detecting if I am connected to a ISP

[Brett S Hallett]

Hi, I have written a small mail pre-viewer in Ruby/FXRuby which allows a
graphic view of incoming mail headers, from
which I can select canditates for deletion before loading,
I an using POP, however I cannot see any way to detect that the user
has actually connected to their ISP before running
the program, natually I recieve a 'system error.

 

[Lothar Scholz]

Generally, if they aren't connected to the network, they'll get a
network unreachable error. So you could try something along the lines
of this (very untested) code:

begin
TCPSocket.new(mailserver, "pop-3")
rescue e => Errno::ENETUNREACH
puts "Are you connected?"
end

It's better to check for a high performance/high available site like
"www.google.com". If you can't reach them it's a network problem.
But this can popup a please connect window on Windows, which is not
desireable in periodic mail checks etc.

 

[Farrel Lifson]

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I wrote a Ruby script that connected to my ISP a while ago. To test if I
was connected I would run ifconfig and then parse the first line
returned and look for 'ppp' (the name of the connection). This is a bit
hackish and I'm pretty sure there is a better way to do it.

Farrel
--=20
Data Network Architecture Research Lab mailto:[email protected]
Dept. of Computer Science http://people.cs.uct.ac.za/~flifs=
on
University of Cape Town +27-21-650-3127

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[JoeSeeder]

[..] I would run ifconfig and then parse [..]

you don't have to call external apps, you can parse /proc/net/dev

 

[Jason Williams]

[..] I would run ifconfig and then parse [..]

you don't have to call external apps, you can parse /proc/net/dev

The obvious problem with both of these solutions, of course, is that
you've shot any kind of portability through both kneecaps.

 

[daz]

[..] I would run ifconfig and then parse [..]

you don't have to call external apps, you can parse /proc/net/dev

The obvious problem with both of these solutions, of course, is that
you've shot any kind of portability through both kneecaps.

Made me chuckle, anyway <gg>.
---

## OMG!, What's this ?
## Non-production crufty hack-type example.

require 'socket'

ip = IPSocket.getaddress(Socket.gethostname)
print 'My guess is that you '
if ip == '127.0.0.1'
print 'are NOT'
else
print 'ARE'
end
puts ' connected at this time'


There may be an issue where a site has multiple IP addresses.
I've never seen what is returned in these situations --
(Array, comma separated String) ?
but if someone could post an example, there may be a general
solution someone could provide.

At least, it doesn't trigger the 'Do you want to connect?'
on Windows.


daz

 

[Dennis Oelkers]

In my opinion the only portable and secure way is just to connect to
the mailserver using socket calls while catching any exceptions.
The result of any other solution will not be predictable, and is in
no way sufficient to draw a conclusion about the state of a net
connection and even provokes race conditions.

If the problem is that this could make some "Do you want to dial-in?"
window pop up on some less-clued operating systems you could increase
your timer interval to a reasonable high number to prevent that from
happening too often.

Just my $0,02,
Dennis Oelkers
--
Dennis Oelkers | Webadministration | Zentraleinrichtung Rechenzentrum
TU-Berlin | EN-Gebaeude, K042 | Telefon: 030-314-25029

Key Fingerprint:
A6 7A B6 90 09 56 E8 32 02 40 6B 27 80 17 00 89 61 E7 CA 6F

 

[Rob Partington]

It's better to check for a high performance/high available site like
"www.google.com". If you can't reach them it's a network problem.

How is that better than trying to connect to the mail server and port
they're about to download mail from? If you can't get to it, it matters
not one jot whether you can get to google, you still can't get the mail.

(I can think of several reasons why someone might not be able to reach
google, but would be able to reach their mail server.)