[ale] Comcast linux...

[Bob Toxen]

On Tue, Jan 06, 2004 at 05:14:36PM -0500, Mike Murphy wrote:
> DHCP grew from BootP, which is also a UDP protocol. If memory serves, 
> BootP is UDP because that's mostly how such LAN utility protocols were 
> done, way back when. UDP is probably the better choice anyway, at least 
> from an efficiency point of view, anyway. DNS, NFS, and a host of other 
> "early" protocols were all UDP based, at least initially, for similar 
> reasons. After all, who want's all that extra overhead of SYN'ing and 
> ACK'ing when you can just spew datagrams if you want to get an SPX 
> connection for your printer?
I agree that UDP is more efficient in many (most) client/server applications.
In the last two servers I created that used UDP to move large amounts of
data, I saw 2-20 times the bandwidth utilization.  I got 2 with a low-latency
network and saw 20 (or so) with a high-latency network.

In the first case, where I created a NFS server from scratch for a
non-UNIX OS, the guys that wrote the driver code came to me and claimed
my numbers were in error because they were too high because their TCP
numbers were half the speed.

> Mike
Bob


> Bob Toxen wrote:
> >On Tue, Jan 06, 2004 at 09:36:57AM -0500, Yu, Jerry wrote:
> >
> >>I have a RH linux hooked up to the cable modem (Motorolla surfboard 
> >>??4100).
> >>It always picks up IP/subnet/dns using DHCP just fine.  The RH has been
> >>upgraded from RH 6.1 all the way to 9.0. Hasn't got around to upgrade to
> >>Fedora yet.
> >>Make sure your firewall rules allows DHCP (67/68).
> >>I can give you the information once I get home. However, the IP you grab
> >>manually may conflicts with whoever gets assigned by Comcast's DHCP
> >>server...
> >
> >Actually, you probably do NOT need to enable DHCP (UDP 67/68) in your
> >firewall as dhclient (and almost certainly the other DHCP clients) put
> >the interface in Promiscuous mode to listen.  They need to do this because
> >otherwise the hardware will filter out DHCP packets as having someone 
> >else's
> >IP address as the destination.  Do "ifconfig" and look for the PROMISCUOUS
> >flag (unless you have one of the versions of RH that have a broken version
> >of ifconfig, in which case the script that ships with my book will tell.)
> >
> >Yet another reason why DHCP is a badly designed protocol.  Who created it
> >anyway?  The other reason is that it is UDP which is spoofable, rather than
> >TCP which is not with a decent stack.  Microsoft?
> >
> >Bob
> >
> >
> >
> >>-----Original Message-----
> >>From: Byron A Jeff [mailto:byron at cc.gatech.edu]
> >>Sent: Tuesday, January 06, 2004 7:26 AM
> >>To: Atlanta Linux Enthusiasts
> >>Subject: Re: [ale] Comcast linux...
> >
> >
> >
> >>On Mon, Jan 05, 2004 at 03:20:48PM -0800, Berlin Brown wrote:
> >
> >
> >>>I almost have my comcast cable modem setup.  I think I just need a 
> >>>primary
> >>>dns, nameserver using ips only.  Does anybody have the dns for atlanta
> >>
> >>from
> >>
> >>>comcast, emory area.
> >
> >
> >>That's an interesting question. Everything for comcast is set up via DHCP 
> >>right?
> >
> >
> >>>
> >
> >
> >>>I cant find it on the net.  And the people at comcast wont give it to me.
> >>>Redhat is supposed to pick it up, but it didnt?
> >
> >
> >>That's real interesting. Actually it just got more interesting as I 
> >>checked
> >>my smoothwall machine and it's acting as its own caching nameserver. So
> >>I don't have the address either.
> >
> >
> >>BTW the cc.gatech.edu College of Computing server will serve DNS addresses
> >>to anyone who asks. It's what I always use when I don't know the local 
> >>address: 130.207.3.207
> >
> >
> >>>
> >
> >
> >>>Funny thing, when the comcast tech came.  At first I never even thought
> >>
> >>you
> >>
> >>>needed a windows machine(havent installed a win machine in 2 years).
> >>
> >>Anyway
> >>
> >>>the guy went nuts over it.
> >
> >
> >>Not only typical, but it's in your Terms of Service.
> >
> >
> >>>I said fine, just leave the modem, 'We can't do
> >>>that, once you get windows up, we will send another guy out.'  
> >
> >
> >>Again the standard response.
> >
> >
> >>>B.S.!, just  leave the modem, Ill figure it out, then he left.
> >
> >
> >>It's unfair, but makes sense. Here's the facts of the matter:
> >
> >
> >>1) The techs only have limited training.
> >>2) The customers generally know nothing about computers and networking.
> >>Usually
> >>  this gives the techs an advantage, until they come across one of us. ;-)
> >>3) It costs money to train for another OS and....
> >>4) They can lose their jobs if they leave without it being set up.
> >
> >
> >>It's a tough life for us Linux folks, but in fact I and appreciate the
> >>policy because if they did train the Techs (both rolling and phone),
> >>the cost of service goes up.
> >
> >The service does not go up.  The $600 a year that one Linux user spends
> >is more enough to add two lines to the script that the Techs use.
> >
> >
> >>On the phone I always tell 1st level tech support that's it's a Windows 
> >>2000
> >>box. I patiently explain that it's the cable modem, not my machine. If I
> >>get to second level I ask "Do you want to hear the truth?". Usually they 
> >>do,
> >>but they don't flip out. I ask them what they are looking for and 
> >>translate.
> >
> >Yes, the only way I got the MediaMinusOne (that became ComCast) morons to
> >verify that they miskeyed my MAC address (despite my handing them a printed
> >copy) was by lying and saying that I hat Windoze95.
> >
> >
> >>I still find it interesting that no DNS info comes through...
> >
> >
> >>BAJ
> >
> >_______________________________________________
> >Ale mailing list
> >Ale at ale.org
> >http://www.ale.org/mailman/listinfo/ale

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