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Posted to users@spamassassin.apache.org by Niek <ni...@asbak.coding-slaves.com> on 2005/06/09 13:18:16 UTC
Re: DNS lookups
On 6/9/2005 2:15 PM +0200, Ronan McGlue wrote:
> hi
>
> SA is continually looking up my 3 mailhubs to our local DNS even though
> i have them hardcoded into /etc/hosts and /etc/nsswitch.conf is
> configured properly etc etc...
>
> How can I make SA use the hosts file if such an option exists... anyone
> else notice this behaviour??
>
> ronan
perhaps the file to use is /etc/resolv.conf ?
Niek Baakman
Re: DNS lookups
Posted by jdow <jd...@earthlink.net>.
From: "Jeff Chan" <je...@surbl.org>
> On Thursday, June 9, 2005, 5:32:23 AM, Ronan McGlue wrote:
> > Niek wrote:
> >> On 6/9/2005 2:19 PM +0200, Ronan McGlue wrote:
> >>
> >>> sry should have added that the DNS order in /etc/resolv.conf is also
> >>> correct...
> >>
> >>
> >> What order ? The nameservers are used randomly...
> > again, my semantics need work... :S
>
> > the DNS *is in* order in /etc/resolv.conf...
>
>
> > anyclues as to why SA isnt 'apparently' using the hosts file??
>
> > ronan
>
> Don't use /etc/hosts for anything other than specifying the
> basics of your local machine. /etc/hosts is only used by the
> system during boot time before BIND is up. After that, BIND
> is responsible for name resolution.
There is a nice little trick if you have this line in your /etc/host.conf
file: "order hosts,bind". Add addresses to which you do not want any
information sent to that list. The effect is amusing. It is also quite
handy when one of the SARE sites goes down. You can override the rotary
DNS lookup and actually make rules downloads.
{^_-} <- sneaky old bit**, ain't I?
Re: DNS lookups
Posted by Ronan McGlue <r....@qub.ac.uk>.
Jeff Chan wrote:
> On Thursday, June 9, 2005, 5:32:23 AM, Ronan McGlue wrote:
>
>>Niek wrote:
>>
>>>On 6/9/2005 2:19 PM +0200, Ronan McGlue wrote:
>>>
>>>
>>>>sry should have added that the DNS order in /etc/resolv.conf is also
>>>>correct...
>>>
>>>
>>>What order ? The nameservers are used randomly...
>>
>>again, my semantics need work... :S
>
>
>>the DNS *is in* order in /etc/resolv.conf...
>
>
>
>>anyclues as to why SA isnt 'apparently' using the hosts file??
>
>
>>ronan
>
>
> Don't use /etc/hosts for anything other than specifying the
> basics of your local machine. /etc/hosts is only used by the
> system during boot time before BIND is up. After that, BIND
> is responsible for name resolution.
>
> Jeff C.
yes, but BIND isnt running on the machine in question... (atm)
The nets guys here are seeing a lot of lookups from this SPAMD machine
for our mailhubs to the Local dns...
which is an extra couple of miliseconds i want to avoid by specifying
them in the /etc/hosts file.
I've restarted INETD but the SPAMD machine is still looking up the hubs
to send the results of the messages back...
--
========
Regards
Ronan McGlue
Info. Services
QUB
Re: DNS lookups
Posted by Jeff Chan <je...@surbl.org>.
On Thursday, June 9, 2005, 5:32:23 AM, Ronan McGlue wrote:
> Niek wrote:
>> On 6/9/2005 2:19 PM +0200, Ronan McGlue wrote:
>>
>>> sry should have added that the DNS order in /etc/resolv.conf is also
>>> correct...
>>
>>
>> What order ? The nameservers are used randomly...
> again, my semantics need work... :S
> the DNS *is in* order in /etc/resolv.conf...
> anyclues as to why SA isnt 'apparently' using the hosts file??
> ronan
Don't use /etc/hosts for anything other than specifying the
basics of your local machine. /etc/hosts is only used by the
system during boot time before BIND is up. After that, BIND
is responsible for name resolution.
Jeff C.
--
Jeff Chan
mailto:jeffc@surbl.org
http://www.surbl.org/
Re: DNS lookups
Posted by Jeff Chan <je...@surbl.org>.
On Thursday, June 9, 2005, 11:00:50 PM, Bob Proulx wrote:
> Kenneth Porter wrote:
>> Bob Proulx wrote:
>> > In both cases you would need to modify /etc/resolv.conf to use the
>> > local nameserver instead of the current one.
>>
>> Wiki fodder?
> Good point. Okay, here is the initial page with the above
> information.
> http://wiki.apache.org/spamassassin/CachingNameserver
> Bob
Looks good, but might it be appropriate to add a section about
rbldnsd for high volume mail servers (more than 100,000 messages
per day)? rbldnsd is immensely faster and smaller than BIND and
with rsync of the RBL zone files will prevent all external DNS
lookup, i.e. all hosted RBL lookups become local.
Jeff C.
--
Jeff Chan
mailto:jeffc@surbl.org
http://www.surbl.org/
Re: DNS lookups
Posted by Bob Proulx <bo...@proulx.com>.
Kenneth Porter wrote:
> Bob Proulx wrote:
> > In both cases you would need to modify /etc/resolv.conf to use the
> > local nameserver instead of the current one.
>
> Wiki fodder?
Good point. Okay, here is the initial page with the above
information.
http://wiki.apache.org/spamassassin/CachingNameserver
Bob
Re: DNS lookups
Posted by Kenneth Porter <sh...@sewingwitch.com>.
--On Thursday, June 09, 2005 10:25 AM -0600 Bob Proulx <bo...@proulx.com>
wrote:
> Kenneth Porter wrote:
>> If it's a Red Hat system (including Fedora), just install the
>> caching-nameserver RPM. It pulls in BIND and installs appropriate config
>> files. Then edit resolv.conf to point to localhost.
>
> If it is a Debian system just install bind9 and the default
> configuration is a caching nameserver.
>
> apt-get install bind9
>
> In both cases you would need to modify /etc/resolv.conf to use the
> local nameserver instead of the current one.
Wiki fodder?
Re: DNS lookups
Posted by Bob Proulx <bo...@proulx.com>.
Kenneth Porter wrote:
> If it's a Red Hat system (including Fedora), just install the
> caching-nameserver RPM. It pulls in BIND and installs appropriate config
> files. Then edit resolv.conf to point to localhost.
If it is a Debian system just install bind9 and the default
configuration is a caching nameserver.
apt-get install bind9
In both cases you would need to modify /etc/resolv.conf to use the
local nameserver instead of the current one.
Bob
Re: DNS lookups
Posted by Kenneth Porter <sh...@sewingwitch.com>.
--On Thursday, June 09, 2005 11:03 AM -0400 Steven Dickenson
<st...@mrchuckles.net> wrote:
> We run bind with no zones on our SA gateway to serve as a DNS cache.
> Helps take a load off DNS lookups for common hosts. You can easily do
> this with any other DNS daemon as well. Google for caching nameserver.
If it's a Red Hat system (including Fedora), just install the
caching-nameserver RPM. It pulls in BIND and installs appropriate config
files. Then edit resolv.conf to point to localhost.
Re: DNS lookups
Posted by Steven Dickenson <st...@mrchuckles.net>.
Ronan McGlue wrote:
>> This is because SA doesn't use the system resolver, it uses Net::DNS's
>> resolver. This gives SA a lot of control over queries, but doesn't
>> take advantage of things like /etc/hosts, and only uses your primary DNS.
>
> ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh ok
> anyway i can hack it??
> *goes off to read CPAN*...
We run bind with no zones on our SA gateway to serve as a DNS cache.
Helps take a load off DNS lookups for common hosts. You can easily do
this with any other DNS daemon as well. Google for caching nameserver.
- S
Re: DNS lookups
Posted by jdow <jd...@earthlink.net>.
From: "Ronan McGlue" <r....@qub.ac.uk>
> Matt Kettler wrote:
> > At 08:32 AM 6/9/2005, Ronan McGlue wrote:
> >
> >> anyclues as to why SA isnt 'apparently' using the hosts file??
> >
> >
> > This is because SA doesn't use the system resolver, it uses Net::DNS's
> > resolver. This gives SA a lot of control over queries, but doesn't take
> > advantage of things like /etc/hosts, and only uses your primary DNS.
>
> ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh ok
> anyway i can hack it??
> *goes off to read CPAN*...
tinydns. That's a caching only name server. It can reduce the number
of lookups for your primary DNS, perhaps.
{^_^}
Re: DNS lookups
Posted by Ronan McGlue <r....@qub.ac.uk>.
Matt Kettler wrote:
> At 08:32 AM 6/9/2005, Ronan McGlue wrote:
>
>> anyclues as to why SA isnt 'apparently' using the hosts file??
>
>
> This is because SA doesn't use the system resolver, it uses Net::DNS's
> resolver. This gives SA a lot of control over queries, but doesn't take
> advantage of things like /etc/hosts, and only uses your primary DNS.
ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh ok
anyway i can hack it??
*goes off to read CPAN*...
--
========
Regards
Ronan McGlue
Info. Services
QUB
Re: DNS lookups
Posted by Matt Kettler <mk...@comcast.net>.
At 08:32 AM 6/9/2005, Ronan McGlue wrote:
>anyclues as to why SA isnt 'apparently' using the hosts file??
This is because SA doesn't use the system resolver, it uses Net::DNS's
resolver. This gives SA a lot of control over queries, but doesn't take
advantage of things like /etc/hosts, and only uses your primary DNS.
Re: DNS lookups
Posted by Ronan McGlue <r....@qub.ac.uk>.
Niek wrote:
> On 6/9/2005 2:19 PM +0200, Ronan McGlue wrote:
>
>> sry should have added that the DNS order in /etc/resolv.conf is also
>> correct...
>
>
> What order ? The nameservers are used randomly...
again, my semantics need work... :S
the DNS *is in* order in /etc/resolv.conf...
anyclues as to why SA isnt 'apparently' using the hosts file??
ronan
>
> Niek Baakman
--
========
Regards
Ronan McGlue
Info. Services
QUB
Re: DNS lookups
Posted by Niek <ni...@asbak.coding-slaves.com>.
On 6/9/2005 2:19 PM +0200, Ronan McGlue wrote:
> sry should have added that the DNS order in /etc/resolv.conf is also
> correct...
What order ? The nameservers are used randomly...
Niek Baakman
Re: DNS lookups
Posted by Ronan McGlue <r....@qub.ac.uk>.
Niek wrote:
> On 6/9/2005 2:15 PM +0200, Ronan McGlue wrote:
>
>> hi
>>
>> SA is continually looking up my 3 mailhubs to our local DNS even
>> though i have them hardcoded into /etc/hosts and /etc/nsswitch.conf is
>> configured properly etc etc...
>>
>> How can I make SA use the hosts file if such an option exists...
>> anyone else notice this behaviour??
>>
>> ronan
>
>
> perhaps the file to use is /etc/resolv.conf ?
sry should have added that the DNS order in /etc/resolv.conf is also
correct...
>
> Niek Baakman
>
--
========
Regards
Ronan McGlue
Info. Services
QUB