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Old 10-06-2012, 03:56 AM
Stan Hoeppner
 
Default dynamic IP assignment on servers = brain damage

This thread reinforces what experienced server admins round the world
have known forever:

DO NOT USE dynamic network address assignment on servers.

The problem in this thread is but one of many that can/will result from
using dynamic IP assignment with servers. If the OP had mentioned his
use of dynamic IP up front he would have saved himself, and the rest of
us, much time.

--
Stan


On 10/5/2012 11:42 AM, Satoru Otsubo wrote:
> Hi,
> I'm initiator of this thread.
>
>> On Thu, Oct 04, 2012 at 04:53:23AM +0900, Satoru Otsubo wrote:
>>> Syntax error on line 2 of /etc/apache2/ports.conf
>>
>> What about this syntax error?
>
> Syntax error on line 2 is the following:
> Listen [pppp:qqqq:....:rrrr]:80
>
> ....................
>
> By the way, I thought the following concerning the problem in my CGI PC (my server PC):
>
> Internet-------------Router------Lan-----my PC
>
> When booting PC, apache2 decides that ipv6 is Ok if it gets the ipv6's information and ipv6 is not Ok if it can't get the ipv6's information.
> And apache2 gets the ipv6's information from the router's RA(Router Advertisements).
> But the router can't send RA immediately.
> Therefore when apache2 decides on whether ipv6 is Ok, it can't get the information yet.
> Therefore it decides that ipv6 is not Ok.
> Therefore in case of dual stack, apache2 issues an error because ports.conf is
> as follows:
> Listen a.b.c.d:80
> Listen [pppp:qqqq:....:rrrr]:80
> Listen a.b.c.d:443
> Listen [pppp:qqqq:....:rrrr]:443
> (Because ipv6 address explicitely exists, apache2 issues an error when it can't get ipv6's information.)
> In case of ports.conf being the following:
> Listen 80
> Listen 443,
> apache2 falls back to listen only ipv4 ports because no address format exists.
>
> In fact, in boot sequence, I scroll locked by clicking the Scroll Lock key just before apache2's line appears, and after some moments, I again click the Scroll Lock to restart the boot sequence.
> Then after booting completed, I executed,
> # netstat -an
> And I found there exists Listen 80 and Listen 443 in the tcp6 lines.
>
> My thought is wrong ?
>
> By the way, on the PC of Squeeze desktop install (my second PC),
> After booting completed, on command of
> # netstat -an ,
> I can always find Listen 80 and Listen 443 in the tcp6 lines.
> (Without # /etc/init.d/apache2 restart)
> Why in the desktop environment, "# /etc/init.d/apache2 restart" is not needed ?
> Is apache2 of the desktop environment executed in the other way than CGI environment ?
> In fact, I found,
> /etc/hosts of my GUI PC includes
> # The following lines are desirable for IPv6 capable hosts
> ::1 localhost ip6-localhost ip6-loopback
> fe00::0 ip6-localnet
> ff00::0 ip6-mcastprefix
> ff02::1 ip6-allnodes
> ff02::2 ip6-allrouters
> ff02::3 ip6-allhosts
>
> whereas, /etc/hosts of my CUI PC only includes
> # The following lines are desirable for IPv6 capable hosts
> ::1 ip6-localhost ip6-loopback
> fe00::0 ip6-localnet
> ff00::0 ip6-mcastprefix
> ff02::1 ip6-allnodes
> ff02::2 ip6-allrouters
>
>
> Thanks,
> Satoru
>
>


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Old 10-06-2012, 11:30 AM
Tom H
 
Default dynamic IP assignment on servers = brain damage

On Fri, Oct 5, 2012 at 11:56 PM, Stan Hoeppner <stan@hardwarefreak.com> wrote:
>
> This thread reinforces what experienced server admins round the world
> have known forever:
>
> DO NOT USE dynamic network address assignment on servers.
>
> The problem in this thread is but one of many that can/will result from
> using dynamic IP assignment with servers. If the OP had mentioned his
> use of dynamic IP up front he would have saved himself, and the rest of
> us, much time.

I've had to deal with VPS instances using what I call (in between my
ears!) semi-static ip settings: static but dynamically-assigned ip
addresses. The box gets an ip address via dhcp but it's always the
same, (I assume) based on the NIC's MAC address.


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Old 10-06-2012, 12:43 PM
Miles Fidelman
 
Default dynamic IP assignment on servers = brain damage

Tom H wrote:

On Fri, Oct 5, 2012 at 11:56 PM, Stan Hoeppner <stan@hardwarefreak.com> wrote:

This thread reinforces what experienced server admins round the world
have known forever:

DO NOT USE dynamic network address assignment on servers.

The problem in this thread is but one of many that can/will result from
using dynamic IP assignment with servers. If the OP had mentioned his
use of dynamic IP up front he would have saved himself, and the rest of
us, much time.

I've had to deal with VPS instances using what I call (in between my
ears!) semi-static ip settings: static but dynamically-assigned ip
addresses. The box gets an ip address via dhcp but it's always the
same, (I assume) based on the NIC's MAC address.



Which also comes up if one is net booting - the server has to pick up
its IP address from the boot server, based on its MAC address.




--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra


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Old 10-06-2012, 06:52 PM
Satoru Otsubo
 
Default dynamic IP assignment on servers = brain damage

Hi,
Stan

>
> The problem in this thread is but one of many that can/will result from
> using dynamic IP assignment with servers. If the OP had mentioned his
> use of dynamic IP up front he would have saved himself, and the rest of
> us, much time.
>

Pardon me.
I did not understand that dynamic IP assignment was an important factor to solve the problem.
I apologize that you and the others took much time to consider the cause of the problem.
And pardon me for my poor English.

Satoru


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Old 10-07-2012, 12:43 PM
Stan Hoeppner
 
Default dynamic IP assignment on servers = brain damage

On 10/6/2012 7:43 AM, Miles Fidelman wrote:
> Tom H wrote:
>> On Fri, Oct 5, 2012 at 11:56 PM, Stan Hoeppner
>> <stan@hardwarefreak.com> wrote:
>>> This thread reinforces what experienced server admins round the world
>>> have known forever:
>>>
>>> DO NOT USE dynamic network address assignment on servers.
>>>
>>> The problem in this thread is but one of many that can/will result from
>>> using dynamic IP assignment with servers. If the OP had mentioned his
>>> use of dynamic IP up front he would have saved himself, and the rest of
>>> us, much time.
>> I've had to deal with VPS instances using what I call (in between my
>> ears!) semi-static ip settings: static but dynamically-assigned ip
>> addresses. The box gets an ip address via dhcp but it's always the
>> same, (I assume) based on the NIC's MAC address.
>>
>
> Which also comes up if one is net booting - the server has to pick up
> its IP address from the boot server, based on its MAC address.

But this is only a temporary address during PXE boot. You'd still
want/have a static IP in the OS image which goes live once the kernel is
initialized.

--
Stan


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Old 10-07-2012, 12:49 PM
Stan Hoeppner
 
Default dynamic IP assignment on servers = brain damage

On 10/6/2012 1:52 PM, Satoru Otsubo wrote:
> Hi,
> Stan
>
>>
>> The problem in this thread is but one of many that can/will result from
>> using dynamic IP assignment with servers. If the OP had mentioned his
>> use of dynamic IP up front he would have saved himself, and the rest of
>> us, much time.
>>
>
> Pardon me.
> I did not understand that dynamic IP assignment was an important factor to solve the problem.
> I apologize that you and the others took much time to consider the cause of the problem.
> And pardon me for my poor English.

No need to apologize Satoru. I was simply surprised that you were using
dynamic IP.

Your router isn't responding in a timely fashion when the server
requests an IP address. Thus the server has no IPv6 address in the
stack when Apache loads, which causes your problem. It loads later,
manually, because the router has responded, very late, with an address
assignment, but after Apache2 needs it.

The proper fix is to use a static IP address.

--
Stan


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