On 13 Feb 2007, in the Usenet newsgroup comp.os.linux.networking, in article
<(E-Mail Removed) .com>, Josh Converse wrote:
>This data is stored temporarily in a relational database, to be
>offloaded to a server later. I'm trying to transfer that data to a
>server located at a university campus over a 56k Modem. The problem
>lies in the fact that there is no internet access available at this
>location (i.e. the ISP fees are not available in the budget of this
>project), and the phone call to the university is long-distance. This
>means that the connection will have to be (automatically) initiated
>from the server on campus (Also Slackware 11) to the remote site.
OK. Key point is that there is a modem that can "answer the phone"
at this remote site. That's all that is needed.
>The point of this question is this:
>What would be an appropriate protocol/application/etc for
>accomplishing this? In my searches, I've come across a few different
>options:
>
>* Initiating the connection and using ppp (I assume from there things
>behave more like a tcp/ip connection)
>* Snagging a terminal using something like mgetty
>* UUCP
ppp connection - the remote becomes a mini ISP, and you dialin from
the university. The university end is merely a cron-job to initiate a
connection, download a file when connected, and hang up. See the
PPP-HOWTO and Bill Unruh's web page at
http://www.theory.physics.ubc.ca/ppp-linux.html or
http://axion.physics.ubc.ca/ppp-linux.html I'd set a cron entry
like "03 05 * * * /usr/local/bin/call.remote.site" (assumes Dillon
cron normally found in Slackware), where 'call.remote.site' is a dumb
script something like
#!/bin/bash
exec /usr/sbin/pppd connect "/usr/sbin/chat -f /etc/ppp/dialscript" lock \
defaultroute noipdefault nodetach /dev/modem 115200 crtscts idle 20 \
user datagrabber
and /etc/ppp/dialscript contains a simple string to make the connection,
such as
ABORT BUSY ABORT 'NO CARRIER' "" AT&F0 OK ATDT2662902 CONNECT \d\c
The file /etc/ppp/pap-secrets would contain "datagrabber * p42Sw0rD"
as appropriate. /see the ppp and chat man pages for the meaning of the
various options. The file '/etc/ppp/ip-up' can be used to kick off
an FTP data retrieval. The 'idle 20' in the script causes pppd to
disconnect after 20 seconds of inactivity on the link. The 'AT&F0'
is suitable for nearly all modems - US Robotics want 'AT&F1'. See the
manual for your modem.
On the remote system, you run a "ppp server" as detailed in the web
page and HOWTO. I'd recommend using PAP (or CHAP) authentication rather
than an old fashioned UNIX style "Login:" prompt. If you use CHAP, the
file on the box dialing in changes from 'pap-secrets' to 'chap-secrets'
and no other change is needed.
As far as using UUCP - that's also a possibility, though it's rarely
used any more. There is a UUCP-HOWTO, and an entire chapter in the
Linux Network Administrator's guide available at any LDP mirror if it's
not on your system as well. Try
http://tldp.org/guides.html
>I'm fine with writing scripts to take care of the automation portion of
>things - it's just the communications aspect is a hurdle. I've spent a
>lot of time googling the web and the newsgroups, but I feel like my
>search queries aren't as effective as they could be because of my lack
>of knowledge/intuition on the matter.
I'd suggest the pppd solution, as it's a pretty solid protocol that's
been around for years (as has UUCP - but pppd is in wide use current;y).
You grabbing data, and doing any housekeeping then becomes a simple
networking task. Using a non-obvious username (and good password) will
protect you against any phone phreaks that may still exist and happen
upon the telephone number.
Old guy
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