[ale] GATech mirror problems - from the admin

[Michael Still]

ftp.ale.org runs vsftpd  and has this setting:
max_per_ip=2

It's httpd.conf has this in it:
RedirectMatch (.*)\.iso$ ftp://ftp.ale.org$1.iso

So to get an iso you need to use ftp and are subject to the per ip
limit.  There are no
other limitations configured.

>From Florence, Italy.  Ciao.

This limits concurrent connections.

On 4/25/07, Neil Bright <neil.bright at oit.gatech.edu> wrote:
> Hi folks,
>
> As the admin of the GT linux mirror, I'd like to comment on some of
> the issues people have been raising.  Hopefully, I can at least
> provide some explanation as to the behaviors people have been seeing.
>
> General FTP problems -
> I'm using vsftpd with PASV enabled (the default behavior).  Please
> ensure that you use ftp clients that understand this portion of the
> protocol.
>
> DNS issues -
> These reports seem to stem from the use of the ftp-
> linux.cc.gatech.edu name.  GTLib is no longer housed within the
> College of Computing, but rather from our central campus IT
> organization - the Office of Information Technology.  The CoC
> maintains their own DNS infrastructure and I can't vouch for it's
> reliability.  The *.gtlib.gatech.edu names use our central campus DNS
> infrastructure.  Another portion of my responsibilities at GT is
> campus hostmaster, so I'm a bit more comfortable making guarantees
> about these names.  If you are having problems with them, please let
> me know.  Output from tools like dig and the contents of resolv.conf
> will be especially useful in these situations.  ;)
>
> General performance problems -
> We've been getting pretty hammered lately...  We're on the Fedora YUM
> lists, we host debian and ubuntu, we're part of rsync.us.gentoo.org,
> we host Suse, Mandrake and Mozilla.  The There's an architecture
> diagram here [1] for those interested.  A couple of the switches have
> been rearranged since I last updated the graphic, but the important
> parts are correct.  Of course, this means that the MRTG graphs are
> incorrect now....  *sigh*  However, there is also a Ganglia instance
> at [2].  In addition to the usual stuff, I also have additional
> gmetrics tracking the number of active apache, vsftpd and rsync
> connections.  There are also some bits in there related to NFS as well.
>
> For the last while, the default 256 connections on all three of the
> apache front end machines have been in use.  Likely, the performance
> issues people have been seeing lately are latency issues while
> waiting to establish a connection.  (At least, this is my current
> theory, feel free to shoot holes.  :)  Many of these connections have
> been coming from the dreaded "download accelerators", often times
> with 20+ connections coming from the same IP address.  I understand
> that NAT on the other end of the pipe will look like this, but I am
> unaware of a programatic way to distinguish between NAT and abuse.
>
> For now I've increased the MaxClients setting, but my current long
> term thinking is to employ some sort of per-address connection
> limiting.  If anybody has suggestions on how to do this I would love
> to hear from you.  I have RHEL4 with the provided apache, vsftpd and
> rsyncd on the hosts.  All four hosts are attached to the same Cisco
> 2970 with a Cisco 6509 (Sup2 & SFM) router running IOS 12.2 and Cisco
> FWSM running 2.3(4) firewall context.  The hosts could be moved to a
> 4948 if that would make a difference.  (Due to topology changes, this
> will likely happen anyway.)  Donations of memory for a SunFire v20z
> would always be appreciated as well.  *grin*
>
>
>
>
>
> [1] - http://www.gtlib.gatech.edu/gtlib.pdf
> [2] - http://www.gtlib.gatech.edu/ganglia
>
> +=======================================================================
> =+
> Neil Bright (neil.bright at oit.gatech.edu)                    (404)
> 385-6954
> OIT - Academic and Research Technologies / Georgia Institute of
> Technology
> 258 Fourth Street, Rich Bldg, Rm 266 / Atlanta, GA  30332-0700
>
>
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> Ale at ale.org
> http://www.ale.org/mailman/listinfo/ale
>


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