Daniel W. Ottey on 14 Jul 2009 06:30:46 -0700

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Re: [PLUG] favorite admin tools

Thanks for the mention of htop.  I just downloaded it from EPEL.  Very slick!  Won't be able to roll it out to all my servers, but its nice to play with.

On Mon, Jul 13, 2009 at 4:06 PM, James Barrett <jadoba@jadoba.net> wrote:

Welcome to the wonderful world of system administration!  Run while
you still can!

A few very valuable tools that I have picked up on my previous journeys:

htop - real-time process information display doohickey.  It has the
same concept as 'top' - it shows information like CPU time and memory
consumption of all currently running processes.  htop has friendlier
features, and is simply easier for me to understand as compared to

iftop - a command run by a superuser (root) to identify traffic
flowing through a machine's network interface.  Essentially, it shows
real-time information about current connections to the machine.
Information like the source and destination IP address and ports,
current transfer rate and cumulative traffic for a specific
connection, and total traffic for the entire interface.  If you are
trying to track down a traffic hog on your network, then this can be
very useful to have on a transparent bridge/firewall or router.

netstat - very useful for showing a list of current network
connections, although it can do much more.  Learn the flags: 'netstat
-tuna' ... t - show TCP connections; u - show UDP connections; n -
show numerical addresses and port numbers to avoid DNS lookups; a -
show 'all' listening and non-listening sockets.  Also useful, is the
'p' flag, for showing process ID numbers, and 'e' for extended output
(use it twice for more extension).

screen - very valuable. it does a lot. I use it mostly to keep my
shell sessions persistent.  Here's a quick scenario as an example.  I
ssh to my server, and run 'screen', which kindly gives me a bash
prompt.  I start doing work on the command line.  My roommate will
usually come home when I'm about half-way through a compile.  He will
turn on his Vista-powered laptop, which, unbeknown to him, will
promptly start downloading updates that he will never apply.  He
doesn't care that the connection is already painfully slow, and he
just starts downloading an hour-long podcast anyway.  This chain of
behavior inevitably puts too much load on the old and predictable
linksys wireless router, which stops working and drops all connections
to the Internet until it is reset...  If I wasn't using screen, the
connection would time out, bash would exit, my compile would be
ruined, and the local police would be puzzled as to how all that blood
could have possibly gotten on the ceiling and floors without a single
drop ever hitting any of the walls.  Thankfully for everybody
involved, no murder is necessary because the compile is still running!
 After resetting the router and scolding my roommate with the
newspaper, I simply reconnect with ssh and run 'screen -r' to reattach
the screen session.  It might complain about the screen already being
attached, but i can simply detach it from the old, lingering session
with 'screen -dr'.  I could even connect to the remote server from two
different machines, and work from two terminals at the same time by
running 'screen -x'.

I agree with Douglas, munin is a nice tool.  It runs in the
background, periodically gathers information about the machine and
spits it into a pretty set of graphs.  Some useful information could
be gleaned from those graphs after a glitch, such as memory, disk
usage and CPU temperatures during the few hours preceding the
malfunction.  It can take note of network traffic rates, which can
shed at least a glimmer of light on a situation in the event of a
DDoS.  Otherwise, it can simply be used to gauge heavy load times, as
Douglas has mentioned.  Some people have told me that munin is a
memory hog, but I do not see that to be the case, although maybe I
have simply not deployed it extensively enough.

Hope that help,s and good luck!

James Barrett

On Mon, Jul 13, 2009 at 2:10 PM, Ron Kaye Jr<rekaye1005@verizon.net> wrote:
> hello all sys admin types
> do you have a set of favorite linux admin tools that you would recommend?
> like nagios, etc
> Ron
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