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Shipboard outages of network can happen when the ship turns.  This can be unpredictable.  I use this technique to "set and forget" transfer data over HiSeasNet, using a combination of rsync, SSH and the Bourne-Again SHell (BASH) on a UNIX-type system.  You'll need to set up password-less SSH keys to do this.

1. Create an ssh-key for your shipboard host, if you haven't already done so.  `man ssh-keygen` for more info on this.  This is a potential security risk, so you should understand the caveats and benefits.

chmod 0600 ~/.ssh/id*
cat ~/.ssh/ | ssh me@myShoreServer "cat - >> ~/.ssh/authorized_keys"

2. Login to a shore-based server, use the faster link to stage the data:

ssh me@myShoreServer
wget -N -nd http://someServer/some.file

3. On the local shipboard system, use rsync to grab the data in a loop that will execute forever until rsync succeeds.  The -P flag will move resume a partially transferred file, so once data is moved once, it will stay on board and be updated; the -c flag will ensure the shore-side and shipboard final file(s) checksum to be the same.

while ! rsync -Pcrtz myShoreServer:/dir/to/data/some.file /local/target/dir; do echo "`date -u` Restarting rsync..."; done

If you want the data to show up, but not hog all the bandwidth while you leave this alone for hours (days?), use the --bwlimit flag.  --bwlimit is calculated in kiloBytes per second (kBps), not kilobits per second (kbps), so a value of 2 kBps per second is 16 kbps.

while ! rsync --bwlimit=2 -Pcrtz myShoreServer:/dir/to/data/some.file /local/target/dir; do echo "`date -u` Restarting rsync..."; done
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