On 2013-01-15, Johan Helsingius <j...@julf.com> wrote: > Peter, > >> :em0 (internal network): >> : inet 172.24.42.254 netmask 0xffffff00 broadcast 172.24.42.255 >> :em2 (wifi sandbox): >> : inet 172.24.42.223 netmask 0xffffffc0 broadcast 172.24.42.255 >> : >> >> You can't do that. > > What specific reason is there that that won't work?
$ ipcalc 172.24.42.223/0xffffffc0 address : 172.24.42.223 netmask : 255.255.255.192 (0xffffffc0) network : 172.24.42.192 /26 broadcast : 172.24.42.255 host min : 172.24.42.193 host max : 172.24.42.254 hosts/net : 62 The 172.24.42.254 address you have on em0 is *inside* the 172.24.42.192/26 network you have on em2. You would need to move that to another address that is in the /24 but outside the /26. Additionally you would need to add a static route on the machines in em0's network so that 172.24.42.192/26 is routed to whatever new address you have for em0 as you have to consider the return path as well as the forward path. Basically: supernetting is tricky, it's best avoided unless there's no other choice - even if you are pretty familiar with networking it's easy to get wrong.
