Remove the unspecified gateway from linux routing table
Rudy Zijlstra
rudy at grumpydevil.homelinux.org
Tue Feb 17 12:11:45 UTC 2015
Hi Eugene,
See the response from Simon. I am also not familiar with
redhat/centos/Fedora, so no idea where the script will be located. This
script is called by dhclient to do that actual configuration work.
Cheers
Rudy
On 17-02-15 12:44, Eugène Ngontang wrote:
> Hi,
>
> To answer your questions :
> - which distribution is this? / *Fedora 18*
> - is dhcp provided by the a package from the distribution, or is it
> hand compiled? / *Package*
> - which release of dhclient/dhcp is in use? / *Internet Systems
> Consortium DHCP Server V3.0.5-RedHat & nternet Systems Consortium DHCP
> Client 4.2.5*
> - dhclient typically calls a script to set the values. Is this script
> correct and in place? / *Which script are you talking about here? The
> dhclient init script???*
> *
> *
> *I've four other systems with exactly the same configuration and
> connected to same dhcp server, which are working fine.
>
> *
> *
> [PRD][root at hostname]# cat /var/lib/dhclient/dhclient.leases
> lease {
> interface "eth0";
> fixed-address 10.10.10.22;
> option subnet-mask 255.255.255.240;
> option routers 10.10.10.17;
> option dhcp-lease-time 604800;
> option dhcp-message-type 5;
> option domain-name-servers 1.1.2.3,1.2.2.3;
> option dhcp-server-identifier 11.12.254.100;
> option nis-domain "xxx.priv";
> option domain-name "fr.mydomain.org <http://fr.mydomain.org>";
> renew 5 2015/02/20 22:26:22;
> rebind 1 2015/02/23 14:21:26;
> expire 2 2015/02/24 11:21:26;
> }
>
> [PRD][root at hostname]# cat
> /var/lib/dhclient/dhclient-b6a65dbe-6524-4070-b4b7-3cb2b1333187-eth0.lease
> lease {
> interface "eth0";
> fixed-address 10.10.0.22;
> option subnet-mask 255.255.255.240;
> option dhcp-lease-time 604800;
> option routers 10.10.10.17;
> option dhcp-message-type 5;
> option dhcp-server-identifier 11.12.254.100;
> option domain-name-servers 1.1.2.3,1.2.2.3;
> option nis-domain "xxx.priv";
> option domain-name "fr.mydomain.org <http://fr.mydomain.org>";
> renew 4 2015/02/19 14:33:43;
> rebind 0 2015/02/22 15:00:34;
> expire 1 2015/02/23 12:00:34;
> }
> lease {
> interface "eth0";
> fixed-address 10.10.10.22;
> option subnet-mask 255.255.255.240;
> option routers 10.10.10.17;
> option dhcp-lease-time 604800;
> option dhcp-message-type 5;
> option domain-name-servers 1.1.2.3,1.2.2.3;
> option dhcp-server-identifier 10.12.254.100;
> option nis-domain "xxx.priv";
> option domain-name "fr.mydomain.org <http://fr.mydomain.org>";
> renew 4 2015/02/19 17:16:26;
> rebind 0 2015/02/22 16:20:59;
> expire 1 2015/02/23 13:20:59;
> }
>
> [PRD][root at hostname]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
> # Generated by parse-kickstart
> UUID=b6a65dbe-6524-4070-b4b7-3cb2b1333187
> BOOTPROTO=dhcp
> DEVICE=eth0
> ONBOOT=yes
> IPV6INIT=no
> PERSISTENT_DHCLIENT=yes
>
> *
> *Are you seeing anything missing here??? Thanks.*
> *
> *
> *Regards,*
> *Eugène NG*
>
> 2015-02-17 12:16 GMT+01:00 Rudy Zijlstra
> <rudy at grumpydevil.homelinux.org <mailto:rudy at grumpydevil.homelinux.org>>:
>
> Hi Patrick,
>
> I would suggist to find a strong cup of coffee ;)
>
> DHCP is designed to work with no IP routing in place at all.
> Please consider that DHCP provides the computer with the IP
> address it is to use. Any gateway is dependent on that IP address
> and CANNOT be assigned before the IP address is known.
>
> The correct question is indeed posed by the OP, which is why the
> gateway is not applied from the DHCP response.
>
> Some questions:
> - which distribution is this?
> - is dhcp provided by the a package from the distribution, or is
> it hand compiled?
> - which release of dhclient/dhcp is in use?
> - dhclient typically calls a script to set the values. Is this
> script correct and in place?
>
> Cheers
>
>
>
> Rudy
>
>
> On 17-02-15 11:59, Patrick Trapp wrote:
>> Perhaps I am not completely awake yet, but don't you have to have
>> the default gateway in place to have network communication? That
>> is, doesn't it have to precede the DHCP process?
>>
>> It sounds to me like you just need to make the default route
>> persistent so it will survive a reboot. How that is done depends
>> on the flavor of Linux you are running.
>>
>> Patrick
>>
>>
>>
>> On Feb 17, 2015, at 4:43 AM, Eugène Ngontang <sympavali at gmail.com
>> <mailto:sympavali at gmail.com>> wrote:
>>
>>> Hi all,
>>>
>>> I've a remote linux machine whose the routing table is :
>>>
>>> [root at hostname]# route -n
>>> Kernel IP routing table
>>> Destination Gateway Genmask Flags Metric Ref
>>> Use Iface
>>> 0.0.0.0 0.0.0.0 0.0.0.0 U 0 0
>>> 0 eth0
>>> 10.10.10.16 0.0.0.0 255.255.255.240 U 0 0
>>> 0 eth0
>>> 169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0
>>> 0 eth0
>>>
>>> The default gateway I should use is 10.10.10.17, and should be
>>> given by a linux dhcp server. So to be able to connect to the
>>> system I call someone on the site ask him to add the route
>>> manually (**route add default gw 10.10.10.17**).
>>> When the route has been added I can now connect to the system.
>>> And once connected when I check the routing table again I have
>>> this :
>>>
>>> [root at hostname]# route -n
>>> Kernel IP routing table
>>> Destination Gateway Genmask Flags Metric Ref
>>> Use Iface
>>> 0.0.0.0 10.10.10.17 0.0.0.0 UG 0 0
>>> 0 eth0 (UG flag means it's up and is the gateway)
>>> 0.0.0.0 0.0.0.0 0.0.0.0 U 0 0
>>> 0 eth0
>>> 10.10.10.16 0.0.0.0 255.255.255.240 U 0 0
>>> 0 eth0
>>> 169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0
>>> 0 eth0
>>>
>>> And when I restart the system, it boots without the right
>>> default gateway, and I'm obliged to call again to set the route
>>> manually. The dhclient lease file has the good **"option
>>> routers"** taken from the dhcp server.
>>>
>>> Now I'm trying to remove the unspecified route from the routing
>>> table but each time I try I'm disconnected from the machine.
>>>
>>> I've tried these different ways :
>>>
>>> route del -net 0.0.0.0 netmask 0.0.0.0 metric 0
>>>
>>> route del default gw 0.0.0.0
>>>
>>> route del -net 0.0.0.0 gw 0.0.0.0
>>>
>>> The three attempts disconected me from the server, and the guy
>>> at the other side tells me that each time I try to remove the
>>> route the default route becomes a star (**default ***). I'm
>>> obliged to let him add the route again mannualy, and when I'm
>>> connected, and I restart the network I lose the connection again.
>>>
>>> So my questions are :
>>> 1) Why does this unspecified default route come back every time?
>>> 2) How can I (what's the way to) remove it without spoiling the
>>> routing table (losing the good default gateway).
>>>
>>> Thanks.
>>>
>>> Regards,
>>> Eugène NG
>>>
>>>
>>>
>>> --
>>> ngonta_e at epitech.net <mailto:ngonta_e at epitech.net>
>>> sympavali at gmail.com <mailto:sympavali at gmail.com>
>>> ------------------------------------------------------------
>>> /*Aux hommes il faut un chef, et au*//* chef il faut des hommes!
>>> L'habit ne fait pas le moine, mais lorsqu'on te voit on te juge!
>>> */
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>>
>>
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>
> --
> ngonta_e at epitech.net <mailto:ngonta_e at epitech.net>
> sympavali at gmail.com <mailto:sympavali at gmail.com>
> ------------------------------------------------------------
> /*Aux hommes il faut un chef, et au*//* chef il faut des hommes!
> L'habit ne fait pas le moine, mais lorsqu'on te voit on te juge!
> */
>
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