Disable SSH using Cron

Discussion in 'Tomato Firmware' started by ImGeo, Mar 31, 2010.

  1. ImGeo

    ImGeo Addicted to LI Member

    Is there some command to disable(/enable) SSH (dropbear) over cron?
    I've looked at the section on SSH and have a general idea of cron (from looking at FAQ), but didn't find any commands or a way to start/stop SSH.

    I know it can be done via GUI, but I want to run a script to disable SSH every 4AM (for times when I forget to disable it after I'm done using it).
  2. ImGeo

    ImGeo Addicted to LI Member

    Well, the progress I made so far is to figure out how to start it (basically, just run "dropbear", or more specifically (derived from "ps") "dropbear -p 22 -a").

    but I still havn't figured out how to stop it. "ps | grep dropbear" does return something useful like:
    1084 root 940 S dropbear -p 22 -a
    1135 root 1456 S grep dropbear
    and I can run "kill 1084", except that I need to somehow pass 1084 (which can really be any number) to kill...

    any help?


    from reading dropbear's info, I found out that it saves the PID to:
    /var/run/dropbear.pid , and inside that is the PID, just plain "1084"
    so .... how do I use that?
  3. mstombs

    mstombs Network Guru Member

    You can use pidof(), but "killall dropbear" should kill all.
  4. rhester72

    rhester72 Network Guru Member

    I haven't tested it, but something along the lines of "service ssh stop" or "service sshd stop" _may_ also work.

  5. ImGeo

    ImGeo Addicted to LI Member

    Thanks! This works. @rhester72, I tried both, but it ddin't work.

    Now... my cron doesn't work properly:
    # cru l
    00 4 * * * killall dropbear #KillDropBear#

    that should run every 4:00AM, right? well it's not 4am, so I wrote a cron that's 1 minute ahead of the current time (shown in the router overview page), and it never killed dropbear (ps | grep dropbear)
  6. mstombs

    mstombs Network Guru Member

    Do you have to use full path for dropbear and killall? I recall cron doesn't assume path?
  7. ImGeo

    ImGeo Addicted to LI Member

  8. ImGeo

    ImGeo Addicted to LI Member

    I think cron/cru does work.

    # cru a test "45 12 * * * dropbear -p 22 -a"
    # ps | grep dropbear
    # killall crond
    (restart crond, to reload config, incase it's necessary)
    (shows nothing)

    after 12:45
    # ps | grep dropbear
    (shows dropbear)

    Problem is, when I restart the router, my cron jobs are gone :(
  9. ringer004

    ringer004 LI Guru Member

    Use the web GUI

    You can create cron jobs that stick via the web interface:

    Look under Administration -> Scheduler -> Custom 1,2,3
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