Access to sub network unreachable.
Craig White
craigwhite at azapple.com
Sat Jan 10 00:58:19 UTC 2009
On Sat, 2009-01-10 at 11:10 +1100, Simon Slater wrote:
> On Fri, 2009-01-09 at 11:58 -0800, Rick Stevens wrote:
> > Robin Laing wrote:
> > > Simon Slater wrote:
> > >> Hi all,
> > >> I'm sure I have missed something simple (or done something
> > >> stupid) but
> > >> have no idea what so I'll ask anyhow.
> > >>
> > >> All the computers on our SOHO network had static addresses in the
> > >> 192.168.0.1-9 range with netmask of 255.255.255.0 and all worked fine
> > >> for ages. Now I have a Linksys gateway which has a default address of
> > >> 192.168.1.1 for configuration. It works fine as a DSL router but I
> > >> cannot use a browser to access the configuration. All I get is "An
> > >> error occurred while loading http://192.168.1.1: Could not connect to
> > >> host." Pinging returns "Destination Host Unreachable".
> > >>
> > >> I changed the netmask for the ethx device to 255.255.0.0 but this
> > >> made
> > >> no difference. What have I forgotten?
> >
> > Odds are that the router also has a netmask of 255.255.255.0 (or a /24).
> > If that's the case, then it can't talk to your client since your client
> > isn't on the router's LAN as far as the router is concerned. Your
> > client can talk to the router with a /16, but the router can't reply to
> > you as it'd try to talk to you over its WAN port. Options:
> >
> > 1. Change all of your client machines to 192.168.1.xxx with netmasks of
> > 255.255.255.0 (/24) to conform to the router's defaults, or
> >
> > 2. Change the netmask on the router to 255.255.0.0 (/16) and all of the
> > client machines to the same, or
> >
> > 3. Change the IP and netmask of the router to 192.168.0.xxx/24 and leave
> > your clients alone.
> >
> > I'd vote for number 3...it makes your new router look like the old
> > router. Remember, though, that if you ever reset your router to the
> > factory defaults, you'll need to change its IP again afterward or
> > you'll be right back here where you started. :-)
> >
> > How to change it? On your client:
> >
> > 1. # ifconfig eth0 192.168.1.whatever netmask 255.255.255.0
> > 2. (browse to 192.168.1.1 and change the IP on the router)
> > 3. # ifconfig eth0 192.168.0.whatever netmask 255.255.255.0 (needed
> > because your router is now on 192.168.0.0/24)
> >
> Thanks everyone for your replies. I think I know where I went wrong
> now: even though the /24 range covers both 192.168.0 and 192.168.1 they
> are separate network segments and won't talk to each other.
>
> I need to read more on addressing and netmasks. Once our half dozen
> boxes were working nicely back in the FC3 days I haven't changed the
> setup since (and probably forgot what little I knew about addressing).
>
> In the next 3 months I'll be adding another half dozen boxes and allow
> for laptops so will be setting up DHCP. The F10 download has just
> finished, so now I might install that first, then follow your advice to
> setup the gateway, then begin experimenting with DHCP.
----
If all systems in 192.168.0 and 192.168.1 networks used 255.255.254.0
subnet mask, they would talk to each other.
Craig
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