5:52 a.m.
I checked my hosts file and it is empty. I copied from another PC
changing the name of computer, I re-booted and it is still empty!!!
What shall I check???
--
Antonio Montagnani
Skype : antoniomontag
11:05 a.m.
On Thu, 2007-10-11 at 12:52 +0200, antonio montagnani wrote:
I checked my hosts file and it is empty. I copied from another PC
changing the name of computer, I re-booted and it is still empty!!!
What shall I check???
"/etc/hosts"?
Is your interface handled by DHCP? It can re-write the hosts file, you
might want to make your changes while disconnected.
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4:07 p.m.
2007/10/11, Tim <ignored_mailbox(a)yahoo.com.au>:
On Thu, 2007-10-11 at 12:52 +0200, antonio montagnani wrote:
> I checked my hosts file and it is empty. I copied from another PC
> changing the name of computer, I re-booted and it is still empty!!!
> What shall I check???
"/etc/hosts"?
Is your interface handled by DHCP? It can re-write the hosts file, you
might want to make your changes while disconnected.
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Why should a Dynamic address re-write my hosts file??? in this case
blankening it??
Any technical reason or is it a bug??? When host file is empty,
logging in not cable connected is extremely long.....
--
Antonio Montagnani
Skype : antoniomontag
12:37 a.m.
Tim:
> Is your interface handled by DHCP? It can re-write the hosts
file,
> you might want to make your changes while disconnected.
antonio montagnani:
Why should a Dynamic address re-write my hosts file??? in this case
blankening it??
Any technical reason or is it a bug??? When host file is empty,
logging in not cable connected is extremely long.....
That's why I suggested correcting it when the DHCP client hasn't changed
it. That way, that should be your default. The DCHP client may change
it when it wants to, then revert it afterwards.
I can think of one reason why it might do that sort of thing: So that
your networking has the addresses it needs to use when there's no local
DNS server to provide the answers.
I also found DHCP to rewrite my /etc/resolv.conf file, if it wanted to
add DNS servers. But it's a long time since I looked into that.
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3:59 p.m.
On Fri, 2007-10-12 at 15:07 +0930, Tim wrote:
Tim:
>> Is your interface handled by DHCP? It can re-write the hosts file,
>> you might want to make your changes while disconnected.
antonio montagnani:
> Why should a Dynamic address re-write my hosts file??? in this case
> blankening it??
>
> Any technical reason or is it a bug??? When host file is empty,
> logging in not cable connected is extremely long.....
That's why I suggested correcting it when the DHCP client hasn't changed
it. That way, that should be your default. The DCHP client may change
it when it wants to, then revert it afterwards.
I can think of one reason why it might do that sort of thing: So that
your networking has the addresses it needs to use when there's no local
DNS server to provide the answers.
I also found DHCP to rewrite my /etc/resolv.conf file, if it wanted to
add DNS servers. But it's a long time since I looked into that.
DNS rewriting
the hosts file is just plain screwy. In my mind there is something
very wrong with the DNS server.
=======================================================================
Did you ever walk into a room and forget why you walked in? I think
that's how dogs spend their lives. -- Sue Murphy
=======================================================================
Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam(a)sbcglobal.net
4:28 p.m.
On Fri, 2007-10-12 at 15:59 -0500, Aaron Konstam wrote:
DNS rewriting the hosts file is just plain screwy. In my mind there
is
something very wrong with the DNS server.
DHCP changing the hosts file, not DNS... The DHCP server can specify
quite a few things to change, some on your computer, some on the local
DNS server (to add your computer to the records).
Why? I'm glad you asked! DHCP is useful for when person A takes their
computer B to network C today, then goes home and plugs it into network
D, and takes it with them to the hotel network E, all of which have
wildly different parameters, and needs change to all manner of things:
Your DNS servers.
Your IP address.
Your hostname.
Your gateway address.
Other server addresses...
--
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6:07 p.m.
Tim wrote:
On Fri, 2007-10-12 at 15:59 -0500, Aaron Konstam wrote:
> DNS rewriting the hosts file is just plain screwy. In my mind there is
> something very wrong with the DNS server.
DHCP changing the hosts file, not DNS... The DHCP server can specify
quite a few things to change, some on your computer, some on the local
DNS server (to add your computer to the records).
Why? I'm glad you asked! DHCP is useful for when person A takes their
computer B to network C today, then goes home and plugs it into network
D, and takes it with them to the hotel network E, all of which have
wildly different parameters, and needs change to all manner of things:
However, this only makes sense if all networks rewrite all the same data.
If network D doesn't write out the hosts file that is needed for that
network and the computer is taken to network E and the hosts file for D is
wiped out....I think I've be rather miffed when I returned my system to
network D.
Your DNS servers.
Your IP address.
Your hostname.
Your gateway address.
Other server addresses...
--
You can't cheat the phone company.
6:45 p.m.
Tim:
> DHCP changing the hosts file, not DNS... The DHCP server can
specify
> quite a few things to change, some on your computer, some on the local
> DNS server (to add your computer to the records).
>
> Why? I'm glad you asked! DHCP is useful for when person A takes their
> computer B to network C today, then goes home and plugs it into network
> D, and takes it with them to the hotel network E, all of which have
> wildly different parameters, and needs change to all manner of things:
Ed Greshko:
However, this only makes sense if all networks rewrite all the same
data. If network D doesn't write out the hosts file that is needed for
that network and the computer is taken to network E and the hosts file
for D is wiped out....I think I've be rather miffed when I returned my
system to network D.
It's more a case of your client starting out with it's stand-alone
configuration. Backing that up when it changes it to suit one network,
and restoring it upon disconnection (your client changing its
configuration based on what the DHCP server provides, not the remote
DHCP server actually changing things on the client). And doing the same
sort of thing for the next network.
Automatically doing the sorts of things that you'd have done by hand.
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7:29 p.m.
Tim wrote:
Tim:
>> DHCP changing the hosts file, not DNS... The DHCP server can specify
>> quite a few things to change, some on your computer, some on the local
>> DNS server (to add your computer to the records).
>>
>> Why? I'm glad you asked! DHCP is useful for when person A takes their
>> computer B to network C today, then goes home and plugs it into network
>> D, and takes it with them to the hotel network E, all of which have
>> wildly different parameters, and needs change to all manner of things:
Ed Greshko:
> However, this only makes sense if all networks rewrite all the same
> data. If network D doesn't write out the hosts file that is needed for
> that network and the computer is taken to network E and the hosts file
> for D is wiped out....I think I've be rather miffed when I returned my
> system to network D.
It's more a case of your client starting out with it's stand-alone
configuration. Backing that up when it changes it to suit one network,
and restoring it upon disconnection (your client changing its
configuration based on what the DHCP server provides, not the remote
DHCP server actually changing things on the client). And doing the same
sort of thing for the next network.
Automatically doing the sorts of things that you'd have done by hand.
But, having things done automatically when you are unaware they are going to
be done is never helpful, IMHO. In this case, if indeed the hosts file is
being overwritten by DHCP, it is certainly not what the OP anticipated or
wanted since he is left with a blank hosts file.
2:04 a.m.
On Sat, 2007-10-13 at 08:29 +0800, Ed Greshko wrote:
But, having things done automatically when you are unaware they are
going to be done is never helpful, IMHO.
Yes, and no... If it works, and the user wouldn't have been able to
figure things out, it would have been helpful to them. Which tends to
be the point of things like DHCP, network manager, and so on...
In this case, if indeed the hosts file is being overwritten by DHCP,
it is certainly not what the OP anticipated or wanted since he is left
with a blank hosts file.
Though, I'd say that's a fault condition.
The sorts of things that a DHCP client can and can't do are user
configurable, by customising "/etc/dhclient.conf".
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6:37 a.m.
On Sat, 2007-10-13 at 16:34 +0930, Tim wrote:
On Sat, 2007-10-13 at 08:29 +0800, Ed Greshko wrote:
>
> But, having things done automatically when you are unaware they are
> going to be done is never helpful, IMHO.
Yes, and no... If it works, and the user wouldn't have been able to
figure things out, it would have been helpful to them. Which tends to
be the point of things like DHCP, network manager, and so on...
> In this case, if indeed the hosts file is being overwritten by DHCP,
> it is certainly not what the OP anticipated or wanted since he is left
> with a blank hosts file.
Though, I'd say that's a fault condition.
The sorts of things that a DHCP client can and can't do are user
configurable, by customising "/etc/dhclient.conf"
You have it sort of backwards. /etc/dhclient.conf tells the DHCP server
what the client wants it do do. It does not determine what the DHCP
server is allowed to do on its own volition. If the file is empty and it
is on my client the hosts file should,d be untouched.
Quickly looking at the man page for that file I see no provision for the
host file to be changed but maybe it is too early in the morning.
--
=======================================================================
It's recently come to Fortune's attention that scientists have stopped
using laboratory rats in favor of attorneys. Seems that there are not
only more of them, but you don't get so emotionally attached. The only
difficulty is that it's sometimes difficult to apply the experimental
results to humans. [Also, there are some things even a rat won't do.
Ed.]
=======================================================================
Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam(a)sbcglobal.net
1:44 p.m.
Tim:
> The sorts of things that a DHCP client can and can't do are
user
> configurable, by customising "/etc/dhclient.conf">
Aaron Konstam
You have it sort of backwards. /etc/dhclient.conf tells the DHCP
server
what the client wants it do do. It does not determine what the DHCP
server is allowed to do on its own volition.
It determines what your client asks of the server, and what attention it
pays to what the server tells it. Yes, it doesn't change how the server
behaves, it changes how the client reacts. You can set your client not
to ask for name servers, set it to include some addresses of your own in
addition to the server, and so on.
If the file is empty and it is on my client the hosts file should,d
be
untouched.
That would depend on the defaults. The defaults would, most likely, be
to do everything that the DHCP server tells you to.
--
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important to the thread.)
Don't send private replies to my address, the mailbox is ignored.
I read messages from the public lists.
3:21 p.m.
On Sun, 2007-10-14 at 04:14 +0930, Tim wrote:
Tim:
>> The sorts of things that a DHCP client can and can't do are user
>> configurable, by customising "/etc/dhclient.conf">
Aaron Konstam
> You have it sort of backwards. /etc/dhclient.conf tells the DHCP server
> what the client wants it do do. It does not determine what the DHCP
> server is allowed to do on its own volition.
It determines what your client asks of the server, and what attention it
pays to what the server tells it. Yes, it doesn't change how the server
behaves, it changes how the client reacts. You can set your client not
to ask for name servers, set it to include some addresses of your own in
addition to the server, and so on.
> If the file is empty and it is on my client the hosts file should,d be
> untouched.
That would depend on the defaults. The defaults would, most likely, be
to do everything that the DHCP server tells you to.
We are getting nowhere. Have you ever experiences an instance when the DHCP has changed
the hosts file so that its previous contents are erased?
--
=======================================================================
In most countries selling harmful things like drugs is punishable. Then
howcome people can sell Microsoft software and go unpunished? (By
hasku(a)rost.abo.fi, Hasse Skrifvars)
=======================================================================
Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam(a)sbcglobal.net
6:04 p.m.
Tim wrote:
> If the file is empty and it is on my client the hosts file
should,d be
> untouched.
That would depend on the defaults. The defaults would, most likely, be
to do everything that the DHCP server tells you to.
Last time I looked, the default was to do very little. Basically, set
IP, netmask, broadcast, router and DNS. It would be useful to set the
mail gateway and some other stuff, but I've not seen any distro do so.
--
Cheers
John
-- spambait
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6:02 p.m.
Aaron Konstam wrote:
On Sat, 2007-10-13 at 16:34 +0930, Tim wrote:
> On Sat, 2007-10-13 at 08:29 +0800, Ed Greshko wrote:
>> But, having things done automatically when you are unaware they are
>> going to be done is never helpful, IMHO.
> Yes, and no... If it works, and the user wouldn't have been able to
> figure things out, it would have been helpful to them. Which tends to
> be the point of things like DHCP, network manager, and so on...
>
>> In this case, if indeed the hosts file is being overwritten by DHCP,
>> it is certainly not what the OP anticipated or wanted since he is left
>> with a blank hosts file.
> Though, I'd say that's a fault condition.
>
> The sorts of things that a DHCP client can and can't do are user
> configurable, by customising "/etc/dhclient.conf"
>
You have it sort of backwards. /etc/dhclient.conf tells the DHCP server
what the client wants it do do. It does not determine what the DHCP
server is allowed to do on its own volition. If the file is empty and it
is on my client the hosts file should,d be untouched.
Quickly looking at the man page for that file I see no provision for the
host file to be changed but maybe it is too early in the morning.
dhcp clients can be configured to ask for particular information, and
dhcp servers can be configured to provide particular information.
If all goes well, the dhcp server will provide all the information the
client asks for, but the client is under no obligation to use all the
information the server provides.
Documentation commonly available on how to configure ISC DHCPD3 to
support PXE booting for (eg) network installs generally omits to mention
how to provide that information only to a PXE BIOS. Mostly clients
ignore next-server and filename and any other information they don't want.
How some of that information might get into /etc/hosts depends on the
scripts supporting the DHCP client. Use rpm to list the files in your
dhcp client package, and peruse anything in /etc or any [s]bin
directory, and the documentation for hints.
How it's done depends on the actual dhcp client (common ones in Linux
are dhcpd and dhclient, and I'm a bit confused about who provides which
and in which releases). I've configured a laptop (originally running FC3
but upgraded to FC5 or so) to use the provided DNS servers to
reconfigure bind and restart it, but the particulars of that technique
don't work with SUSE's equivalent package.
It would be interesting to see OP's /etc/hosts file before and after
it's updated: that may provide some clue as to what's happening. I'm
guessing it gets an entry like this:
192.168.9.131 numbat.demo.lan numbat
which wouldn't do me any harm, but wouldn't help anyone else find numbat.
There might be a comment that provides a clue.
--
Cheers
John
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6:22 a.m.
On Sat, 2007-10-13 at 06:58 +0930, Tim wrote:
On Fri, 2007-10-12 at 15:59 -0500, Aaron Konstam wrote:
> DNS rewriting the hosts file is just plain screwy. In my mind there is
> something very wrong with the DNS server.
DHCP changing the hosts file, not DNS... The DHCP server can specify
quite a few things to change, some on your computer, some on the local
DNS server (to add your computer to the records).
Why? I'm glad you asked! DHCP is useful for when person A takes their
computer B to network C today, then goes home and plugs it into network
D, and takes it with them to the hotel network E, all of which have
wildly different parameters, and needs change to all manner of things:
Your DNS servers.
Your IP address.
Your hostname.
Your gateway address.
Other server addresses...
When you are right you are right. I meant DHCP not DNS.
But you reason
for changing the host file makes no sense to me. TThe hostname yes but
not the hosts file. The hosts file contains machine names you will use
for outbound traffic and that should remain unchanged.
=======================================================================
Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam(a)sbcglobal.net
1:48 p.m.
On Sat, 2007-10-13 at 06:22 -0500, Aaron Konstam wrote:
But you reason for changing the host file makes no sense to me. TThe
hostname yes but not the hosts file. The hosts file contains machine
names you will use for outbound traffic and that should remain
unchanged.
The hosts file does *more* than that, that's why you're not seeing the
reason.
The machine can also use it to work out its own addresses. A DHCP
server can change YOUR addresses, and hostname. Modifying the hosts
file and resolv.conf file, amongst other files that could be changed,
*can* be done to ensure that your machine can work its own addresses
out, without needing an external DNS server.
A DHCP server can also tell you other addresses to use, such as NTP,
NNTP, SMTP servers, and so on. Those addresses could also be added to a
hosts file, dynamically, if it were to be beneficial.
--
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important to the thread.)
Don't send private replies to my address, the mailbox is ignored.
I read messages from the public lists.
2:34 p.m.
2007/10/13, Tim <ignored_mailbox(a)yahoo.com.au>:
On Sat, 2007-10-13 at 06:22 -0500, Aaron Konstam wrote:
> But you reason for changing the host file makes no sense to me. TThe
> hostname yes but not the hosts file. The hosts file contains machine
> names you will use for outbound traffic and that should remain
> unchanged.
The hosts file does *more* than that, that's why you're not seeing the
reason.
The machine can also use it to work out its own addresses. A DHCP
server can change YOUR addresses, and hostname. Modifying the hosts
file and resolv.conf file, amongst other files that could be changed,
*can* be done to ensure that your machine can work its own addresses
out, without needing an external DNS server.
A DHCP server can also tell you other addresses to use, such as NTP,
NNTP, SMTP servers, and so on. Those addresses could also be added to a
hosts file, dynamically, if it were to be beneficial.
--
(This box runs FC7, my others run FC4, FC5 & FC6, in case that's
important to the thread.)
Don't send private replies to my address, the mailbox is ignored.
I read messages from the public lists.
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I am learning a lot from this thread.
I have only one question: if hosts file can be emptied by any DHCP
server (maybe what happened in my case, I can't check because my
server is sleeping in the office until monday...), I don' understand
why an empty file can prevent from logging into the machine (that is
what I experienced on my laptop..)
--
Antonio Montagnani
Skype : antoniomontag
3:19 p.m.
On Sat, 2007-10-13 at 21:34 +0200, antonio montagnani wrote:
2007/10/13, Tim <ignored_mailbox(a)yahoo.com.au>:
> On Sat, 2007-10-13 at 06:22 -0500, Aaron Konstam wrote:
> > But you reason for changing the host file makes no sense to me. TThe
> > hostname yes but not the hosts file. The hosts file contains machine
> > names you will use for outbound traffic and that should remain
> > unchanged.
>
> The hosts file does *more* than that, that's why you're not seeing the
> reason.
>
> The machine can also use it to work out its own addresses. A DHCP
> server can change YOUR addresses, and hostname. Modifying the hosts
> file and resolv.conf file, amongst other files that could be changed,
> *can* be done to ensure that your machine can work its own addresses
> out, without needing an external DNS server.
>
> A DHCP server can also tell you other addresses to use, such as NTP,
> NNTP, SMTP servers, and so on. Those addresses could also be added to a
> hosts file, dynamically, if it were to be beneficial.
>
> --
> (This box runs FC7, my others run FC4, FC5 & FC6, in case that's
> important to the thread.)
>
> Don't send private replies to my address, the mailbox is ignored.
> I read messages from the public lists.
>
>
> --
> fedora-list mailing list
> fedora-list(a)redhat.com
> To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
>
I am learning a lot from this thread.
I have only one question: if hosts file can be emptied by any DHCP
server (maybe what happened in my case, I can't check because my
server is sleeping in the office until monday...), I don' understand
why an empty file can prevent from logging into the machine (that is
what I experienced on my laptop..)
--
I suspect because login in requires at least a definition of localhost
in the hosts file.
--
=======================================================================
The fountain code has been tightened slightly so you can no longer dip
objects into a fountain or drink from one while you are floating in
mid-air due to levitation. Teleporting to hell via a teleportation trap
will no longer occur if the character does not have fire resistance. -
README file from the NetHack game
=======================================================================
Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam(a)sbcglobal.net
6:26 a.m.
On Sat, 2007-10-13 at 06:58 +0930, Tim wrote:
On Fri, 2007-10-12 at 15:59 -0500, Aaron Konstam wrote:
> DNS rewriting the hosts file is just plain screwy. In my mind there is
> something very wrong with the DNS server.
DHCP changing the hosts file, not DNS... The DHCP server can specify
quite a few things to change, some on your computer, some on the local
DNS server (to add your computer to the records).
Why? I'm glad you asked! DHCP is useful for when person A takes their
computer B to network C today, then goes home and plugs it into network
D, and takes it with them to the hotel network E, all of which have
wildly different parameters, and needs change to all manner of things:
Your DNS servers.
Your IP address.
Your hostname.
Your gateway address.
Other server addresses...
You are right . I meant DHCP not DNS. But I still see no
reason for DHCP
to change your hosts file. hostname yes but the machine names in the
hosts file are used for outbound traffic and should not be changed.
--
=======================================================================
Q: What do you call a half-dozen Indians with Asian flu? A: Six sick
Sikhs (sic).
=======================================================================
Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam(a)sbcglobal.net
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days inactive
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19 comments
5 participants
participants (5)
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Tim