[cs615asa] troubleshooting (was: GHOST / CVE-2015-0235)

[Jan Schaumann]

Julian Sexton <jsexton at stevens.edu> wrote:
> Hi Professor,

Hi Julian,

Thanks for your email.  This gives me a good opportunity to help convey
a few lessons in communicating effectively via email.  (Don't take it
personally, you're just the first to offer me this segue.  My
recommendations below are for all students, not just you specifically.)

Since email is such a ubiquitous medium, we all regularly drown in too
many messages.  Our various mail clients and other programs try to help
us out by letting us sort mails in a meaningful way, for example by
subject or as a thread of messages that reply to one another.

As such, it's most useful to keep a separate email thread for different
topics of discussion.  If your message has nothing to do with "GHOST /
CVE-2015-0235", then using a new subject would be good.  Similarly,
composing a new message rather than replying to an ongoing thread would
help others sort your message correctly (most mail readers utilize the
In-Reply-To mail header to group messages).

Next, creating a reply and only adding new text on top of other text
leads to a proliferation of endless full-quotes.  In the future, please
refrain from this practice and only quote the text to which you are
referring / on which you are commenting.  (This goes back to the days of
Usenet, but proper quoting in emails is a good habit to develop.  See
also: https://www.netmeister.org/news/learn2quote.html)

Now all the formalities aside, when you want to report a problem it's
important to be precise and provide sufficient detail on what you're
trying to accomplish, what went wrong, and what you've tried to resolve
the issue.  So let's see:

> I'm having trouble accessing the linux-lab. Or rather, I can't access
> cs.stevens.edu at all - pinging it doesn't work

It's not quite clear what you mean here.  "cs.stevens.edu" is a domain,
not a host, so pinging it isn't possible/meaningful.  Do you mean you
cannot ping _any_ host under the cs.stevens.edu domain?

If so, that does not necessarily imply a problem by itself; it just
means that ICMP packets are not getting through to (or back from) the
given hostname.  Sometimes firewalls are configured to drop incoming
ICMP packets, which can make troubleshooting network problems a bit
harder than desirable.  (We'll discuss this in our class on Networking.)

> I can access cs.stevens.edu via proxy, so I can get
> on your website, but do you know if there's a way to do something similar
> for the linux lab?

SSH can be proxied just like any other protocol (although you can't use
a web proxy), but it shouldn't be necessary.

> I usually use putty to ssh in, but it's not even
> prompting me with a login screen.

Can you resolve the hostname?  What happens when you try to connect
using putty?  Does it take a long time and then terminate?  Does it
immediately terminate?  Does it give you any error or diagnostic
messages?

Sounds to me like an issue that IT should be able to help you with, but
when you find out what the problem was, please follow up here on the
list.

-Jan