routing, was: Re: <blank subject>

Charles Swiger cswiger at
Sat Dec 6 11:44:23 PST 2003

Hi, Liquid--

On Dec 6, 2003, at 3:06 AM, liquid at wrote:
> I'm going to have a static IP - say xx.xx.yy.zz - and a subnet as 
> follows:
> xx.xx.xx.zz/28

Do you mean, "I am switching from a single static IP to a 16-address 
subnet", or are you going to have both a static IP on one connection 
AND a /28 subnet over a second connection?

> 1.  Do I need to inform the ISP of my intentions so that people can 
> actually
> connect to an IP which is part of my subnet, but behind this router I 
> intend
> to build? (I didn't think it was necessary until I read 19.2.5 in the
> handbook - it doesn't seem like it's necessary based on that alone, 
> but it
> has placed some doubt in my mind).

No, your ISP will route IP traffic for the subnet to you.  On the other 
hand, certainly you should talk to your ISP about your network topology 
if you have any specific issues or questions for them.

> 2.  I currently run my FreeBSD router on a cable connection while 
> waiting
> for the new ISP to get setup.  I use NAT to translate the EXT. IP to 
> the
> internal ones of my lan.  I don't need to run nat for the setup I plan 
> to
> have do I?

No, you don't need NAT for IPs on your new subnet: they are "directly 
Internet routable" if you want a buzzword.  :-)  However, you should 
spend some time considering security and setting up a firewall.

Sometime later, you might want to consider how to have machines on your 
new network be able to fail-over to your single-IP connection; and one 
way of doing so would be to use a NAT gateway of your public IPs from 
the /28 subnet via your original connection.  [The inverse of 

> 3.  Finally, I've read (briefly thus far) about routed on FreeBSD.  
> Would
> this daemon be used in such a way that I don't even need to add static
> routes for LAN?

Yes, but routed is really intended for dynamic routing within an 
intranet, and is overkill for your situation.  Specificly, you would 
accomplish more by configuring DHCP on your FreeBSD machine and 
broadcasting the correct default router IP than you would gain by using 

Ping all of your machines (or use the subnet broadcast address), and do 
an "arp -a" to get MAC addrs, then set up host sections to allocate 
static IPs via DHCP, so your machines can all be network 
auto-configured even if you rebuild/reinstall the OS on a particular 

> Again, this address is not subscribed, so please answer by putting my
> address in the cc: field.



More information about the freebsd-questions mailing list