Question about ifconfig

when i use if config:
linux:~ # ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1729 errors:0 dropped:0 overruns:0 frame:0
TX packets:1729 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:147516 (144.0 Kb) TX bytes:147516 (144.0 Kb)

ra0 Link encap:Ethernet HWaddr 00:02:44:93:24:4F
inet addr: 192.168.0.68 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::202:44ff:fe93:244f/64 Scope:Link
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:81459 errors:0 dropped:0 overruns:0 frame:0
TX packets:64563 errors:6 dropped:6 overruns:0 carrier:0
collisions:20813 txqueuelen:1000
RX bytes:96893951 (92.4 Mb) TX bytes:8807000 (8.3 Mb)
Interrupt:11
It says that my IP on the LAN is 192.168.0.68
Now when i want to ping the hosts on my LAN:
linux:~> nmap -sP 192.168.0.0/24

Starting Nmap 3.95 ( http://www.insecure.org/nmap/ ) at 2006-02-24 08:03 GST
Host 192.168.0.1 appears to be up.
Host 192.168.0.64 appears to be up.
Host 192.168.0.66 appears to be up.
Host 192.168.0.68 appears to be up.
Nmap finished: 256 IP addresses (4 hosts up) scanned in 3.687 seconds
And as you can see 192.168.0.68 is up on the LAN , my question is how can it happen? did i ping myself? how am i mentioned as a live host, and am I really 192.168.0.68?

--thanks

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did i ping myself?

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Yep..

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how am i mentioned as a live host,

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Your host responded to an ICMP echo request..

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and am I really 192.168.0.68?

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According to your ifconfig (ra0) output, yes...

Okay, so when i want to ping the LAN one of the pings is sent to back to me via the router, and one of the live hosts must be me. begrepen. Really funny! cause i knew that the machines are running windows and always tried to figure out why the OS scan gave me linux!

-thank you !

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RX packets:81459 errors:0 dropped:0 overruns:0 frame:0
TX packets:64563 errors:6 dropped:6 overruns:0 carrier:0
collisions:20813 txqueuelen:1000

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To digress for a moment, I assume from this that your local network is connected with a hub? Given the decently high # of collisions (20813) versus the mount of transferred traffic (tx+rx) (146022) or around 14% you might benefit from going out and getting a cheap switch ;)

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so when i want to ping the LAN one of the pings is sent to back to me via the router

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If I am not mistaken, the ping doesn't go out to the router
but stays on the local machine, just as if you pinged the
loopback address 127.0.0.1 (localhost).
Somebody correct me if I'm wrong.
:cool:

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Originally posted here by rcgreen
If I am not mistaken, the ping doesn't go out to the router
but stays on the local machine, just as if you pinged the
loopback address 127.0.0.1 (localhost).
Somebody correct me if I'm wrong.
:cool:

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Sounds correct, but I wouldn't know how to be certain without asking Someone Smarter Than Me™

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Originally posted here by DutchGeek
Okay, so when i want to ping the LAN one of the pings is sent to back to me via the router, and one of the live hosts must be me. begrepen. Really funny! cause i knew that the machines are running windows and always tried to figure out why the OS scan gave me linux!

-thank you !

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Couple of minor, niggeling points here. But I am in a mood and MUST point them out. Is it really a router? Or, as nebulus200 has supposed, is it a hub? Maybe a couple of cheap tin-cans-and-some-string? Communications via osmosis?

When discussing network problems with hardware involved, you need to be specific. A router is NOT a switch which is NOT a hub. Many vendors (Linksys, D-Link, etc.) have been known to mis-label or simplify commercial products, much to the dismay of the network professionals amongst us. I sincerely doubt you have a router sitting there. It may be one of those home gateway devices, which is essentially a router and switch in one.

As for it being funny...no. It's not. The command you are executing is performing EXACTLY as you configured it to.

nmap -sP 192.168.0.0/24

You asked it to ping 192.168.0.0 with netmask 255.255.255.0. The system you ran this scan from happens to be within that range, so the command sent a ping to the IP address that happened to belong to your local system. Nothing funny about it...it did what you said. *shrug*

RC,

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If I am not mistaken, the ping doesn't go out to the router
but stays on the local machine, just as if you pinged the
loopback address 127.0.0.1 (localhost).
Somebody correct me if I'm wrong.

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You're right about the 127.0.0.1 never leaving the nic it's designed as the hardware loopback test and should never even touch the line.