some networking questions, I'm slightly confused

Gregory Nowak gnowak1 at uic.edu
Thu Dec 6 22:52:19 EST 2001


In kernel 2.4.16.
Greg


On Thu, Dec 06, 2001 at 07:56:42PM -0700, Darrell Shandrow wrote:
> Hi Gregory,
> 
> On which Kernel version's source tree are you finding this information?  I 
> do not find it in 2.4.6.
> 
> Thanks.
> 
> At 08:44 PM 12/6/2001 -0600, you wrote:
> >I am trying to do something like serial line load balancing, but with nics.
> >It is described in /usr/src/linux/Documentation/networking/bonding.txt
> >.
> >Greg
> >
> >
> >On Thu, Dec 06, 2001 at 07:11:14PM -0700, Darrell Shandrow wrote:
> > > Hi Greg,
> > >
> > > Hmmm, this talk about bonding I am not understanding...  Are you trying to
> > > multihome with two different service providers?  Please advise; I'm
> > > apparently missing something.
> > >
> > > Thanks.
> > >
> > > At 12:17 PM 12/6/2001 -0600, you wrote:
> > > >Yes, sort of.
> > > >I'll have to talk to the guy running the service here when he gives me my
> > > >second
> > > >connection, and see if I'll get another ip address or not, and if he 
> > knows
> > > >if his router will support  bonding.
> > > >Greg
> > > >
> > > >
> > > >On Wed, Dec 05, 2001 at 10:00:36PM -0700, Darrell Shandrow wrote:
> > > > > Hi Greg,
> > > > >
> > > > > Good deal; I'll be glad to do what I can to help, especially with a
> > > > > specific implementation.  Did you get your answers regarding the 
> > two NICs
> > > > > and the outside addressing?
> > > > >
> > > > > Regards.
> > > > >
> > > > > At 09:56 PM 12/5/2001 -0600, you wrote:
> > > > > >Thanks for the info even though I knew 99% of that.
> > > > > >I will be in touch if I need more help.
> > > > > >Again, thanks for a very good explanation (it's certainly better 
> > then I
> > > > > >could've done (grin)).
> > > > > >Greg
> > > > > >
> > > > > >
> > > > > >On Wed, Dec 05, 2001 at 08:19:57PM -0700, Darrell Shandrow wrote:
> > > > > > > Hi Greg,
> > > > > > >
> > > > > > > I have stayed out of this until now because I haven't really had
> > > > any time
> > > > > > > to respond properly.  My days are usually quite long
> > > > lately.  Anyhow, I am
> > > > > > > a sys admin for a regional ISP; perhaps, I can help you.
> > > > > > >
> > > > > > > A domain is registered through a registrar like Network 
> > Solutions or
> > > > > > > register.com.  When the domain is registered, part of the required
> > > > > > > information includes the IP addresses for the primary and 
> > secondary
> > > > name
> > > > > > > servers.  This information is then added to what are known as 
> > the root
> > > > > > > servers, which tell the entire world which primary and 
> > secondary name
> > > > > > > servers know how to answer lookup questions about your domain.  In
> > > > other
> > > > > > > words, the root servers delegate authority to the specified 
> > primary and
> > > > > > > secondary name servers to answer questions concerning your domain
> > > > > > > name.  You could run one or both of these name servers yourself 
> > or have
> > > > > > > someone else do DNS.  It sounds like you are having someone else do
> > > > > > primary
> > > > > > > and secondary DNS.  As I'm sure you already know, DNS is the 
> > domain
> > > > name
> > > > > > > system, which points domain names to IP addresses, and which 
> > allows
> > > > us to
> > > > > > > do neat things like browse to www.foxnews.com and send mail to
> > > > > > > nu7i at azboss.net instead of having to know all kinds of awful IP
> > > > addresses
> > > > > > > just to perform the simplest of functions on the Internet.  So, 
> > DNS
> > > > points
> > > > > > > a domain name to an IP address, but how does it work?  DNS 
> > information
> > > > > > > about a domain name is handled by name servers in the form of zone
> > > > > > > files.  Your domain exists as a zone file on the primary name
> > > > server, and
> > > > > > > the secondary name server is usually set up as a slave to the
> > > > primary.  In
> > > > > > > other words, the secondary name server gets its information 
> > (the zone
> > > > > > file)
> > > > > > > from the primary name server and holds onto it, just in case the
> > > > primary
> > > > > > > name server is unavailable for some reason.  The domain name 
> > system is
> > > > > > > really a very large, world wide distributed database.  A domain 
> > name
> > > > > > > contains various types of information which is managed in the 
> > form of
> > > > > > > various types of records.  The first type of record is SOA, which
> > > > stands
> > > > > > > for start of authority.  This just specifies your primary and 
> > secondary
> > > > > > > name servers.  You see, if things were set up a certain way, your
> > > > primary
> > > > > > > and secondary name servers could actually delegate authority 
> > for your
> > > > > > > domain to still other name servers, but this is not common
> > > > > > > practice.  Another important record type is the A record.  This 
> > is the
> > > > > > > address record, and your domain could have multiple A records,
> > > > > > depending on
> > > > > > > how many subdomains you have set up.  For example my domain name
> > > > servers
> > > > > > > have an A record for shandrow.com which points to
> > > > > > 206.124.184.77.  There is
> > > > > > > also another A record for borg.shandrow.com, a subdomain, which 
> > also
> > > > > > > happens to point to the same IP address, though it could just 
> > as easily
> > > > > > > point to another IP address.  Another somewhat related record 
> > type is a
> > > > > > > CNAME, which stands for canonical name.  These records are used 
> > like
> > > > > > > aliases to point subdomains to other domains.  For example, I 
> > did use a
> > > > > > > CNAME record to point www.shandrow.com to shandrow.com, which 
> > means it
> > > > > > also
> > > > > > > has the IP address 206.124.184.77.  Yet another important record
> > > > type is
> > > > > > > the MX record.  MX stands for mail exchanger.  E-mail software 
> > uses
> > > > these
> > > > > > > records when figuring out how to deliver e-mail on the 
> > Internet.  These
> > > > > > > records, numbered by priority, tell mail delivery software 
> > where mail
> > > > > > > should go when destined for a particular domain.  For example, my
> > > > first MX
> > > > > > > record priority for shandrow.com (which is MX 10) points to
> > > > > > > borg.shandrow.com.  That is ultimately pointing to the Sendmail 
> > server
> > > > > > > which runs on the IP address 206.124.184.77.  But, again, this
> > > > could have
> > > > > > > just as easily pointed to any Sendmail server which was 
> > configured to
> > > > > > > accept and deliver mail for the shandrow.com domain.  Additional MX
> > > > > > records
> > > > > > > can be defined so that, if the server specified in the first
> > > > priority MX
> > > > > > > record is unavailable for some reason, mail delivery software will
> > > > try a
> > > > > > > second, third, fourth and so on server until it can deliver the
> > > > mail.  I
> > > > > > > could, if configured properly, have a MX 20 pointing shandrow.com
> > > > to yet
> > > > > > > another Sendmail server, which would be able to receive mail for
> > > > > > > shandrow.com in the absence of the primary mail server.
> > > > > > >
> > > > > > > Finally, there is reverse DNS.  This does the reverse of the 
> > domain
> > > > name
> > > > > > > system; it translates IP addresses back to domain names.  You
> > > > definitely
> > > > > > > want to have your DNS administrator set this up for your domain,
> > > > because
> > > > > > > certain FTP sites, web sites and other types of services on the
> > > > Internet
> > > > > > > use reverse DNS information for security purposes; they want to 
> > see
> > > > that
> > > > > > > your forward DNS and reverse DNS point to the same place, or they
> > > > may also
> > > > > > > want to verify that you have a domain which is or is not 
> > registered
> > > > in a
> > > > > > > certain part of the world.  In my example, performing a 
> > nslookup on
> > > > the IP
> > > > > > > address 206.124.184.77 will tell you that it reverses to
> > > > > > borg.shandrow.com,
> > > > > > > which is a valid subdomain pointing to that same IP address.
> > > > > > >
> > > > > > > Anyhow, this will either help you or confuse you.  Please let me
> > > > know if I
> > > > > > > can help you with specifics.
> > > > > > >
> > > > > > > Regards.
> > > > > > >
> > > > > > > At 06:38 PM 12/5/2001 -0600, you wrote:
> > > > > > > >Well, I'll actually be running a mail server for the building in
> > > > which
> > > > > > I live.
> > > > > > > >Instead of being regularly payed, my current connection will be
> > > > free, and
> > > > > > > >I'll get a second free connection
> > > > > > > >They're running t1 over here through this HP networking gizmo that
> > > > > > > >plugs into the phone jack, and has an rj45 jack on it.
> > > > > > > >
> > > > > > > >
> > > > > > > >The reason I'm asking about the dns stuff is because
> > > > > > > >when I told the guy that I've looked at the mail admin docs, 
> > and am
> > > > > > > >seriously considering running the server,
> > > > > > > >his response to me was:
> > > > > > > >"so, I'll need to get you a domain with primary and secondary dns
> > > > > > servers."
> > > > > > > >I said yes to this, but am carious about how his dns servers 
> > will know
> > > > > > > >where I exist
> > > > > > > >since he didn't ask for the name of my box.
> > > > > > > >I guess when he tells me he's got things set up,
> > > > > > > >my first question to him will be,
> > > > > > > >"what name do the dns servers know my machine by?"
> > > > > > > >
> > > > > > > >He's macroslop licensed, but not meaning to brag,
> > > > > > > >I get the impression that I may know more then he does without a
> > > > license.
> > > > > > > >
> > > > > > > >In case some of you reading my post now are remembering a few of
> > > > my other
> > > > > > > >posts, I decided
> > > > > > > >that getting my own domain name wasn't worth it.
> > > > > > > >He said that I could run a small web server here if I want. So, I
> > > > don't
> > > > > > > >think he'd
> > > > > > > >have a problem with me running it as http://mybox.domain.
> > > > > > > >
> > > > > > > >This whole thing started when I got my service, and he came 
> > here to
> > > > > > get it
> > > > > > > >all setup.
> > > > > > > >Not only was he impressed that I was the only one in the building
> > > > so far
> > > > > > > >running anything other then windblows, but that it was Linux.
> > > > > > > >After my configuring tcp/ip both in windows and in Linux while 
> > he just
> > > > > > > >watched me do it and gave me my ip address and all the other 
> > stuff,
> > > > > > > >I asked if I would get a mail account.
> > > > > > > >He said no, because there is no body to run one yet.
> > > > > > > >Then he tentatively asked if I would be willing to perhaps do it,
> > > > I said
> > > > > > > >I'd read the mailadmin docs and think about it,
> > > > > > > >and you know the rest.
> > > > > > > >
> > > > > > > >He's also looking to hire someone to run apachee.
> > > > > > > >But, I'm not touching that for now (grin).
> > > > > > > >Sorry for the long and personal post, but since Geoff asked,
> > > > > > > >I figured that some other people on this list may be wondering
> > > > > > > >why I'm asking theese questions, some of which may sound
> > > > > > > >dumb, but are for the most part so that I could make sure that 
> > what
> > > > > > > >I know is actually correct.
> > > > > > > >Greg
> > > > > > > >
> > > > > > > >
> > > > > > > >On Thu, Dec 06, 2001 at 09:29:48AM +1000, Geoff Shang wrote:
> > > > > > > > > On Tue, 4 Dec 2001, Gregory Nowak wrote:
> > > > > > > > >
> > > > > > > > > > 1. Say there is a primary and secondary dns servers on a 
> > domain
> > > > > > > > called mydomain.
> > > > > > > > > > Say also that there is a machine called mybox.
> > > > > > > > > > Also, I have ip addresses for primary and secondary dns
> > > > servers on
> > > > > > > > mydomain.
> > > > > > > > > > Assumming all of the above, and assuming that I have
> > > > permission to
> > > > > > > > officially be on mydomain which is a valid internet domain,
> > > > > > > > > > what do I do on mybox so that it would be resolvable
> > > > > > > > > > as mybox.mydomain on the net?
> > > > > > > > >
> > > > > > > > > Nothing.  It's the primary and secondary DNS servers that 
> > control
> > > > > > how your
> > > > > > > > > host is resolved, not your box.  As long as mybox has the IP
> > > > > > address that
> > > > > > > > > ns1.mydomain.com and ns2.mydomain.com think it has, you 
> > should be
> > > > > > good to
> > > > > > > > > go.
> > > > > > > > >
> > > > > > > > > > 2. Say that I have to nics with 2 static ip address for the
> > > > outside
> > > > > > > > world.
> > > > > > > > > > How do I set things up so that my box would use both
> > > > > > > > > > nics for outside access instead just either one nic or 
> > the other?
> > > > > > > > >
> > > > > > > > > As Chris said, what comes in where will depend on what 
> > address it
> > > > > > is sent
> > > > > > > > > to.  What goes out where depends on a few things.  If you 
> > want to
> > > > > > use one
> > > > > > > > > interface to access a particular host or network, you can 
> > set up a
> > > > > > route
> > > > > > > > > accordingly.  If you want to access everything with both, you
> > > > might
> > > > > > be able
> > > > > > > > > to put 2 default routes (i've seen it done but don't know if it
> > > > > > works and
> > > > > > > > > if it's supposed to work).  I saw you've been looking at
> > > > bonding which
> > > > > > > > > might also work, but I don't know about it.
> > > > > > > > >
> > > > > > > > > Can I ask, why you have 2 NICs?  Is it just to get 2 
> > addresses or
> > > > > > are you
> > > > > > > > > connected to 2 networks?
> > > > > > > > >
> > > > > > > > > Geoff.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
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