I used to connect to internet through LAN and everything was fine.
Since yesterday the way to connect internet has changed and I automatically obtain IP from dhcp like 172.16.3.102 but if I want to connect to internet I have to call 192.168.100.1. In windows it works finr but in linux I get the following error:
Nov 21 16:36:00 localhost pppd[3195]: pppd 2.4.2 started by root, uid 0
Nov 21 16:36:00 localhost pptp[3196]: anon log[mainptp.c:243]: The synchronous pptp option is NOT activated
Nov 21 16:36:00 localhost pptp[3196]: anon warn[pptp_gre_bindptp_gre.c:95]: connect: Network is unreachable
Nov 21 16:36:00 localhost pptp[3196]: anon fatal[mainptp.c:251]: Cannot bind GRE socket, aborting.
Nov 21 16:36:00 localhost pppd[3195]: Couldn't get channel number: Input/output error
Nov 21 16:36:00 localhost pppd[3195]: Exit.


Any idea?

I write this command whenever I want to connect to internet:
/sbin/ip route add default via 172.16.0.1

but i am getting tired of writing this command all the time.
is there anyway to solve this question?

What does your ifconfig for eth0 look like?

after executing that command it looks like:
eth0 Link encap:Ethernet HWaddr 00:05:5D:1A:6B:1B
inet addr:172.16.1.7 Bcast:172.31.255.255 Mask:255.240.0.0
inet6 addr: fe80::205:5dff:fe1a:6b1b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:57989 errors:0 dropped:0 overruns:0 frame:0
TX packets:896 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4072934 (3.8 MiB) TX bytes:144968 (141.5 KiB)
Interrupt:10 Base address:0xd000

I'm don't quite understand whats going on as both 172.16.3.102 (or 172.16.1.7 in your second posting) and 192.168.100.1 are private network address ranges.

From what i can figure out 192.168.100.1 is your internet gateway address but you won't be able to access this from a 172.16.X.X ip address.

What kind of network is this? Your own, a corporate one or a university?

I would check with the network admin as the gateway address has probably also been changed to a 172.16 address as well.

this is a my dorm's network.
192.168.100.1 is my internet gateway
At first when I execute /sbin/arping -c 1 192.168.100.1 there is no response from it and I whenever I try to connect to internet it says that netwrok is unreachable.
But when I execute /sbin/ip route add default via 172.16.0.1
I can connect to internet but still there s no response from 192.168.100.1
I think 172.16.0.1 is my gateway to server (192.168.100.1)
172.16.3.102 was my previous IP but i think someone esle is using it now so my IP automatically has changed to 172.16.1.7

My IP address is 172.16.4.149
and as I mentioned above 192.168.100.1 is the gateway address which I connect to internet from.
I run this command at first to connect to internet.
/sbin/ip route add default via 172.16.0.1
I have vqcc chat which will not work unitill i run this command so I think there is a problem in ifup or ifdown program.

when I stop the connection i get the following messeage:
restoring routing and DNS configuration
ip route del 192.168.100.1 via 172.16.0.1 dev eth0 src 172.16.4.149
ip route del '172.168.3.0/8' dev 'ppp0'
RTNETLINK answers: Invalid argument

pptpconfig: command failed, exit code 2

and when i try to connect to internet i have to rerun the same command.

I expect that 172.16.0.1 is your gateway on your subnet and 192.168.100.1 is your internet gateway.

It sounds like theres a dhcp conflict(if thats what your running), if possible try disabling routing on the second router.

But hey, atleast your internet works. Thats always a good start.

how to disable routing on the second router?

Well, it depends on what router you have. Heres how I do it on mine.


The default password is admin, leave the user empty.

http://img501.imageshack.us/img501/2...bledhcp5tl.jpg


And if neccessary

http://img501.imageshack.us/img501/3...routing5ad.jpg

I have been working on linux for 9 months but I am still a newbie.
I don't know how to disable routine in fedora core 4. in netwrok configuration there's a route called tab, but there is no router in it. Maybe I need to add a router?

I cannot disable dhcp because my network administrator has forbidden setting IP manualy in my network.
thanks