Using Squid on Intermittent Connections
Subject:   squid
Date:   2001-10-22 08:21:49
From:   rooh
How do you deal with dial-up connections? Where does Squid fit in?
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Showing messages 1 through 3 of 3.

  • Jennifer Vesperman photo squid on dial-up
    2003-01-28 15:18:08  Jennifer Vesperman | O'Reilly Author [View]

    If you have a dial-up connection and an in-house lan, you can put squid (with the patch) between the dial-up and the workstations.

    You can then browse as normal, and if it's connected squid will fetch stale web pages from the net, and if not, it will serve them from the cache.

    Does that explain it better?

    Jenn V.
    • squid on dial-up
      2003-10-20 11:41:31  anonymous2 [View]

      I can see, in general, how the scheme is supposed to work; I'm less sure of the nuts 'n bolts of how you put it together.

      Presumably, you give your browser the hostname and port on which squid listens as its proxy server details.

      How does squid 'know' where to go for its information stream from the 'net? Again, presumably, the default is to use something like ppp to manage the modem link, but how does squid know that its ppp (or whatever) that will be doing the talking to the modem? I didn't see a squid.conf entry that might define this, or am I overlooking something obvious?

      Equally, presumably (but wandering to the very edge of the topic...) if this is happening on a remote machine (I'm assuming that ppp & squid are running on a server) you need to do something like a perl script with sockets to remotely turn ppp on and off as appropriate. Or have I overcomplicated this?

      m a r k underscore w at techie dot com
      (delete spaces, underscore = _, dot = .)
      • Jennifer Vesperman photo squid on dial-up
        2003-10-20 17:54:53  Jennifer Vesperman | O'Reilly Author [View]

        To answer 'how does Squid know where to go', check the paragraph starting:
        "The new directive network_interface takes a string parameter, which is the name of the network interface to check."

        Also, you've missed how the patch works. All a patched Squid cares about is 'can I connect to a remote site or not?'. If so, it runs in connected mode. If not, in disconnected mode.
        A patched Squid does NOT turn the modem on itself, if you want to do that you need to set up dial-on-demand at the OS level, and you DON'T want this patch.

        To quote from the article:

        "The patch must be able to tell whether or not the connection is up.
        If it is connected, it must run as if in standard mode: expiring web pages; replacing stale web pages, if requested; and expiring and removing stale DNS entries.
        If disconnected, it must run almost as if in offline mode -- except it must mark old pages and DNS entries as stale, so they can be removed or replaced when Squid is next connected."

        If a patched Squid can't reach past your gateway, it (probably) won't trigger a dial-on-demand.

        (If this seems nonsensical to you - well, we live in a place where local calls are charged per call. Without having tested it, I assume unpatched Squid will already trigger dial-on-demand if dial-on-demand is set up in the OS; which is useful for people charged per unit time. This patch provides a method of proxying over dialup which is useful for people who are charged per call. Make more sense now?)