IP of a network device via cross connect rj45?

[PBMAX]

Ok, IT pros, help me out here if you can... I was wondering if there is a way to get a network device to tell you its IP (static IP) using a cross-connect cable. Basically using the cross-connect to connect a laptop directly to the applaince.

The reason.. We have network appliance and unless some has the sence to label the machine we need a rj45 to serial converter to connet to the applaince via its propriatary serial port... Just trying to simplify (i hope) potential problems for my self down the road. Mostly, I'd just like to know if it can be done and how if it's not to dificult to get into here...

Aslo I do not see a lable with the MAC address on the device... wasn't really expecting to...

 

[getut]

Simply being connected to a "network" (existing on the network) whether it is a full blown network or just a crossover cable between two network devices isn't enough for the node to have an address.

So to make that easier to understand, you either have to manually give each of the devices an IP address or there must be a server to do it for you (DHCP or BOOTP).

If you have no way to administer the other device from a console or something like that or you have forgotten a password to a device, the best you can hope for is to get a promiscuous mode network analyzer and run it. If there are only your known device and the other one, any traffic you see on that 2 machine network that isn't coming from yours will be from the other one. The network analyzer should be able to grab the IP and MAC address.

Ethereal is a free open source network analyzer that you can download. You will also need WinPCap as your packet driver to go along with it.

 

[PBMAX]

getut, thanks for the links I'll check tham out... I kind figured the answer would be as you stated. I should state, more clearly that the device its self would already have a static IP previously assigned at some point. The 4 I have here do but are unknown and of course the Laptop uses DHCP as our sever would tell it what to use... ThoughI could give a Temp Static IP... For this pupose.

</font><font color="blue" class="small">( Simply being connected to a "network" (existing on the network) whether it is a full blown network or just a crossover cable between two network devices isn't enough for the node to have an address.
)</font>

exactly the problem... I'm having...

</font><font color="blue" class="small">( If you have no way to administer the other device from a console or something like that )</font>

for good or ill the console is ran via a browser so you need the ip to connect to it's html page... But some kind net stumbler is a good idea I'll check ou the links... Thanks much...

Whish there was some way send a generic ping...or CQ? as in HAM radio... via telnet of hyper terminal...

 

[jim_wilson]

What kind of device is it? Can you connect to it thru a serial port and use Hyperterminal to get into it? If so there should be a utility on the device to tell you it's network information. On Unix/Linux based devices you can get the network info out by doing a "ifconfig -a" - on a Windows based device the command is "ipconfig -all"

 

[PBMAX]

Jim, I'd imagine it runs on a Linux platform, though I can't swear to it... Unfortunatly it is a custom built device produced for our use with 2 of our commercial lighting controls we sell... While it can be connected via serial it uses a rj45 connector on its MB and I have not idea what the pin out would be yet. Though we are getting a crossover from them... this week I think... the device is still in testing at this point with a few in the field...

Mostly I was just curious... I could have sworn I've done this before,at least with win based products, but hadn't thought about the issue of it being on Linux and my laptop being XP.... So I doubt they woud talk on a crossconnect any how... While I'm pretty sure I could plug just the 2 of them into a router by them selves and get the info... I was looking at it hoping to find a simple soultion for us field folks... Without haveing carry yet another pound of wieght to our already limited travel kits.(we fly lots)...

That and I was told it can't be done via RJ45...

can you say 2ble dare!!! I just can't pass that up... ;- )-

 

[DaNag]

If I understand things correctly, it should be pretty simple - if you know the network information for the segment the appliance is plugged into. If you don't know this information, it's easy to get - if there's a DHCP server on the network the appliance is plugged into. Just plug your laptop into the network (configured for DHCP), open up a command prompt, and run an ipconfig /all.

Once you have the network info, simply temporarily conifgure your laptop with a static IP for the same network/subnet the device is on, hook up the crossover cable, and run a scan for live addresses.

Can't give you a personal recommendation for a Windows tool - I use Linux for such tasks. I've read good things about Angry IP scanner - it's free, might be worth trying.

 

[getut]

Thats what I was getting at... although I went into more detail because:

1) He didn't say the device had ever been connected to any other network.

2) Even if it had, and the ethernet feature had never been used, there is no guarantee that it is properly configured for the network it is attached to.

IP scanning is great if you are relatively sure a device is somewhere in a given, somewhat small range.

Promiscuous mode scanning for chatter on a small network with a device that can be physically isolated on that network would probably be faster. Just disconnecting and reconnecting the ethernet cable to the device would likely cause some ARP announcement traffic at the very least.

 

[DaNag]

</font><font color="blue" class="small">( He didn't say the device had ever been connected to any other network.)</font>

Perhaps a bad assumption on my part, but when he stated it had a static IP address, that means one of two things to me:

- It has the factory default address. In which case, none of this is necessary, as the manufacturer could advise what it is. Or...

- It has been configured with IP info already for SOME network.

I was assuming these appliances were hooked up and functioning, at some point in time, to a known network - if not, you are correct, my IP scanning method wouldn't be ideal.

Regardless, on second thought, I think we're both making this far too complex. The serial access method is much easier, has none of the IP related pitfalls or complex software requirements, and is most likely relatively easy.

More likely than not, there is nothing propietary about the RJ45 serial connector on the appliance; they are pretty standard. I run across them all the time, and I have the same simple setup for all of them:

- Female DB9 to female RJ45 adaptor
- 6' silver satin cable, male RJ45's each end
- DB9 null modem adaptor

Some devices require the null modem adaptor, some don't. The whole thing can be had for about $10, and easily stows in a laptop case.

I bought my DB9 to RJ45 adaptor pre-wired, but here's a link to schematics showing the wiring standard, including schematics for making DB9 or DB25 to RJ45 adaptors.

 

[PBMAX]

correct getut, the device is not connected to a network at this time... and even of it were unless the <font color="red"> static IP </font> that is already assigned at the factory during testing is really odd as compared to that of the networks range, as you mentioned.

The idea I'am after is plugging directly into it in the field with out a DHCPserver or router. Using a cross-connect Eithernet cable (ie. a null modem cable for either net) for direct NIC to NIC... Laptop to Appliance... again no DHCP server or router. If it were 2 pc's it be no problem...

<font color="green">Just talked to a programmer fot the appliance it runs Qnix(spelled?) with J9vm from IBM on that.... Assentually a java based app. we view via EI... as a console... The typical out of the box Ip range is 192.168.1.140 to 192.168.1.149... these 4 boxes are not in that range so until we get the eithernet to serial converter this week ... I thought I'd play</font>


Can you see how much fun this could be for an electrician in the field??? This is really just a personal pet project I was tinkering with... <font color="green">You really shouldn't tell me can't.</font> But any ideas are appreciated.... What are the odds that the appliance would still have its factory set static IP a year later??? and who would remeber what they changed it to??? You can usually Borrow,Bum or steal a crossconnect cable from any IT person... But were do you get a pinout specific eithernet to db9 from...? RadioS... yeah right... ;-)

 

[Hypernix]

PBMAX,

If the device can be setup with an IP address, then that RJ45 connector is hooked up to an Ethernet interface. (Unless there is more than one connector). Now you can buy a converter to go from Serial to Ethernet which will cost you a couple hundreds $ and I don't think this will get you anyware since you need to talk to an Ethernet interface not a serial interface. Now if this device realy has an ethernet interface (that RJ45 connector) then the MAC address has to be on a label somewhere outside or inside the machine. Usually it's right next to the RJ45 connector.
With the MAC address and the crossover cable, you can assign an IP address (force it) to the device using the ARP or RARP (reverse arp) command. I forget which on it is I would have to do some checking here. After that youre all set to connect to the web interface with you web browser. Of course like to others said, the PC a the other end of the crossover cable has to be on the same subnet.

Hypernix