Fishing around, can not get the answer for the problem. so ask it again....

I am under redhat linux 9 OS, I can browsing the website, and my IP address is 172.20.24.5. I tried to use xwin32 to access it from an windows environment, but it fails. After that i found i even can not successfully ping it.....I even set the security level to "NO firewall", but still can not...


anybody can give me some hits??

thanks
dejie

From what to what are you trying to ping? Across the internet or on the same network?

If it's on the same network, what's your other system's IP?

Do you get any error when trying to ping?

sorry...didn't clarify it clearly....

I am trying to ping the my computer with runing in linux from a computer with ID 155.69.144.156 . both 155.69.*.* and 172.20.*.* are under the schools VPN. because of the lack of IP address, so that for student in their hostel, using 172.*.*.*, all the computers are in the lab using class B address 155.69.*.*.......errrrr, i think it should not be a problem here, because it can ping my hostel computer if it is running in windows OS.

if my hostel computer running in linux

ping 172.20.24.5

request timed out
....
packetes: send = 4, Received =0, Lost = 4 (100% loss)

Ok... You are trying to ping your comptuer "U" from a lab computer "Lab."

The address of computer "U" is within the class b Private addressing scheme (172.16.0.0 - 172.31.255.255). Since you say that when computer "U" boots in Windows it workes fine then your school's IT staff must be routing between the two networks.

Given the output of your ping, I assume that "Lab" is running some sort of Win OS.

Are you able to ping the "Lab" computer from "U"?


Lab Computer : 155.69.144.156
Your Computer: 172.20.24.5

M: my hostel computer

.....i can not ping LAB successfully from M when booted with linux, It always hangs there:

#ping 155.69.144.156
PING 155.69.144.156 (155.69.144.156) 56(84) bytes of data

More stranged is that I tried to ping to other neighbour computers, like 172.20.33.51, the same result as above

Both of the two situations can be successfully pinged if M booted with windows

Another interested thing is that, the computer with IP 172.20.33.51 can successfully ping M when booted with linux.

so, any suggestion for it?

thanks a lot
dejie

The situation seems nothing i can do or i have to get a public IP address???

What is your routing table? and your arp table?

[root@localhost /]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
172.20.24.0 * 255.255.252.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 172.20.27.254 0.0.0.0 UG 0 0 0 eth0


[root@localhost /]# arp
Address HWtype HWaddress Flags Mask Iface
172.20.27.254 ether 00:00:5E:00:01:01 C eth0

[root@localhost /]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:80:48:29:F1:7B
inet addr:172.20.24.5 Bcast:172.20.27.255 Mask:255.255.252.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:25675 errors:0 dropped:0 overruns:0 frame:0
TX packets:2495 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4177740 (3.9 Mb) TX bytes:455559 (444.8 Kb)
Interrupt:5 Base address:0xcc00

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:347 errors:0 dropped:0 overruns:0 frame:0
TX packets:347 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:22346 (21.8 Kb) TX bytes:22346 (21.8 Kb)



above quite hard for me to understand, hope you guys can understand it well
and lead me to the right direction to fix it. thanks a lot!

dejie

strange situation.... when ping command hangs, does it say that all packets are lost when you stop it with "Ctrl+C" ??? Have you try a traceroute or something like that to determine where the problem is ?

I see some interesting things in your post....

First off, under your output from ifconfig for eth0

Your mask is 255.255.252.0 This tells me that your pool of available address on your netowork is large, but not as large as it started off. Normally an address starting with 172.20 would have a mask 255.255.0.0; however, your network admin changed yours to 255.255.252.0 What this did was steal bits from the "node" protion of a standard class B address scheme to allow him to "subnet." What does all this mean to you? Not a lot, but it tells me that you've got a network admin that knows what he's doing.

The other computer in the 172.20 address range was at IP 172.20.33.51. That address is outside your network, it's on another subnet entirely given that your address range stops at 172.20.27.255 (broadcast for your network).

I'd like to see your routing table on your computer when it boots in Win98. Type "route print" at a command line and post the output.

I agree with Oliv' that traceroute is the next step. I'd try from your comptuer under Windows to trace route to the lab machine. I'm thinking that your network has 2 ways out of it...

M : 172.20.24.5
|
|
|
------------------------->Other Campus IP Addresses ?.?.?.?
|
|
Internet
172.20.27.254

If this is the case, it should be apparent in your Win98 machine's routing table or via the tracert command. Type tracert 155.69.144.156 and note the first hop's address. If it's something other than 172.20.27.254 then we're on to something, if not it's back to the drawing board.

MrKnisely