISP has told me to set up the statics on the interface is to have them use my main static which is assigned over PPPoE with mpd5 as its default gateway, I'm not doing MLPPP on this line, but I do have a /30 I need to assign to the interface after the first static is assigned auto-magically, now I have setup the routes properly, or so I think. But still none of the IPs are pinging back from a external host. 

[CMD=]route add -net 206.248.xxx.120/30 206.248.xxx.1[/CMD] was the first command I did.

Then I assigned the IPs to the interface with 206.248.xxx.1 as the gateway 

[CMD=]ifconfig ng0 alias 206.248.xxx.121 206.248.xxx.1[/CMD]
[CMD=]ifconfig ng0 alias 206.248.xxx.122 206.248.xxx.1[/CMD]

Now once again I have been told that the gateway for my /30 is supposed to be my main static IP but with this type of setup I'm getting confused with how the routing really works, one would figure that the  /30 has a totally separate gateway then that of the main static  i.e. entirely different net block 

What am I doing wrong with this? do I need some PF rules or something to route  the traffic properly?


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## zealot (Apr 17, 2012)

I solved it. Apparently the ISP is giving me the wrong information 


```
route add -net 206.248.xxx.1x0 206.248.154.1x6
ifconfig ng0 alias 206.248.xxx.1x1 206.248.xxx.1x0
ifconfig ng0 alias 206.248.xxx.1x2 206.248.xxx.1x0
ifconfig ng0 alias 206.248.xxx.1x3 206.248.xxx.1x0
```
and now all IP's are pinging from WAN based hosts.


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## aa (Apr 18, 2012)

*Y*ou'd better set netmask 255.255.255.255 for aliases.


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## zealot (Apr 19, 2012)

I've put the netmask at 255.255.255.252 as its supposed to be


```
Address:   206.248.xxx.xxx       11001110.11111000.10001101.011110 00
Netmask:   255.255.255.252 = 30  11111111.11111111.11111111.111111 00
Wildcard:  0.0.0.3               00000000.00000000.00000000.000000 11
Network:   206.248.xxx.xxx/30    11001110.11111000.10001101.011110 00 (Class C)
Broadcast: 206.248.xxx.xxx       11001110.11111000.10001101.011110 11
HostMin:   206.248.xxx.xxx       11001110.11111000.10001101.011110 01
HostMax:   206.248.xxx.xxx       11001110.11111000.10001101.011110 10
Hosts/Net: 2
```

and the way I'm doing it I can now use my broadcast address as a usable IP.

So 255.255.255.255 would be useless and not really do anything.


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## aa (Apr 19, 2012)

Which one then actually is your broadcast x.x.x.120 or x.x.x.123?

You forgot the important fact that all those in *one interface*, soon arp will get confused. A simple rule of thumb is to set alias IP as their own subnet as well.

But hey, I always open for any impossibility.


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## zealot (Apr 20, 2012)

aa said:
			
		

> Which one then actually is your broadcast x.x.x.120 or x.x.x.123?
> 
> You forgot the important fact that all those in *one interface*, soon arp will get confused. A simple rule of thumb is to set alias IP as their own subnet as well.
> 
> But hey, I always open for any impossibility.




123 is my broadcast, like I said the way I have done it I can use my broadcast as a actual reachable IP, I was told this was only achievable with one2one NAT but this setup proves otherwise. I have not encountered this ARP confusion you speak of though, so I'm kinda wondering if I would be subjected to it at all. Thanks for the reply's friend :e


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