[CentOS] Forgetting network settings

Rohan Gilchrist rohan at gilchrist.me
Mon Mar 29 14:57:20 UTC 2010


So you're saying that your default gateway is an IP address that's part of a *different* network/subnet?

I don't know how this network has been designed, but typically I would expect that your default gateway would be something like

188.72.255.1

rather than 217.20.117.1 that you've mentioned earlier.

Take a look at mine for example:

[~]ifconfig
eth0      Link encap:Ethernet  HWaddr FE:FD:6D:4A:C1:69
           inet addr:109.xx.xxx.105  Bcast:109.74.193.255  Mask:255.255.255.0
           inet6 addr: fe80::fcfd:6dff:fe4a:c169/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:78742 errors:0 dropped:0 overruns:0 frame:0
           TX packets:67114 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:35442733 (33.8 MiB)  TX bytes:12607832 (12.0 MiB)

lo        Link encap:Local Loopback
           inet addr:127.0.0.1  Mask:255.0.0.0
           inet6 addr: ::1/128 Scope:Host
           UP LOOPBACK RUNNING  MTU:16436  Metric:1
           RX packets:8292 errors:0 dropped:0 overruns:0 frame:0
           TX packets:8292 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:1195297 (1.1 MiB)  TX bytes:1195297 (1.1 MiB)

[~]netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
109.xx.xxx.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
0.0.0.0         109.xx.xxx.1    0.0.0.0         UG        0 0          0 eth0

So you can see my host has .105 assigned to eth0, and the default gateway is .1 of the same network/subnet.

You might want to check that your addressing is correct.



On Mon, 29 Mar 2010, cahit Eyig?nl? wrote:

> there is no problem with my internet connection i just want that to do this cent os automatically :route add default gw 217.20.117.1 
> before typing this my netstat -rn looks like this :
> root at lin3 [~]# netstat -rn (that is not able to connect to internet)
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
> 217.20.117.1    0.0.0.0         255.255.255.255 UH        0 0          0 eth0
> 188.72.255.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0
> 169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
> after adding gateway : (this works perfect)
> root at lin3 [~]# netstat -rn
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
> 217.20.117.1    0.0.0.0         255.255.255.255 UH        0 0          0 eth0
> 188.72.255.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0
> 169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
> 0.0.0.0         217.20.117.1    0.0.0.0         UG        0 0          0 eth0 
> 
> i just want to add bold line automatically
> 
> and this is my ifconfig :
> root at lin3 [~]# ifconfig -a
> eth0      Link encap:Ethernet  HWaddr 00:0C:29:83:21:44
>           inet addr:188.72.255.189  Bcast:188.72.255.255  Mask:255.255.255.0
>           inet6 addr: fe80::20c:29ff:fe83:2144/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:9653 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:458 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:876648 (856.1 KiB)  TX bytes:50814 (49.6 KiB)
>           Base address:0x2000 Memory:d8920000-d8940000
> 
> lo        Link encap:Local Loopback
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           inet6 addr: ::1/128 Scope:Host
>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>           RX packets:483 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:483 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:75305 (73.5 KiB)  TX bytes:75305 (73.5 KiB)
> 
> sit0      Link encap:IPv6-in-IPv4
>           NOARP  MTU:1480  Metric:1
>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
> 
> 
> 
> 2010/3/29 Matt Iavarone <matt.iavarone at gmail.com>
>       2010/3/29 cahit Eyig?nl? <cahit.eyigunlu at gmail.com>:
> > This is my two line on route-eth0
> >  address0=217.20.117.1
> >  subnet0=255.255.255.255
> > but what should be next line for default gateway the only thing that i could
> > not complete is default gateway setting
> > and my netstat table must looklike this :
> > Destination     Gateway         Genmask         Flags   MSS Window  irtt
> > Iface
> > 217.20.117.1    0.0.0.0         255.255.255.255 UH        0 0          0
> > eth0
> > xx.xx.xx.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
> > 0.0.0.0         217.20.117.1    0.0.0.0         UG        0 0          0
> > eth0
> > and now i see only the first two line truely i am adding 3rd line on every
> > time restart manually with route add default gw
> >
> > 2010/3/29 Les Mikesell <lesmikesell at gmail.com>
> >>
> >> cahit Eyig?nl? wrote:
> >> > i am reaching the network with this :
> >> > route add -net 217.20.117.1 netmask 255.255.255.255 dev eth0
> >> > route add default gw 217.20.117.1
> >> >
> >> > i have added eth0
> >> > address0=217.20.117.1
> >> > subnet0=255.255.255.255
> >> >
> >> > the first command is ok but how could i set the second command to cent
> >> > os to do it automatically
> >> >
> >>
> >> If you create a file named /etc/sysconfig/network-scripts/route-eth0 you
> >> can put
> >> lines in it that will have 'ip route' added at the beginning and executed
> >> after
> >> the interface is up.  "ip route" takes some different arguments than the
> >> "route"
> >> command - see "man ip" for details.
> >>
> >> --
> >>   Les Mikesell
> >>   lesmikesell at gmail.com
> >>
> >>
> >>
> >> _______________________________________________
> >> CentOS mailing list
> >> CentOS at centos.org
> >> http://lists.centos.org/mailman/listinfo/centos
> >
> >
> > _______________________________________________
> > CentOS mailing list
> > CentOS at centos.org
> > http://lists.centos.org/mailman/listinfo/centos
> >
> >
> 
> Why don't you post the results of 'ifconfig -a' and 'ip route show'?
> Giving information piecemeal is not helping anyone.
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> 
> 
> 
>


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