| I manage a few networks with Linux servers and Windows clients, as a number
of the networks are interconnected through machines other than the default
route I have to manage static routes on the Windows client machines. This
on the surface seems easy enough with dhcp, but a couple of the routes use
21 bit masks, and a couple use 26 bit masks. This only seems to be possible
with the versions of dhcpd I am using by adding a code 249 option which requires a hex encoded string for the route(s).
For example to add the route 192.168.20.64/26 through the gateway 192.168.10.62
The following lines need to be added to the dhcpd.conf file
option new-static-routes code 249 = string;
option new-static-routes 1a:c0:a8:14:40:c0:a8:0a:3e;
(I decided to use the name "new-static-routes" for the option as when trying
to figure out how to do this it was in an example listing I found on the web)
When dhcpd has reloaded it's config and a windows client that gets it's ip settings from this server with the address 192.168.10.12, has the
command ipconfig /renew run there will now be the following entry it's
route listing. ( route print or netstat -r -n )
192.168.20.64 255.255.255.192 192.168.10.62 192.168.10.12
Now we come to the reason for this BASH script, I got tired of doing the
conversion of the addresses from decimal to hex in my head, the line above
in decimal is pretty simple: 26:192:168:20:64:192:168:10:62; but my mind
isn't as agile as it used to be so I have trouble remembering that the bit
size comes before the target network, and while I can do the decimal to hex
conversion in my head it takes longer than it used to :(
So I created this script, simply pass it the target and gateway in the form
tt.tt.tt.tt/bb gg.gg.gg.gg and it returns the hex encoded string.
Add a -v before the target and it returns the entire line needed for dhcpd.conf, add another -v and it also give the code 249 line. You can
put as many routes on the line as required (I'm sure there is a limit in
dhcpd or windows, but I don't know what that would be (I haven't hit it
yet))
examples: (Command, Result)
$ hexroute 192.168.20.64/26 192.168.10.62
1a:c0:a8:14:40:c0:a8:0a:3e
$ hexroute -v 192.168.20.64/26 gw 192.168.10.62
option new-static-routes 1a:c0:a8:14:40:c0:a8:0a:3e;
$ hexroute -v -v 192.168.20.64/26 192.168.10.62
# New Option Type for Windows Client Static Routes
option new-static-routes code 249 = string;
option new-static-routes 1a:c0:a8:14:40:c0:a8:0a:3e;
$ hexroute -v 192.168.20.64/26 192.168.10.62 172.16.80.0/21 192.168.10.62
option new-static-routes 1a:c0:a8:14:40:c0:a8:0a:3e:15:ac:10:50:c0:a8:0a:3e;
| 