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Re: Access to sub network unreachable.



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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