Can't access internet on HDR after changing network address

[prpr]

Without a packet dump we will never know.
FWIW, my wireless connected unit sometimes has similar trouble. It works fine on the LAN and I can get to it over the VPN, but it can't see anything else e.g. the package server.
Looking at the routing table I see a spurious entry for 192.0.2.100 on the wlan0 interface (as well as its normal IP address host entry and gateway entry). This isn't there when the box is working. A restart fixes it but I've no idea what causes it.
Attempts to delete this route (even if I can remember the syntax, 'cos the stupid Busybox module doesn't display it) always cause it to lock up.

 

[Black Hole]

IIRC 192.0.2.100 is the default IP address if the unit boots without a manually assigned or DHCP allocated IP address.

 

[prpr]

IIRC 192.0.2.100 is the default IP address if the unit boots without a manually assigned or DHCP allocated IP address.

Well, yes, I know that, but why/how does it get left in there and screw things up further down the line?...

 

[Black Hole]

Without a packet dump we will never know.

As you seem to be genned up on protocols, perhaps you know whether the Humax has to do anything special before a non-local-network ping can reach out through the router, or if the Humax just puts the ping packet onto the network and the router is entirely responsible for sending it out?

 

[Black Hole]

Well, yes, I know that, but why/how does it get left in there and screw things up further down the line?...

Sorry, I only made the comment in case other readers had not spotted the connection. It's not like 192.0.2.100 is a completely random number; if any IP address is likely to get "left around" that one is (but IIRC the default address for wireless is 192.0.2.200, and .100 is for wired LAN).

Your symptoms seem very similar the OP's.

 

[Owen Smith]

As you seem to be genned up on protocols, perhaps you know whether the Humax has to do anything special before a non-local-network ping can reach out through the router, or if the Humax just puts the ping packet onto the network and the router is entirely responsible for sending it out?

Like all other IP stacks, the Humax knows that the address is not on the local IP subnet so sends it to the relevant IP gateway, im this case the default simce there is only one. Them it ARPs to get the gateways's ethernet address to send it there, the same as it would for a local address. The only difference is "ah, this is not local, I need to send it to the gateway" which is why I posted the results of route -n.

 

[prpr]

the Humax knows that the address is not on the local IP subnet

For BH's benefit: Source address & Netmask != Destination address & Netmask

 

[Black Hole]

At least I knew that much!

As the Humax seems to be involved in the decision to send the ping to the gateway address, I suppose that points the finger. Thanks for the clarifications.

 

[Owen Smith]

At least I knew that much!

As the Humax seems to be involved in the decision to send the ping to the gateway address, I suppose that points the finger. Thanks for the clarifications.

Indeed. I was able to ping the gateway's address on the local subnet from the Humax. And other computers on my network could ping things like www.google.com so the gateway was definitely working. The only conclusion I can draw is that that Humax was not sending the external address pings to the gateway.