What's wrong with ARP? DHCP? - Networking

This is a discussion on What's wrong with ARP? DHCP? - Networking ; HI ALL, I have a home network composed of a Windows XP SP2 PC, a Fedora 7 Linux PC and a MFC-8660DN network printer. A linksys switch is working as a hub for my AT&T DSL modem and my home ...

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Thread: What's wrong with ARP? DHCP?

  1. What's wrong with ARP? DHCP?

    HI ALL,

    I have a home network composed of a Windows XP SP2 PC, a Fedora 7
    Linux PC and a MFC-8660DN network printer. A linksys switch is working
    as a hub for my AT&T DSL modem and my home network. And there is a
    "dhcpserver.exe" running as SYSTEM process on the Windows PC; My
    "dhclient" task is running on the Linux PC.

    At the beginning I downloaded a free dhcp server and assigned an IP
    address to MFC printer (since I didn't know how to configure the
    Windows dhcp service), After I saw printer got the IP address then I
    removed it and the dynamic IP address mysteriously stayed in the
    printer until now (I don't know why it doesn't expire, I didn't set it
    as permanent).

    Problem: Now I found the Windows PC can ping the Linux PC correctly
    ("ping" from windows) but Linux can't get the ping reply("ping" from
    Linux). Then I tried "arping" from Linux PC and eventually I got the
    ping reply.

    I have added Windows PC's IP and MAC with "arp -s" on my Linux PC
    MANUALLY every time when I start Linux. I know it stays in the ARP
    cache only. when I use "arp -a" to show all IP links in Linux, I show
    two other IP addresses assigned automatically for my switch and my
    printer, but not for my Window PC(which is MANUALLY added in).

    I have left my Linux firewall open for all the traffic. And Ethereal
    on Windows shows pings are sent smoothly in between Linux and Windows
    PC.

    Question: Should I know in which way I can assign IP to my windows PC
    automatically in Windows or Linux? So ping won't fail on Linux.

    Answer: ?

    Thanks,


  2. Re: What's wrong with ARP? DHCP?

    Zieger wrote:
    > HI ALL,
    >
    > I have a home network composed of a Windows XP SP2 PC, a Fedora 7
    > Linux PC and a MFC-8660DN network printer. A linksys switch is working
    > as a hub for my AT&T DSL modem and my home network. And there is a
    > "dhcpserver.exe" running as SYSTEM process on the Windows PC; My
    > "dhclient" task is running on the Linux PC.
    >
    > At the beginning I downloaded a free dhcp server and assigned an IP
    > address to MFC printer (since I didn't know how to configure the
    > Windows dhcp service), After I saw printer got the IP address then I
    > removed it and the dynamic IP address mysteriously stayed in the
    > printer until now (I don't know why it doesn't expire, I didn't set it
    > as permanent).


    Well, you will have to reconfigure your printer to have a fixed IP
    address (if that is what you need it to have).

    >
    > Problem: Now I found the Windows PC can ping the Linux PC correctly
    > ("ping" from windows) but Linux can't get the ping reply("ping" from
    > Linux). Then I tried "arping" from Linux PC and eventually I got the
    > ping reply.
    >
    > I have added Windows PC's IP and MAC with "arp -s" on my Linux PC
    > MANUALLY every time when I start Linux. I know it stays in the ARP
    > cache only. when I use "arp -a" to show all IP links in Linux, I show
    > two other IP addresses assigned automatically for my switch and my
    > printer, but not for my Window PC(which is MANUALLY added in).


    If you have to run arp by hand, then there is something wrong with your
    network!

    You need to have one and only one DHCP server on your network; otherwise
    you will have IP addressing problems.

    >
    > I have left my Linux firewall open for all the traffic. And Ethereal
    > on Windows shows pings are sent smoothly in between Linux and Windows
    > PC.
    >
    > Question: Should I know in which way I can assign IP to my windows PC
    > automatically in Windows or Linux? So ping won't fail on Linux.
    >
    > Answer: ?
    >
    > Thanks,
    >


    Are you running some kind of firewall on your Windows PC? If so, switch
    it off.

    Robert

  3. Re: What's wrong with ARP? DHCP?

    Zieger wrote:
    > I have a home network composed of a Windows XP SP2 PC, a Fedora 7
    > Linux PC and a MFC-8660DN network printer.


    For a small home network, I would just assign static IP addresses to each of
    the devices.

    Mark.

    --
    Mark Hobley
    393 Quinton Road West
    QUINTON
    Birmingham
    B32 1QE

    Email: markhobley at hotpop dot donottypethisbit com

    http://markhobley.yi.org/


  4. Re: What's wrong with ARP? DHCP?

    Thanks Robert,

    I have to say the IP address assigned to Printer is fixed now (without
    DHCP it sticks there until now).

    My biggest concern is why "arping" works but "ping" doesn't work in
    linux?

    -Zieger


  5. Re: What's wrong with ARP? DHCP?

    Mark,

    Why I use DHCP instead of fixed IP is because the network printer runs
    a DHCP client and that's the only way to assign a IP address to it. I
    think.

    -Zieger


  6. Re: What's wrong with ARP? DHCP?


    > My biggest concern is why "arping" works but "ping" doesn't work in
    > linux?

    -Were you able to ping the Windows pc from Linux when you configured
    the Windows pc mac manually on Linux?
    -From my experience I found some Windows pcs don't respond to ping and
    I didn't check why because I found those pcs can work fine inside the
    lan and can reach the Internet, May there is error with afirewall
    installed on Windows and prevent the echo-reply to get out.
    -If ping doesn't work with you some times try Nmap for example to see
    if there any wrongs may you have arp poisoning because of avirus for
    example or some thing else, Because Nmap can ping without ICMP
    actually if you configured it this way and it doesn't get affected
    with arp poisoning anyway and I am sure, To scan apc using Nmap
    without ICMP issue some thing like this,
    nmap -P0 192.168.1.1


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