Cisco Weight Loss Addendum

After the revelatory nature of the information I shared earlier this week, I felt on top of the world, but that illusion quickly shattered when I attempted to upgrade some of our newest (but still autonomous) access points, only to have my tftp requests time out.  A quick ? showed me that I could instead use scp (which has made appearances on this blog before), but the syntax was left as a mystery to me.  I have finally found the syntax, though (hint: it’s not quite the same as the normal *nix command) and have had considerable success upgrading our remaining autonomous units with that method.

Whereas with tftp, you simply entered the server address followed by the path to the file (relative to the tftp server folder), the Cisco version of scp is a bit more complicated.  My main tripping point was discovering what the file path for the image being downloaded was relative to.  I assumed it would start at the root of the filesystem, / but instead the path is expressed relative to the home folder of the username specified.  I don’t know if using ../ will let you back out of your home folder, but it’s simple enough to copy the image to your home folder.  So, to use scp to download an image from your machine to a Cisco access point, you would use

archive download-sw /reload /overwrite scp://username@server/path/to/image.tar

where the image path is relative to the home folder of username.

That’s all.  Happy scp-ing!

Finding the Sticky Wicket with ntop

Oh, yeah! Pie charts, baby!

While I still haven’t gotten many chances to really put it through its paces, I really love a lot of aspects of the MR12 Meraki sent me.  One of my favorite features is the ability to get a lot of granular detail on the network traffic clients are getting through the AP.  There are places where raw data is fine, but a lot of the time, I want a nice visual representation just so I can get a quick idea of what I’m working with.  This is especially true when we have weird hiccups or slowdowns on our network in certain areas.  Unfortunately, I don’t have Meraki APs everywhere, so I can’t just pull up a lot of sexy data and quickly figure out what’s up.  I’d really love to be able to do that, though.

So what does a sysadmin do when there’s a need but not a solution he knows?  Google, duh.

And what does google give me?  It gives me ntop.  If you are a knowledgeable user and not just a luser, you have probably used top before to find out what processes are using the most of your memory and processor at any given time.  Well, ntop is something like that, only for networks.  But, more than that, it can give you nice graphical representations of your data through a web interface.

Having just run across ntop this very hour, I haven’t dived into the man pages for it yet, but I have written a long command chain so that I can read the things without standing in front of my Linux terminal, and, because sometimes I just want to write a long command, here’s what I did:

man -t ntop > ntop_man.ps && ps2pdf ntop_man.ps && rm ntop_man.ps && scp -P 22 ~/ntop_man.pdf [user]@[lappy]:/Users/[me]/Documents

So there.

(Of course you can expect me to post more about ntop as I dive in and find out what it can do for me and, by extension, what it might be able to do for you.)

When You’ve Left Your Papers at Work

A little gem I learned today when needing to get a file from a remote system that I’d sshed into onto my local machine so that I could manipulate it while offline: the scp command.

There are a lot of switches for scp, but if you’re trying to get a file to or from a remote machine, or even between two remote machines, both of which you are able to ssh into, here’s the syntax:

scp -P 22 [user@source.machine.address.if.remote:]/directory/of/file/to/copy [user@target.machine.if.remote:]/target/directory

In the above example, the -P flag is indicating the port (in this case, we’re using port 22 because we’re logging in using ssh).

If you’ve typed everything correctly, you’ll then be prompted for the password of the user at the remote machine (or the first one, if you’re moving files between two remote machines). After entering everything correctly, you should see a new line indicating the current file being transferred, the percentage transferred (this will update live), number of bytes transferred, transfer speed, and elapsed time. If you’re just copying a small text file, this will flash by faster than you can really comprehend, and you’ll be deposited back at the command prompt before you know it.