Testing for Internet Connection

[Alexnb]

Hello internet.

I am wondering, is there a simple way to test for Internet connection? If
not, what is the hard way :p
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[Alex Marandon]

Re: Testing for Internet Connection

Alexnb wrote:

I am wondering, is there a simple way to test for Internet connection? If
not, what is the hard way :p

Trying to fetch the homepage from a few major websites (Yahoo, Google,
etc.)? If all of them are failing, it's very likely that the connection
is down. You can use urllib2 [1] to accomplish that.

[1] <http://docs.python.org/lib/module-urllib2.html>

[Ben Finney]

Re: Testing for Internet Connection

Alexnb <alexnbryan@gma il.comwrites:

I am wondering, is there a simple way to test for Internet
connection? If not, what is the hard way :p

Refine the question: What do you mean by "internet"? It isn't a single
entity.

Do you mean "some particular internet host responding on a particular
network port"?

If you can define exactly what you mean by "internet connection", the
test for it becomes correspondingly easier.

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`\ for me?” —Groucho Marx |
_o__) |
Ben Finney

[Thomas Troeger]

Re: Testing for Internet Connection

Alex Marandon wrote:

Alexnb wrote:

>I am wondering, is there a simple way to test for Internet connection? If
>not, what is the hard way :p

>
Trying to fetch the homepage from a few major websites (Yahoo, Google,
etc.)? If all of them are failing, it's very likely that the connection
is down. You can use urllib2 [1] to accomplish that.
>
[1] <http://docs.python.org/lib/module-urllib2.html>

This seems to work and is rather fast and wastes no bandwidth:

=============== =============== =============== =============== =============== ===
#!/usr/bin/python

import socket, struct

def check_host(host , port, timeout=1):
"""
Check for connectivity to a certain host.
"""
# assume we have no route.
ret=False

# connect to host.
try:
# create socket.
sock=socket.soc ket()
# create timeval structure.
timeval=struct. pack("2I", timeout, 0)
# set socket timeout options.
sock.setsockopt (socket.SOL_SOC KET, socket.SO_RCVTI MEO, timeval)
sock.setsockopt (socket.SOL_SOC KET, socket.SO_SNDTI MEO, timeval)
# connect to host.
sock.connect((h ost, port))
# abort communications.
sock.shutdown(S HUT_RDWR)
# we have connectivity after all.
ret=True
except:
pass

# try to close socket in any case.
try:
sock.close()
except:
pass

return ret

# -------------------------------- main ---------------------------------

if check_host("www .heise.de", 80):
print "Horray!"
else:
print "We've lost headquarters!"
=============== =============== =============== =============== =============== ===

I hope the code is ok, but there is always something you can do better.
Comments? :)

Cheers,
Thomas.

[Marc Christiansen]

Re: Testing for Internet Connection

Alex Marandon <invalid@nowher e.invalid.orgwr ote:

Alexnb wrote:

>I am wondering, is there a simple way to test for Internet connection? If
>not, what is the hard way :p

>
Trying to fetch the homepage from a few major websites (Yahoo, Google,
etc.)? If all of them are failing, it's very likely that the connection
is down

or there is a mandatory proxy...

Does it count as internet connection, when only port 80 and port 443 are
accessible and those require going through a proxy (very strict firewall
policy)? Or everything requires using SOCKS?
Just some possible problems I came up with. I don't know how often some-
thing like this will happen.

Ciao
Marc

[Alexnb]

Re: Testing for Internet Connection




Ben Finney-2 wrote:

Alexnb <alexnbryan@gma il.comwrites:

>I am wondering, is there a simple way to test for Internet
>connection? If not, what is the hard way :p

Refine the question: What do you mean by "internet"? It isn't a single
entity.

Do you mean "some particular internet host responding on a particular
network port"?

If you can define exactly what you mean by "internet connection", the
test for it becomes correspondingly easier.

--
\ “Why should I care about posterity? What's posterity everdone |
`\ for me?” —Groucho Marx |
_o__) |
Ben Finney
--

http://mail.python.org/mailman/listinfo/python-list

Well, really I just need to figure out if I am able to connect to one site.
That site is dictionary.com.
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[Grant Edwards]

Re: Testing for Internet Connection

>If you can define exactly what you mean by "internet connection", the

>test for it becomes correspondingly easier.

Well, really I just need to figure out if I am able to connect
to one site. That site is dictionary.com.

Then use urllib2 to try to fetch a page from dictionary.com. If
it works, you're "connected" . If it fails, you're not. The
most straight-forward way to find out if you can do X is to try
to do X.

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at gobble it!!
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[Alexnb]

Re: Testing for Internet Connection




Troeger Thomas (Ext) wrote:

>
Alex Marandon wrote:

>Alexnb wrote:

>>I am wondering, is there a simple way to test for Internet connection?
>>If
>>not, what is the hard way :p

>>
>Trying to fetch the homepage from a few major websites (Yahoo, Google,
>etc.)? If all of them are failing, it's very likely that the connection
>is down. You can use urllib2 [1] to accomplish that.
>>
>[1] <http://docs.python.org/lib/module-urllib2.html>

>
This seems to work and is rather fast and wastes no bandwidth:
>
=============== =============== =============== =============== =============== ===
#!/usr/bin/python
>
import socket, struct
>
def check_host(host , port, timeout=1):
"""
Check for connectivity to a certain host.
"""
# assume we have no route.
ret=False
>
# connect to host.
try:
# create socket.
sock=socket.soc ket()
# create timeval structure.
timeval=struct. pack("2I", timeout, 0)
# set socket timeout options.
sock.setsockopt (socket.SOL_SOC KET, socket.SO_RCVTI MEO, timeval)
sock.setsockopt (socket.SOL_SOC KET, socket.SO_SNDTI MEO, timeval)
# connect to host.
sock.connect((h ost, port))
# abort communications.
sock.shutdown(S HUT_RDWR)
# we have connectivity after all.
ret=True
except:
pass
>
# try to close socket in any case.
try:
sock.close()
except:
pass
>
return ret
>
# -------------------------------- main ---------------------------------
>
if check_host("www .heise.de", 80):
print "Horray!"
else:
print "We've lost headquarters!"
=============== =============== =============== =============== =============== ===
>
I hope the code is ok, but there is always something you can do better.
Comments? :)
>
Cheers,
Thomas.
--

http://mail.python.org/mailman/listinfo/python-list

>
>

Thomas this code did not work on google.com and I also tried it with port
443
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[Alexnb]

Re: Testing for Internet Connection




Alex Marandon-3 wrote:

>
Alexnb wrote:

>I am wondering, is there a simple way to test for Internet connection? If
>not, what is the hard way :p

>
Trying to fetch the homepage from a few major websites (Yahoo, Google,
etc.)? If all of them are failing, it's very likely that the connection
is down. You can use urllib2 [1] to accomplish that.
>
[1] <http://docs.python.org/lib/module-urllib2.html>
--

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>
>

What exactly do you think will work? I am not sure what you think I should
do? If I use urlopen("http://www.google.com" ) and I am not connected, I am
not going to get an exception, the program will fail.

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[Grant Edwards]

Re: Testing for Internet Connection

On 2008-07-15, Alexnb <alexnbryan@gma il.comwrote:

What exactly do you think will work? I am not sure what you
think I should do? If I use urlopen("http://www.google.com" )
and I am not connected, I am not going to get an exception,
the program will fail.

Bullshit. You get an exception. Here's my program:

import urllib2
try:
con = urllib2.urlopen ("http://www.google.com/")
data = con.read()
print data
except:
print "failed"

If I run it with no internet connection, I get this:

$ python testit.py
failed

If I bring up the internet connection, then I get a bunch of
HTML.

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[norseman]

Re: Testing for Internet Connection


Grant Edwards wrote:

On 2008-07-15, Alexnb <alexnbryan@gma il.comwrote:
>

>What exactly do you think will work? I am not sure what you
>think I should do? If I use urlopen("http://www.google.com" )
>and I am not connected, I am not going to get an exception,
>the program will fail.

>
Bullshit. You get an exception. Here's my program:
>
import urllib2
try:
con = urllib2.urlopen ("http://www.google.com/")
data = con.read()
print data
except:
print "failed"
>
If I run it with no internet connection, I get this:
>
$ python testit.py
failed
>
If I bring up the internet connection, then I get a bunch of
HTML.
>

=============== ==============
Yep -me two

Process:
copy/paste into afile
slide lines left to create proper indent values
save
python afile

I get same as Grant


If one does a copy/paste into interactive Python, it does fail.
(Lots of indent error messages. After all, it is Python :)


Steve
norseman@hughes .net

[Grant Edwards]

Re: Testing for Internet Connection

On 2008-07-15, norseman <norseman@hughe s.netwrote:

Process:
copy/paste into afile
slide lines left to create proper indent values
save
python afile
>
I get same as Grant
>
>
If one does a copy/paste into interactive Python, it does fail.
(Lots of indent error messages. After all, it is Python :)

I'm always a bit conflicted about how to post code snippets.
IMO, the posting is a lot more readable if the code is indented
to offset it from the prose, but it does make more work for
anybody who wants to run the example.

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at
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