arp problem in pinging host



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  • 4. adding static route to vmware image ...
    not sure if this is the right group ... can you help please i have a windows box running a linux vmware image with a 192.168.x.x ip which cannot be changed. The windows server which it runs on has a 10.0.2.x address The server from which i want to connect to the 192 address has an ip of 10.0.1.x and i can ping the 10.0.2.x address ok so the route is ok up to there. what do i need to do to finish the route to the 192.168.x.x address ? many thanks.
  • 5. Which News-fields are needed ?
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Re: arp problem in pinging host

Postby Allen McIntosh » Wed, 18 May 2005 03:24:03 GMT

[Removed comp.protocols.tcp-ip since it isn't relevant]

I guess I should have asked for ifconfig -a in the same post - 
newsreader won't let me go back and look at original.  Anyway
OK but redundant, since it is covered by the default route.
So eth0 has an IP addr of 192.168.1.x where x != 1, and is connected by 
a crossover cable to eth1 on R1.  eth1 on R1 has address 
OK so far?

eth1 had address and is connected to A.
eth0 has address and is connected to R2.  More on this later.
eth0 has address and is connected to R1 via crossover cable? 
  I see several things wrong with this.  First, R1 and R2 send default 
traffic to each other.  Second, it would be more usual to use a netmask 
of for the network.  Third, I don't understand 
how the 192.168.1 entry got here or what it is supposed to be doing. 
(There are two wildly different networks assigned to the same interface 
with no gateway on either entry.)  The entry looks funny too. 
  What is the address of eth1 supposed to be?

I think you need to sit down with a piece of paper and draw your 
network.  For each network segment (each crossover cable is one) write 
in the interface name, the addresses of each interface, the network 
address, the broadcast address and the netmask.  Then double check that 
the routing tables and addresses (output of ifconfig -a or equivalent) 
match the diagram.

Similar Threads:

1.arp problem in pinging host

    I have pc hostA with connected to pc R1 with
eth0: and eth1: via crosscable when i ping from
hosta to R1 request packet goes to R1 but R1 generates packets with
srcip= and destination ip of R1's eth1= and hosta
unable to receive reply packet from R1. But if i ping from R1 to hosta
packet always goes to hosta and receives reply at R1. What can be the
reason is that arp cache problem or what else?
       When i send ping packet to R1 from hostA, the arp analysis on my
both Linux machines shows that when i did arp -a on hosta and found
output that
R1( at <incomplete> on eth0
and on R1 nothing is displayed.
        When i send ping packet to hostA from R1, the arp analysis on
my both Linux machines shows that when i did arp -a on R1 and found
output that

Address               HWtype  HWaddress           Flags Mask
hosta                 ether   00:08:F1:43:62:91   C

and on hosta
Address               HWtype  HWaddress           Flags Mask
R1                    ether   00:08:F1:43:61:C1   C

whats wrong in hosta linux machine?

2.Strange network problems - pings to host are fine, pings from host fail

Sorry for the long post - I've tried to outline the symptoms of my 
problem, and what I've tried to fix it.

I'm having some networking problems with a PC running an old version of 
Red Hat (kernel 2.2).  The PC came with a machine we have bought 
second-hand - as far as I know, everything was working before the 
machine was moved to our company.

To keep things simple, we have the Red Hat machine connected to a 
Windows XP machine that came with it, with only a simple switch in 
between.  Each machine is set up with a fixed IP address on the same 

 From the XP machine, I can ping the Red Hat machine reliably and 
quickly.  From the Red Hat machine, pings to the XP machine /generally/ 
fail - typically there are about 80%-90% failures.  Those pings that 
don't fail, are fast (reply time about 1 ms).  On the XP machine, it's 
easy to see the packet counters showing packets in and replies out.  On 
the Red Hat machine, ifconfig shows similar packet rx and tx counts, and 
zero error counts.

arping to the XP machine from the Red Hat machine is reliable and fast.

When we try a browser on the XP machine and address the web server on 
the Red Hat host, there is generally a long pause (perhaps minutes), 
then suddenly the page appears.

We have tried using another Linux box in place of the original XP 
machine, with the same results from the Red Hat system.

We have tried replacing the cables and switch, with no effect - given 
that arpings are working perfectly it's hard to see how it could be a 
hardware problem.

I'm not very familiar with Red Hat or a 2.2 kernel (my experience is 
mostly with Debian and related distros, and with 2.4 and 2.6 kernels). 
But "ipchains -L" shows no firewalling (everything accepted), "ifconfig" 
and "route -n" have the expected setup, and I could not stop anything 
unexpected with "sysctrl".

One of my colleagues will try a different network card this evening.

Any ideas or tips would be much appreciated.  We've tried pretty much 
every sensible idea we can think of, so I'm ready to listen to any crazy 
or unlikely tricks.



3.pinging to neighbour host problem

 I am running ethereal on linux on pcs with pc1 with ip
address= and pc2 with ip= I am pinging from
pc1 to p2 but sometimes packet goes normal way and sometimes i think
frame corrupted. Following my capture znalysis ON PC2. First Frame is
corrupted why? frame5 correctly received.
   what is the reason i am not able to receive frame correctly
   Does following packet makes entry in ifconfig anyalysis. I check but
no counter increased on PC2.
    Neither packet counted as RX packets nor dropped why?

 eth1      Link encap:Ethernet  HWaddr 00:08:A1:43:61:F5
          inet addr:  Bcast:
          RX packets:33 errors:0 dropped:0 overruns:0 frame:0
          TX packets:29 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:3494 (3.4 Kb)  TX bytes:2246 (2.1 Kb)
          Interrupt:9 Base address:0x9c00

No.     Time        Source                Destination
Protocol Info
      1 0.000000    40:00:40:01:b6:54     45:00:00:54:00:00     0xc0a8
 Ethernet II

Frame 1 (98 bytes on wire, 98 bytes captured)
    Arrival Time: May 20, 2005 15:57:13.599959000
    Time delta from previous packet: 0.000000000 seconds
    Time since reference or first frame: 0.000000000 seconds
    Frame Number: 1
    Packet Length: 98 bytes
    Capture Length: 98 bytes
    Protocols in frame: eth:data
Ethernet II, Src: 40:00:40:01:b6:54, Dst: 45:00:00:54:00:00
    Destination: 45:00:00:54:00:00 (45:00:00:54:00:00)
    Source: 40:00:40:01:b6:54 (40:00:40:01:b6:54)
    Type: Unknown (0xc0a8)
Data (84 bytes)

0000  45 00 00 54 00 00 40 00 40 01 b6 54 c0 a8 01 fa
0010  c0 a8 01 0a 08 00 df 9d 52 0e 00 01 22 bf 8d 42
0020  1e 4e 0d 00 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13
0030  14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23   ............
0040  24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33
0050  34 35 36 37 00 00 00 00 00 00 00 00 00 00 00 00
0060  00 00                                             ..

Frame 5 (98 bytes on wire, 98 bytes captured)
    Arrival Time: May 20, 2005 16:12:42.872068000
    Time delta from previous packet: 177.629913000 seconds
    Time since reference or first frame: 182.659884000 seconds
    Frame Number: 5
    Packet Length: 98 bytes
    Capture Length: 98 bytes
    Protocols in frame: eth:ip:icmp:data
Ethernet II, Src: 00:08:a1:43:62:91, Dst: 00:08:a1:43:61:f5
    Destination: 00:08:a1:43:61:f5 (
    Source: 00:08:a1:43:62:91 (CnetTech_43:62:91)
    Type: IP (0x0800)
Internet Protocol, Src Addr: (, Dst Addr: (
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 84
    Identification: 0x0000 (0)
    Flags: 0x04 (Don't Fragment)
        0... = Reserved bit: Not set
        .1.. = Don't fragment: Set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 64
    Protocol: ICMP (0x01)
    Header checksum: 0xb654 (correct)
    Source: (
    Destination: (
Internet Control Message Protocol
    Type: 8 (Echo (ping) request)
    Code: 0
    Checksum: 0xdf9d (correct)
    Identifier: 0x520e
    Sequence number: 0x0001
    Data (56 bytes)

0000  00 08 a1 43 61 f5 00 08 a1 43 62 91 08 00 45 00
0010  00 54 00 00 40 00 40 01 b6 54 c0 a8 01 fa c0 a8
0020  01 0a 08 00 df 9d 52 0e 00 01 22 bf 8d 42 1e 4e
0030  0d 00 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15
0040  16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25   ..........
0050  26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35
0060  36 37                                             67

4.problem configuring network ("host" works, "ping" doesn't)


I just downloaded and installed my very first OpenSolaris... and have
problems with the very basic things like configuring network.

Overall, connectivity works, I can ping remote hosts using IP addresses.

Trying to ping using hostname (i.e. ping doesn't work -
ping says that the host is unknown.

On the other hand, "host" returns a correct IP address -
which proves that DNS is set OK in /etc/resolv.conf.

What did I miss?
I noticed I had to correct /etc/nsswitch.conf (to use dns for hosts),
but other than that, I've no idea what I'm missing.


5.Ping and ARP on both Win and Linux in Python

Hi, this is my question:

I want to know if several switch (about 50) in a big lan are up and then 
know their MAC addresses to do a list that contains host name, ip and mac.
I know only the range of their IP addresses (the host name it's simply 
to know using socket.gethostn.

The first idea it's to ping all ip, parse the response and then execute 
the command "arp -a" and parse the response.
However this way depends on the operating system and the ping response 
depends too from the language.

Another way it's to open the main page of the switch and parse the HTML 
code where i can find the MAC address.
However this way depends on the particular brand's switch.

I know (or better i think) that there is a third way: make ping and arp 
building the packets with socket and so on (but i dont have understand 
in what way do this).

Any suggestion?

(i've already search in google, found many sources but a lot of them 
don't works or don't do what im trying to do...)


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