Error: Name service error for localhost: Host found but no data

[Tony Earnshaw]

ping localhost is doing fine, dig localhost give me
; <<>> DiG 9.2.1 <<>> localhost
;; global options: printcmd
34921
1, ADDITIONAL: 0
;localhost. IN A
localhost. 600 IN A
127.0.0.1
localhost. 600 IN NS
localhost.
;; Query time: 3 msec
;; SERVER: 192.168.10.1#53(192.168.10.1)
;; WHEN: Mon Nov 3 22:21:42 2003
;; MSG SIZE rcvd: 57
I don't understand why it can find localhost. Isn't
it obvious that even if the machine is not connected,
localhost is resolved to 127.0.0.1 anyways?

Try: 'dig -x 127.0.0.1' and report the result here.
What does /etc/hosts look like?

--Tonni

[Wietse Venema]

My postfix is working fine, and the problem happens
when I tried to set up to set up clamav, spamassassin
and amavisd-new with postfix to scan virus and spam.
Spamassassin, clamav and amavisd-new seems to be
installed and started fine, but postfix is complaining
with the error
Name service error for localhost: Host found but no
data
record of requested type

add localhost to the mydestination setting, for example:

mydestination = $myhostname, localhost.$mydomain localhost

Wietse

[Tony Earnshaw]

Name service error for localhost: Host found but no
data record of requested type

Beg your pardon - this comes from an IPv6 lookup on localhost.

Why Postfix can't find localhost i don't know.

--Tonni

[Wietse Venema]

Post by Tony Earnshaw

Name service error for localhost: Host found but no
data record of requested type

Beg your pardon - this comes from an IPv6 lookup on localhost.
Why Postfix can't find localhost i don't know.

The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in mydestination.

Wietse

[Tony Earnshaw]

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in mydestination.

So "localhost = IP 127.0.0.1" is coded into Postfix?

--Tonni

[V***@morganstanley.com]

Post by Tony Earnshaw

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in mydestination.

So "localhost = IP 127.0.0.1" is coded into Postfix?

No, "localhost" should be listed as a local destination in mydestination.

[Wietse Venema]

Post by Tony Earnshaw

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in mydestination.

So "localhost = IP 127.0.0.1" is coded into Postfix?

I beg your pardon?

Some Postfix distributions have append_dot_mydomain turned off.

Consequently, mail for ***@localhost will be mis-delivered unless
localhost is listed in main.cf's mydestination parameter.

Wietse

[Tony Earnshaw]

Post by V***@morganstanley.com

Post by Tony Earnshaw

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in mydestination.

So "localhost = IP 127.0.0.1" is coded into Postfix?

No, "localhost" should be listed as a local destination in mydestination.

In answer to what Wietse answered originally, I sent a reply asking how
Postfix knew what the IP of localhost was without using DNS or
/etc/hosts. Then I found that I had asked a silly question and assumed
that it consulted its own code, so I 'postsuper -d'ed it.

So how does Postfix know what the IP of localhost is?

--Tonni

[V***@morganstanley.com]

Post by Tony Earnshaw

Post by V***@morganstanley.com
No, "localhost" should be listed as a local destination in mydestination.

So how does Postfix know what the IP of localhost is?

To delivery mail to ***@localhost, Postfix does not need to know the IP
address of localhost. Just list "localhost" in mydestination. If it needs
the IP, the machine is misconfigured and the mail will bounce.

[Wietse Venema]

Post by Tony Earnshaw

Post by V***@morganstanley.com

Post by Tony Earnshaw

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in mydestination.

So "localhost = IP 127.0.0.1" is coded into Postfix?

No, "localhost" should be listed as a local destination in mydestination.

In answer to what Wietse answered originally, I sent a reply asking how
Postfix knew what the IP of localhost was without using DNS or
/etc/hosts. Then I found that I had asked a silly question and assumed
that it consulted its own code, so I 'postsuper -d'ed it.
So how does Postfix know what the IP of localhost is?

It doesn't. Please pay attention to the Subject: line of this thread.

Q: Why does mail for ***@localhost fail with "host not found"?

A: This is a configuration error. List localhost in the main.cf
mydestination parameter, for example:

/etc/postfix/main.cf:
mydestination = $myhostname, localhost.$mydomain localhost

Postfix should never have to look up the IP address of localhost
in order to deliver mail, because localhost should be listed as
a local destination.

Wietse

[Pollywog]

On Mon, 3 Nov 2003 11:07:07 -0500 (EST)

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in
mydestination.

Does this mean that localhost does not need to be listed in
"transports" ?


--
Andrew

[Tony Earnshaw]

Post by Wietse Venema
I beg your pardon?
Some Postfix distributions have append_dot_mydomain turned off.
localhost is listed in main.cf's mydestination parameter.

Wouldn't surprise me if I were proved to be more than usually dense.

If:

1: Postfix doesn't consult DNS or /etc/localhost;
2: No idea of what localhost is, is coded into Postfix:

How does Postfix know what IP localhost has?

--Tonni

[Wietse Venema]

Post by Pollywog
On Mon, 3 Nov 2003 11:07:07 -0500 (EST)

Post by Wietse Venema
The SMTP client should never have to look up localhost. Instead,
localhost should be listed as a local destination in
mydestination.

Does this mean that localhost does not need to be listed in
"transports" ?

Most Postfix systems don't need a transport map at all.

Wietse

[Tony Earnshaw]

Post by Wietse Venema

Post by Tony Earnshaw
In answer to what Wietse answered originally, I sent a reply asking how
Postfix knew what the IP of localhost was without using DNS or
/etc/hosts. Then I found that I had asked a silly question and assumed
that it consulted its own code, so I 'postsuper -d'ed it.
So how does Postfix know what the IP of localhost is?

It doesn't. Please pay attention to the Subject: line of this thread.

I did.

Post by Wietse Venema
A: This is a configuration error. List localhost in the main.cf
mydestination = $myhostname, localhost.$mydomain localhost
Postfix should never have to look up the IP address of localhost
in order to deliver mail, because localhost should be listed as
a local destination.

Ah. localhost is a local destination. Local destinations don't need
looking up. Nothing about localhost in 'man 8 local'.

Thanks!

--Tonni

[Chen Shaopeng]

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localhost, and localhost.$mydomain is already part
of mydestination.
Funny thing, I looked at the debug message, and
postfix
timed out trying to connect to 127.0.0.1.

This does not look like a postfix issue.

Try telnet localhost <port> to see if you can
actually connect, and do netstat -na --ip to see
some program is listening on that specific port.
If you can't telnet, postfix would time out.

Oh, if you have a firewall on that box, verify
your rules too. I fell into this one before,
knowing that my box only offered a number
of services, so I just let those ports
open, and close everything else. Took a while
to figure out that iptables also block the ports
to loopback interface too.

csp

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[Tony Earnshaw]

Post by Tony Earnshaw
Try: 'dig -x 127.0.0.1' and report the result here.
What does /etc/hosts look like?

Ok, looks like my DNS (or hosts setup) is not correct.

This is what my localhost reverse zone looks like:

$TTL 86400
@ IN SOA localhost. root.localhost. (
1997022700 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
IN NS localhost.

1 IN PTR localhost.


600 seconds for TTL (even 86400 seconds) is ridiculously short, since
the PTR record will never change.

Relevant zone in [/var/named|/etc]/named.conf:

zone "0.0.127.in-addr.arpa" IN {
type master;
file "named.local";
allow-update { none; };
};

However, this shouldn't be necessary for Postfix's idea of localhost to
function, as has been pointed out. It *will* be necessary if you do what
you are trying with telnet or whatever, that might need a reverse lookup
(though it won't for 'telnet localhost xx'.

127.0.0.1 mail.mydomain.com localhost.localdomain
localhost

Try swapping:

127.0.0.1 localhost mail.mydomain.com

Do NOT use "localhost.localdomain" - should not exist.

--Tonni