Sendmail and POP3

[Magueta]

Hello everyone.

I'm curious about an occasional phenomenon that occurs when I try to retrieve my mail using POP3. I run my own server and I am the only one who can retrieve e-mail from my local network and nobody from the internet can send or receive e-mail from my server for security purposes (not that spammers and hackers don't try everyday anyway). Anyway, I'm running a RH Linux 9 server fully patched and running Apache, Sendmail, Samba, and IPtables to name the network services that interface with the network. The hardware is an HP Netserver LH3, dual PII 400s with 500 megs RAM, 2 RAID implementations (RAID 0 and RAID 5). Internally I have a 100 Megabit network and a Broadband connection to the internet.
Now to the problem; occasionally I open Outlook (which is on the local 100 Mbps network) and there are 2 or 3 accounts that are unavailable and I can't think of any reason why. The server is nowhere near its capacity and neither is the network. There are 10 separate accounts that I use for business purposes and all of them exist on my home server but they are the only accounts being used. Also, it isn't just once and then I could hit send and receive right after and it would be OK, the accounts are unavailable for awhile (not sure how long I haven't timed it yet). Note: they are not always the same accounts. Anyone have any ideas as to why those accounts might not be available?

Joe

[bufferman]

what do you mean by their not being available?
You can't access them?

Have you considered postfix intead of sendmail btw?

[Magueta]

I get the error message that the server is unavailable. If I wait awhile it comes back but I have to wait. I thought initially that it was that there were too many accounts at once but 10 accounts at once should be chicken feed for my server running Linux and on a 100 Mbps network.
Anything else?

PS: My choice of Sendmail was both laziness and prudence. Sendmail was already installed and there was more documentation available on the web for Sendmail than for Postfix. I realize the Irony that by choosing Sendmail out of laziness over Postfix I may have created more work for myself later on but, for the volume of mail I'm dealing with and that everyone other than my specific machine is blocked from accessing the server I didn't see any reason to deviate from the norm.
Why do you ask?

Joe

[bufferman]

I have beginner level experience with sendmail, but the popular (and logical) choice these days is postfix or qmail.

From my knowledge of these two. Postfix is more sendmail-like.

As for your problem. Check your firewall rules. I had a similar problem a long time ago and it was firewall related.

[Sawdusty]

Originally posted by bufferman
I have beginner level experience with sendmail, but the popular (and logical) choice these days is postfix or qmail.


Or exim.


(not that spammers and hackers don't try everyday anyway)


Hackers wouldn't ever do that. Crackers would.

[Magueta]

Originally posted by Sawdusty


Hackers wouldn't ever do that. Crackers would.

I disagree.
A hacker is not someone who doesn't break into systems, a hacker is someone who may or may not break into systems for non malicious reasons. ;)

From Webopedia for Crack:
(1) To break into a computer system. The term was coined in the mid-80s by hackers who wanted to differentiate themselves from individuals whose sole purpose is to sneak through security systems. Whereas crackers sole aim is to break into secure systems, hackers are more interested in gaining knowledge about computer systems and possibly using this knowledge for playful pranks. Although hackers still argue that there's a big difference between what they do and what crackers do, the mass media has failed to understand the distinction, so the two terms -- hack and crack -- are often used interchangeably.

(2) To copy commercial software illegally by breaking (cracking) the various copy-protection and registration techniques being used.


So a hacker still breaks into systems but they only do it to see if they can, not to steal or ruin anything. Just like most people I know who enjoy Linux (opinion here) I've been known to hack a little myself so I'm not a complete stranger to the distinction between Hacking and Cracking.
Cheers!

Joe

[Sawdusty]

You're right, my original statement was not my original intended meaning. I do it all the time. :-D

I meant to say something like "this isn't hacking, it's cracking". Further, *most* crackers aren't hackers, and most hackers don't do stuff like that on a more than casual basis because it's not usually terribly productive.

I cite:
http://www.catb.org/~esr/jargon/html/C/cracker.html
http://www.catb.org/~esr/jargon/html/C/cracking.html

Note specifically from the cracking definition: "Contrary to widespread myth, this does not usually involve some mysterious leap of hackerly brilliance, but rather persistence and the dogged repetition of a handful of fairly well-known tricks ..."

Meaning, IMO, that "hackers" that break into systems to see if it can be done are not challenging themselves enough.

Dusty