NFS help (.. is definitely needed)

[Otto Haliburton]

> -----Original Message-----
> From: redhat-install-list-bounces at redhat.com [mailto:redhat-install-list-
> bounces at redhat.com] On Behalf Of Greg Julius
> Sent: Sunday, August 28, 2005 7:36 PM
> To: Redhat Install List
> Subject: RE: NFS help (.. is definitely needed)
> 
> I broke this up to understand it and reply in parts.
> 
> >not wanting to get into a heavy discussion on this issue, I will just
> state
> >this simply.
> >
> >My ISP assigns me a IP address, I have a router and through
> >the DHCP my computer is assigned a local IP address and since I have
> >connected to my local address I have up to 5 local IP addresses(could
> have
> >many more if I liked) under this standard each of the 5 IP addresses are
> >translated to go out the one address assigned by the ISP.
> 
> This router sounds like a standard router which you can get from Linksys,
> NetGear, et. al.  In comes one wire (the WAN from your ISP) and out goes
> one
> or more wires (the LAN).  Many even have an access point built into them
> to
> give wireless capability to the LAN.  These things are quite amazing when
> you think about it.  They have multiple Network ports, they accomplish
> many
> networking chores, they provide address translation and some firewall
> capabilities and even wireless.  All in a box between $25 and $125.  Easy
> to
> use and easy to set up.  Reliable as the day is long.
> 
> <warning>
> Discourse on DHCP, WAN, LAN, NAT, and SPI forthcomming, skip if you know
> all
> about it.  But since this thread is turning into a general education on
> networking, it feels right to do this.  I hope I'm not insane and showing
> too many flaws in my understanding.  Everyone please jump in where I have
> boned it up.
> </warning>
> 
> Most ISPs providing high-speed internet give a dynamic address.  If you
> are
> providing services to the internet (say a web-site or an email server)
> then
> you will probably need a static IP.  There are a few reasons where you
> might
> need one even if you don't provide services to the internet.  Some
> providers
> will only give you static addresses and some providers will never give you
> a
> static address.
> 
> In any event, the router has the ability to "speak DHCP" to the ISP and
> request an IP from the ISP (they come out of the box configured that way).
> They can also be configured to respond to a specific static ip if that is
> what your ISP gave you.
> 
> Some routers have the ability to report to one of the "dynamic DNS"
> providers (like DynDNS JEff mentions) the IP address assigned by the ISP.
> This gives the ability for the internet at large to find your router even
> though it doesn't have the decency <grin> to stay at a given address.
> Static IP assignments don't need the dynamic DNS solutions.
> 
> The configuration of the WAN side of the router, either static or dynamic
> provides some much needed information:  The network address & subnet, the
> router's address as seen from the internet, the router's gateway IP to the
> internet, and a couple (usually two or more) Domain Name Servers for
> Domain
> Name resolution.
> 
> So, for the sake of this discussion, let's say that the WAN IP address
> (the
> address of the router as seen from the Internet) is A.A.A.34 (make up your
> own numbers for A.A.A <grin>  For the literal, the A number is between 0
> and
> 255).  This WAN IP could have been dynamic or static.  The important thing
> is that there is one.  There will also be the other values as mentioned
> above.
> 
> That covers the WAN side.  Now for the LAN side.
> 
> The router usually provides DHCP services to the devices attached to the
> LAN
> by wires or wireless.  The router can also accept devices that have a
> fixed
> IP address.
> 
> On the LAN side, you would commonly get a set of addresses starting with
> 192.168.0.x or sometimes 192.168.1.x - I've seen both - if the address
> were
> generated by an out of the box router by DHCP.  x is usually a value
> starting at 100 and going up.  Supposing you have two devices attached,
> then
> one could be 192.168.0.100 and another could be 192.168.0.101.  If you
> configure the DHCP service provided by the router you can end up with
> anything.  Note that the router also has a network address on the LAN,
> usually 192.168.0.1.  This is the address of your router as seen from
> inside
> your network.
> 
> OK, now we have a wire on the right (The WAN) and wires on the left (The
> LAN).  The WAN side of things can be thought of as the Internet.  The LAN
> side of things can be thought of as the internal network or Intranet.
> 
> >From the point of view of the internet, all of your computers have the
> same
> address, Namely A.A.A.34, the address of the WAN IP on your router.  The
> crowd on the internet never sees your internal 192.168.0.x address.
> 
> So, how does your computer attached at 192.168.0.100 carry on a
> "conversation" with a computer on the internet?  More to the point, how
> does
> a response from something on the internet get to  your PC if all of the
> PCs
> on your internal network appear to have the same address?  That's NAT's
> job.
> 
> NAT is Network Address Translation.  ** Note:  I am about to really
> simplify
> here to avoid confusing on exactly how this works  **  When you start a
> "conversation" with an Internet service (say your email at your ISP) your
> PC
> says I want to talk to IP B.B.B.B (which is the IP provided by some DNS
> server for the name of your email server on your ISP).  The first thing
> your
> computer does is look up to see where it should send it.  It doesn't know
> so
> it sends it to the gateway for your network.  The gateway will usually be
> the router (remember the 192.168.0.1 address from earlier?).
> 
> The router then takes note of which computer the message came from and
> where
> it was going (it remembers), it then translates the internal network
> address
> into a variation of the A.A.A.34 address and then sends the message along
> on
> to the next hop which will be the gateway address of the WAN.
> 
> When the reply comes back, the router looks up where it came from and
> where
> it was going (the variation of the A.A.A.34), "untranslates" the addresses
> and sends the message to the appropriate computer.
> 
> That's NAT in a nutshell.
> 
> Now what about when somebody sends something to A.A.A.34 out of the blue?
> Usually, because it doesn't know who it was intended for (can't find
> anything in it's memory about it) it throws it away.  This feature is a
> part
> of what is called SPI (Stateful Packet Inspection).  When you send
> something
> out (an outgoing packet), the router remembers who, what, when, how.  When
> a
> reply comes back (an incoming packet) the who, what, when, and how is
> compared to prior outgoing packets looking for a match.  If it doesn't
> find
> it, and the router isn't configured to do something special with it, then
> it
> just throws it away.  This is a basic firewall feature and helps to
> prevent
> uninvited outsiders from getting into your network.
> 
> That's SPI in a nutshell.
> 
> 
> >When it assigns
> >me the one IP address it assigns my IP address to two DNS IP addresses
> and
> >it also assigns a gateway.
> 
> A bit of care here on the terminology.  Your ISP assigned your router a
> network address & subnet, an IP, and a gateway and INFORMED it of two DNS
> addresses that it could use for retrieving IP addresses from Domain names.
> It didn't send anything to the DNS for you.
> 
> >The ISP can change the IP address it assigns to
> >me(this assignment is a dynamic assignment) anytime it wants and it will
> be
> >transparent to me because the DNS to which this IP is assigned is updated
> >with the IP address and since it is transparent somebody in China can
> still
> >send a message or connect to my network and they don't need to have the
> new
> >IP address that is assigned.
> 
> Sigh.  Not exactly right.  Yes, the ISP can, will, and does change the
> address which gets assigned to your router.  It does not send anything to
> the DNS.  Period.  Your router may send something to a DynDNS type
> service,
> but you can rest assured that your ISP did not.
> 
> For clarity, I would like to find out why you think your address is
> getting
> assigned to the DNS so somebody in china can get to you?
> 
> I'm not denying that they can send you messages via email or even via some
> instant messanger or something of the sort, but not by the name of your pc
> which is inside your internal network.
> 
> >Now on my local network I can have the same
> >setup.  I can have my own DNS server that I assign my local IP to and it
> >resolves the issues for my local network.  On local networks arbitration
> >goes on and somebody declares I'm the boss and I will handle all of this
> >info and if he drops out then the arbitration happens again and somebody
> >else becomes boss, etc etc.
> 
> This sound extremely like NETBIOS processes and is not a function of
> TCP/IP
> at all, nor even of the internet.  Are you sure you are not confusing the
> two as they are very similar in purpose and function?
> 
> Yes, you can set up a DNS on your internal network.  All it takes is a
> host
> to run it on.  Yes, you can put in your DNS the IP addresses of the
> machines
> on your network.  This is manually done usually.
> 
> There are even some routers which now contain am mDNS which works in
> conjunction with their internal DHCP and gives a "Dynamic DNS" ability.
> The
> Dynamic part is the Address assignment from DHCP and a real-time update of
> the DNS of that assignment data.  But even in this case, the mDNS is being
> updated by the DHCP and not by the host.  I know it sounds like splitting
> hairs, but of such is the network made.
> 
> 
> The rest of the statement is not DHCP nor DNS and sounds like NETBIOS.
> 
> >The DNS declares himself to be the boss of the
> >5 computers on my local and does all of the resolutions for my network
> and
> >communicates with the outside world to resolve the issues.
> 
> This would definately be NETBIOS. It isn't DNS.  While DNS may give name
> resolution services, it doesn't declare itself boss.  The Network setup
> data
> provided by DHCP or by manual configuration says where to go look for name
> to address resolution.
> 
> >One of the
> >issues that you mention is true for domains like .com, .net, and etc.
> ???
> 
> >but
> >that is only part of the answer the other part is the routing and routing
> >tables and these are important in the address resolution.
> 
> Actually, routing and routing tables have nothing to do with name to
> address
> resolution.  Nor DHCP.
> 
> Routing and routing tables are the underlying mechanism for getting a
> packet
> from point Address A.A.A.A to B.B.B.B  This involves a lot of things like
> address resolution protocol and transmission metrics and RIPs and such
> which
> I won't even begin to touch.  My understanding of that is shakey at best.
> 
> DHCP is the assignment of an internet address (your WAN or LAN addresses
> for
> example) to a particular host or device.  This device may be on your
> internal network or perhaps your router address from your ISP.
> 
> DNS is concerned with mapping a name (POP.EXAMPLE.COM) to an internet IP
> address (the A.A.A.A or B.B.B.B).
> 
> 
> >While I don't
> >disagree with you completely.  There are definitely holes, I am not a
> >expert, but you can check any ISP assignment to see that the structure I
> >presented above is alive and working.
> 
> Jeff makes excellent points about the internet and shows a keen grasp of
> the
> issues facing dynamic domain name service issues on the internet as a
> whole.
> I think Jeff was thinking mostly about the internet at large in his
> response.  LANs have a bit more flexibility and that is where this
> discussion originally started.
> 
> Regarding your claim that that's how it works, I just don't see it.  I
> don't
> know which part of the internet you are using, but mine doesn't work the
> way
> you describe.  Neither the parts inside my three LANs nor the parts of the
> internet I interface with connecting my LANs to the internet and while
> providing web hosting to my clients.  I get the feeling you are mixing
> NETBIOS and DNS and DHCP and such in a big mash.
> 
> >SNMP is a part of what you presented
> >so I am not completely positive about all of this but there is chaos
> going
> >on when you decide to send a message, cause a route has to be setup and
> it
> >is this arbitration between the DNS that determine how to setup this
> route.
> 
> I did a search on the original message and don't find SNMP mentioned.
> Simple Network Management Protocol is a tool used to manage the devices on
> the network and to diagnose the network when it is down or not working
> correctly.  I don't really use it yet as my needs have been simple to this
> point.  Soon, but not now.
> 
> -g
> 
> 
you have gone through what you think is a heavy analysis, let me now give
the the simplest and the skinny about how you isp works, when your router
comes up it goes to the DHCP for the ISP and get assigned a IP address this
ISP address is usually assigned to computername.state.city.isp.domain in the
dns now you can go from there