Remote PC Problem

[pjphilli]

Hi

I have previously extended the control of my astro PC located outdoors near my mount/scope to indoors via a RJ45 crossover cable. I am using
Windows XP Professional.

I have recently changed the astro PC and I am having difficulty getting
the ethernet connection working. Here is the situation:
1. Ethernet port working normally as indicated in Device Manager;
2. ipconfig indicates: IP Adress 169.254.51.212
Subnet mask: 255.255.0.0
Default Gateway: nil
I can internally ping this number successfully.
3. Local Area Connection Status shows No Connectivity (the RJ45 cable
is plugged in at both ends and both PCs are active.) It says that the problem "occurred because the network did not assign a network address to the computer".
Attempt to Repair (to get a new IP address) reports: "Attempt to Repair
but Windows could not do this."

Is the IP address different from the Network Address?
Any suggestions?
Cheers Peter

[mithrandir]

So that end is using autoconf. Is the other end doing that too? Does the PC at the other end have two network connections? The crossover to the astro and another to the 'net? If it does I don't think Windows will autoconf the x-over interface if there is a non-autoconf interface.

What does that mean? You can ping it from itself, or from the house?Sounds like the analysis above might be correct or close to it. Rough up a diagram of all network cables and devices like I did in my examples.Yes. "Network Address" is the MAC address (media access - a level 2 concept). "IP address" is a logical address (a level 3 concept).

You can apply a static address to each end of the PC-PC link. Do not use the same subnet as any other network interface.

Do have a router or switch you can plug the astro PC into? This is 100% easier to get right than a x-over between PCs, but requires either normal cables (not x-over) or gigabit ethernet ports which sort out the cables all by themselves.

Andrew

[OICURMT]

I'll assume that you have two and only two computers connected via a crossover cable.

So, let's begin the inquisition!

Step)

0) Open DOS windows on BOTH computers (via "cmd" under Start/Run for XP or Start/Search Programs under W7
1) On both computers, please type the command ipconfig /all
2) Copy and paste the results here...

Then I can guide you to the next step.


A couple of items you may want to check... your post has a good clue.


This leads me to believe that one of your computers is expecting a DHCP server to assign it an addy... you should make sure that both computers have static IP addresses in the same class range (Class B in your example). You will also need to check your firewall setting between the computers (turn it off temporarily to make sure it is not interfering).

OIC!

[mithrandir]

169.254.51.212 is strictly speaking not a class B address, even with the class B netmask. 169.245.1.0-169.254.254.255 is the IPv4 Link Local address block as defined in RFC 5735 and RFC 3927. See Wikipedia (http://en.wikipedia.org/wiki/Private_network#Link-local_addresses) if you don't want to read the RFCs. Link local autoconf is the fallback for when DHCP fails.

Not getting a suitable address is the symptom. The solution depends on how the network hangs together. A firewall should not be stopping DHCP or autoconf. A diagram would help.

Andrew

[OICURMT]

You are of course correct... I was concentrating on the netmask (and using the term generically), rather than the fact that it's a private sequence/link local. I'll try to be more specific in the future.

In any case, a firewall can indeed be stopping the DHCP request depending on what ports and protocols are blocked (UDP 67/68 in the case for DHCP).

Except from /etc/services follows:

bootpc 68/tcp dhcpc # BOOTP client
bootpc 68/udp dhcpc
dhcpv6-client 546/tcp
dhcpv6-client 546/udp
dhcpv6-server 547/tcp
dhcpv6-server 547/udp
dhcp-failover 647/tcp # DHCP Failover
dhcp-failover 647/udp # DHCP Failover
dhcp-failover2 847/tcp # dhcp-failover 2
dhcp-failover2 847/udp # dhcp-failover 2
qip-qdhcp 2490/tcp # qip_qdhcp
qip-qdhcp 2490/udp # qip_qdhcp
All the best
OIC!

[pjphilli]

Thanks for all the advice. These have given me a few things to look into.
My "network" is very simple - just two stand alone PCs (no other networks)
connected together by the RJ45 cable.

Answering your specific questions Andrew:
- When I say internally ping I mean on each PC to ping its own IP address. However, I cannot ping from one PC to the other as the remote IP addresses cannot be found.
- No I do not have a router. The above simple network worked well before
I changed the server PC (the one at the mount) where the problem is at present.

Cheers Peter

[pjphilli]

Hi OIC

I now have the ipconfig/all files which are attached as server.jpg and remote.jpg.

The server is the end giving problems as outlined in my previous post.
The Local Area Connectivity indicates "no connectivity" for the server.

The remote Local Area Connectivity indicates "connected".

I notice that the Subnet Mask for the server is 255.255.0.0 whereas
for the remote it is 255.255.255.0. Is this a problem?

Cheers Peter

[pjphilli]

Hi OIC

I see that the file names do not appear on the attachments to my previous post.

The server is the one with the IP address 169.254.51.212
the remote IP address is 192.168.1.3.

Cheers Peter

[OICURMT]

Peter:

Your server (hostname: p-b8efe62f25644) is assigning an address in a different block to your remote computer (hostname: peter2). The easy way to fix it is as follows:

If you are good with command lines, you can issue the following command as administrator on your server to fix your problem (in a DOS window).


netsh int ip set address "local area connection" static 192.168.1.1 255.255.255.0 192.168.1.1 1
This will assign your server with an IP address of 192.168.1.1, which your remote computer on 192.168.1.3 can access.

If you are not good with command lines, then you will have to get into the network device settings (the same panel that has the "repair" button). Go to the "General" tab and click on "Properties". From there click on "Internet Protocol (TCP/IP)", then click on "Properties". A panel where you can set a static IP address will appear. You should be able to tackle it from there...


BTW: While you will be able to ping back and forth, you may not be able to query the computers by hostname. The simple solution is to setup IP/names in the host file (located under /windows/system32/drivers/etc)


OIC!
P.S. The second way to fix the problem using route tables... would not recommend it since you only have two computers in a LAN.

[mithrandir]

The server is getting 169.254.51.212 because it is looking for DHCP and not finding a server.
The remote is getting 192.168.1.3 because it has been given that as a static address.

OIC's answer will solve your problem, but I don't find giving PCs or servers addresses at the start of the address range good network design. I configure DHCP to not allocate from there. My policy is for network devices to use the first few numbers. I'd be more tempted to make it something like 192.168.1.4

Windows boxes should be able to find each other by using NetBIOS name resolution even if the names are not in the hosts file. Unless you've disabled that which I find unlikely.

You might consider renaming p-b8efe62f25644 to something a bit more human readable. That's buried somewhere under "My Computer".

As for adding static routes - that is a "when all else fails" solution. Don't go there.

Andrew

[pjphilli]

Thanks OIC and Andrew
Have just changed the IP address as you advised and all is now working OK.
Easy when you know how! I have copied your advice and placed it in my computer folder for possible future use.
Great - I can again control my mount from the comfort of my lounge room -
now for some clear skies - a permanent fix in this respect would also be appreciated!:rofl:
Cheers Peter

[OICURMT]

No problem Peter... more than one way to skin a cat. I'm just glad I could help.


As for Andrew's comment on the overall DHCP range, he is correct in that most routers reserve the first IP address for assigning to client which request an IP. So if you ever purchase a router or ADSL modem you *may* have to change the servers IP to a higher number.

As for route tables... I personally don't see any problem with them. I use them to segregate my kids portion of the house from the adult side of the house. Keeps it very clean and my kids having LAN parties does not interfere with my side of the LAN.


Difference of opinion I guess, oh well :shrug:

OIC!

[mithrandir]

If the objective is to keep the kids LAN parties isolated put them on another LAN or VLAN. If you want to cut them off from the rest of the house or the internet, restrict their access at the router. The only justification I've every known for static routes is when normal routing protocols (eg RIP, OSPF) are broken by something like firewalls. Been there. Done that.
Probably, but I have been doing network stuff for over 10 years. Getting it right the first time saves hair pulling, finger pointing and bad language later.

Andrew

[OICURMT]

:rofl:

I guess I'm old school... been doing it this way since the 90's... (read, early 90's :()

Man, I'm getting old :sadeyes:

[Visionoz]

Oh, OICURMT, in that case I must be older school than you - been doing it before the 80s!!:P Started in San Jose, CA

Cheers
Bill

[OICURMT]

w00t! Us old timers gotta stick together!...

I cut my teeth on MVS in the late 70's (at the IBM research center in Niwot, Colorado when I was in high school)... transitioned to DEC(VAX)/VMS in my 1st years at university and ended up in the JCL/Cray world and DomainOS by the early 90's...

Had an Apollo DN10000 as my home server once my company was done with it by 1993... loved the machine, but honestly, my washer was smaller and used less power... :) took up Minux the same year... Linux soon followed when Slackware "came of age" .... (i.e. it fit on only 30 1.4Mb floppy disks... :lol:)

[Zaps]

You kids make me feel old.

[OICURMT]

I concede to my elders... :rofl:

[mithrandir]

Luxury.

Programmable calculator while at school ('60s). Machine code on IBM 1460. APL. FORTRAN on Univac and CDC3600/3300/3200/Cyber. COBOL (yuck). CDC sysprog. PDP/11. MVS sysprog. Slackware since it was 0.9something and 13 floppies, and I'm just about to upgrade to 13.37. Most versions of OS/2. Not counting consumer products like Apple II, 2c, MacII, every version of Windows.

Who's next for one-up-manship? :)

Andrew

[OICURMT]

Only person I can think of is my father... slide rule king-o-da-hill...

85y and still kicking it... can't use a PC to save his soul, but still knows how to slide rule... ha ha :thumbsup:

He asked me about my goto scope, so I told him... he then asked, "Why can't you just point it at what you want to see?" .... :question: