Discussion:
OS X oddness?
(too old to reply)
Alex Martin
2016-07-14 00:51:29 UTC
Permalink
Running OS X, and when I connect to a local server via localhost, the
'client address' is always 0.0.0.0. I'm wondering if this is normal, OS
X weirdness, or a bug?
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alm

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Alex Martin
2016-07-14 00:59:10 UTC
Permalink
Post by Alex Martin
Running OS X, and when I connect to a local server via localhost, the
'client address' is always 0.0.0.0. I'm wondering if this is normal, OS
X weirdness, or a bug?
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I'm not too experienced in IP, so I'm not certain if 'client address'
is the right term. 'sender address'? 'return address'? 'source address'?
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alm

Weblog: alexloganmartin.wordpress.com
Moe Trin
2016-07-14 03:54:06 UTC
Permalink
On Wed, 13 Jul 2016, in the Usenet newsgroup comp.protocols.tcp-ip, in article
Post by Alex Martin
Running OS X, and when I connect to a local server via localhost, the
'client address' is always 0.0.0.0.
Lack of info - where do you see the information? Is this something in
the server logs, something displayed by the client, the server, or...
Post by Alex Martin
I'm wondering if this is normal, OS X weirdness, or a bug?
Not enough info. 0.0.0.0 (and in fact the entire 0.x.x.x range) is
IP's version of saying "me, but I don't know my name or address".
From RFC6890 (Special-Purpose IP Address Registries):

+----------------------+----------------------------+
| Attribute | Value |
+----------------------+----------------------------+
| Address Block | 0.0.0.0/8 |
| Name | "This host on this network"|
| RFC | [RFC1122], Section 3.2.1.3 |
| Allocation Date | September 1981 |
| Termination Date | N/A |
| Source | True |
| Destination | False |
| Forwardable | False |
| Global | False |
| Reserved-by-Protocol | True |
+----------------------+----------------------------+

and that's referring to RFC1122 (Requirements for Internet Hosts -
Communication Layers.). OS X - you'd have better luck asking in an
OSX newsgroup (one of the comp.sys.mac.* most likely), but what's in
the /etc/hosts file? On many UNIX like systems, you'd see something
like

[herschel ~]$ cat /etc/hosts
127.0.0.1 localhost
192.168.1.6 herschel.phx.az.us
::1 localhost ip6-localhost ip6-loopback
[herschel ~]$

where this host is known on the LOCAL network as herschel. Is that
first "localhost" line there?

Old guy
Alex Martin
2016-07-14 12:57:21 UTC
Permalink
Post by Moe Trin
On Wed, 13 Jul 2016, in the Usenet newsgroup comp.protocols.tcp-ip, in article
Post by Alex Martin
Running OS X, and when I connect to a local server via localhost, the
'client address' is always 0.0.0.0.
Lack of info - where do you see the information? Is this something in
the server logs, something displayed by the client, the server, or...
This is coming from the server logs (on the same machine), yes.
Post by Moe Trin
Post by Alex Martin
I'm wondering if this is normal, OS X weirdness, or a bug?
Not enough info. 0.0.0.0 (and in fact the entire 0.x.x.x range) is
IP's version of saying "me, but I don't know my name or address".
Thank you. That pretty much answers my question.
Post by Moe Trin
+----------------------+----------------------------+
| Attribute | Value |
+----------------------+----------------------------+
| Address Block | 0.0.0.0/8 |
| Name | "This host on this network"|
| RFC | [RFC1122], Section 3.2.1.3 |
| Allocation Date | September 1981 |
| Termination Date | N/A |
| Source | True |
| Destination | False |
| Forwardable | False |
| Global | False |
| Reserved-by-Protocol | True |
+----------------------+----------------------------+
and that's referring to RFC1122 (Requirements for Internet Hosts -
Communication Layers.). OS X - you'd have better luck asking in an
OSX newsgroup (one of the comp.sys.mac.* most likely), but what's in
the /etc/hosts file? On many UNIX like systems, you'd see something
like
[herschel ~]$ cat /etc/hosts
127.0.0.1 localhost
192.168.1.6 herschel.phx.az.us
::1 localhost ip6-localhost ip6-loopback
[herschel ~]$
where this host is known on the LOCAL network as herschel. Is that
first "localhost" line there?
Yes; it's always there on OS X, and I've just checked.
Post by Moe Trin
Old guy
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--
alm

Weblog: alexloganmartin.wordpress.com
h***@gmail.com
2016-09-28 01:57:38 UTC
Permalink
Post by Alex Martin
Running OS X, and when I connect to a local server via localhost, the
'client address' is always 0.0.0.0. I'm wondering if this is normal, OS
X weirdness, or a bug?
When you setup for the connection, you normally put in 0.0.0.0 for the source address and source port, and let the system fill them in. You would not normally see it with, for example, tcpdump, though.

For a multi-home host, it is usual to fill in the source address based on the interface that it is going out on.
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