Socket - gaierror

[Douglas Wells]

In article <1188260349.031088.69010 at l22g2000prc.googlegroups.com>,
 half.italian at gmail.com writes:
> On Aug 27, 4:22 pm, s... at signature.invalid (Douglas Wells) wrote:
> > In article <1188244050.029920.314... at i13g2000prf.googlegroups.com>,
> >
> >  half.ital... at gmail.com writes:
> > > On Aug 27, 12:32 pm, Larry Bates <larry.ba... at websafe.com> wrote:
> >
> > > Changing it to IP gives me the same exact error...
> >
> > >   File "bin/prgram.py", line 123, in notify
> > >     smtp = smtplib.SMTP("XXX.XXX.XXX.XXX")
> >
> > >   File "/usr/lib/python2.4/smtplib.py", line 255, in __init__
> > >     addr = socket.gethostbyname(socket.gethostname())
> >
> > > gaierror: (-2, 'Name or service not known')
> >
> > > ~Sean
> >
> > Note that the lookup is of your *local* system name
> > (socket.gethostname()).  I suspect that the name of your client
> > system (the one running the python script) is not registered in
> > DNS.
> >
> > Try ping'ing your own system and see if that resolves in DNS.  In
> > UNIX/Linux you can use the hostname command; in any system you can
> > write a python script to print the result of socket.gethostname().
> >
> >  - dmw
> 
> I found a solution...but still not sure why that happened.
> 
> root at 00:17:08:5E:EF:0F:/usr/local/sw/program/bin# hostname
> 00:17:08:5E:EF:0F
> root at 00:17:08:5E:EF:0F:/usr/local/sw/program/bin# ping 00:17:08:5E:EF:0F
> ping: unknown host 00:17:08:5E:EF:0F
> 
> >>> socket.gethostname()
> '00:17:08:5E:EF:0F'
> 
> Workaround: pass the 'local_hostname' arg to the smtplib.SMTP() call
> with "localhost"
> 
> ie smtp.SMTP("some.computer", local_hostname="localhost")
> 
> This is just overriding the socket.gethostname() call entirely.
> 
> Did a bit of testing with the /etc/hosts file, and even with an entry
> to the hostname it can't resolve the ip.
> The problem is the name "00:17:08:5E:EF:0F"  PS.  I didn't choose to
> set the hostname that way.
> 
> ~Sean

That would be a reasonable workaround.  The process of sending
e-mail via SMTP could need the local host name for at least two
uses:  1) the SMTP initial connection (RFC 2821) requires the
client to identify itself (provide its host name); 2) the mail
headers (RFC 2822) should include a return address, which probably
defaults to using your user name at your client host name.

The hostname of your system (00:17:08:5E:EF:0F) is silly when used
with SMTP.  Your system administrator is either ill-informed or is
actively trying to prevent users from using their systems as
servers. It has the form of an IPv6 numeric host address.

Given the pathnames in your command interchange, you have a UNIX,
Linux, or UNIX-like system. According to the Linux and UNIX standards:

  - If your system is IPv6-capable, the use of such a name with
    gethostbyname invokes "unspecified behavior."   First, the function
    is not defined to work with such "numeric" identifiers.  Second,
    it is not guaranteed to work with non-IPv4 names, and probably
    can't be registered in pre-i18n DNS data bases.

  - Even if your system is not IPv6-capable, such a host name is going
    to confuse many other systems that would be IPv6-capable and attempt
    to resolve the odd-ball name that your system provides.

  - Even if that worked, you're providing an IPv6 name form in
    conjunction with an IPv4 protocol (at least when you explicitly
    provide the IP address as a dotted-quad).

 - dmw

-- 
.   Douglas Wells             .  Connection Technologies      .
.   Internet:  -sp9804- -at - contek.com-                     .