Carlos E. R. wrote:
The Thursday 2008-01-17 at 20:32 +0100, Sandy Drobic wrote:
Does IP now send host names along with the IP address? Any such
announcement would have to be application dependent. The name I've
No, unless the developer likes pain, the resolution is the job of the os.
If your box opens a connection to a remote server then the remote
server only sees the ip address of your box. The only way to get a
hostname for that ip address is to look up the ptr record of that ip
from the authoritative dns server responsible for the address space
that contains the ip address of your box.
I think there are exceptions, for example in email. Look, from one of mine:
Received: from nimrodel.valinor (88.*.*.*) by ctsmtpout2.frontal.correo
(7.2.056.6) (authenticated as ***)
id *** for [email protected]; Thu, 17 Jan 2008 16:29:13 +0100
The smtp server of my ISP logs that my machine names itself as
nimrodel.valinor, and then logs the real IP
:-)
This is not what will appear in the log of the server. What you see here in
the received line is not the dns hostname but your HELO name. (^-^)
Postfix for example logs both the hostname AND the HELO name i the received
lines to avoid such misunderstandings. (^-^)
telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 japantest.homelinux.com ESMTP Postfix
ehlo bush.must.go!
250-katgartest.washu.lab
250-PIPELINING
250-SIZE 52428800
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from:<[EMAIL PROTECTED]>
250 2.1.0 Ok
rcpt to:<[EMAIL PROTECTED]>
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
.
250 2.0.0 Ok: queued as 0344414F0C
quit
221 2.0.0 Bye
Connection closed by foreign host.
This is the server log of the mail:
--------------------------------------------------------
Jan 17 22:25:37 katgartest postfix/smtpd[13883]: connect from
localhost[127.0.0.1]
Jan 17 22:26:25 katgartest postfix/smtpd[13883]: 1779514F0C:
client=localhost[127.0.0.1]
Jan 17 22:26:33 katgartest postfix/cleanup[13884]: 1779514F0C:
message-id=<[EMAIL PROTECTED]>
Jan 17 22:26:33 katgartest postfix/qmgr[13530]: 1779514F0C:
from=<[EMAIL PROTECTED]>, size=357, nrcpt=1 (queue active)
Jan 17 22:26:35 katgartest postfix/smtpd[13883]: disconnect from
localhost[127.0.0.1]
--------------------------------------------------------
This is the data part of the mail:
--------------------------------------------------------
Received: from bush.must.go! (localhost [127.0.0.1])
by katgartest.washu.lab (Postfix) with ESMTP id 1779514F0C
for <[EMAIL PROTECTED]>; Thu, 17 Jan 2008 22:26:06 +0100 (CET)
--------------------------------------------------------
Now it's pretty clear that this can't be a dns name. (^-^)
According to RFC 2821 this SHOULD be a dns name...
--
Sandy
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