Re: failing to share internet access between two PCs installed with Debian 3.1

From: Dominik Margraf (dominik.margraf_at_gmail.com)
Date: 06/11/05

  • Next message: Kevin Mark: "Re: AFS/OpenAFS" 
    Date: Sat, 11 Jun 2005 21:32:29 +1200
To: "Roberto C. Sanchez" <roberto@familiasanchez.net>, debian-user@lists.debian.org

    On 6/11/05, Roberto C. Sanchez <roberto@familiasanchez.net> wrote:
    > On Sat, Jun 11, 2005 at 08:25:14PM +1200, Dominik Margraf wrote:
    > >
    > > I also installed ipmasq on computer A. Computer A was able to access
    > > the internet. Both Computer A and B could also ping each other
    > > successfully and computer B was also able to share internet from
    > > computer A
    > >
    > What is the output of '/sbin/route -n' from each computer?

    for Computer A (the one connected to the ADSL modem):

    abc@debian1:~$ /sbin/route -n
    Kernel IP routing table
    Destination Gateway Genmask Flags Metric Ref Use Iface
    192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
    10.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth1
    0.0.0.0 10.1.1.1 0.0.0.0 UG 0 0 0 eth1
    abc@debian1:~$

    (note: eth1 is the port connected to the ADSL modem and eth0 is the
    port connected to Computer B via a crossover cable)

    for Computer B:
    abc@debian2:~$ /sbin/route -n
    Kernel IP routing table
    Destination Gateway Genmask Flags Metric Ref Use Iface
    192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
    0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
    abc@debian2:~$

    >
    > > However after I reinstalled Computer A with the newly released debian
    > > 3.1r0a (with exactly the same settings described above) with ipmasq,
    > Uh. Why did you reinstall?
    >

    Because I would like to reallocate the disc space and set up a new
    partition for storing my DVD files.

    > > computer B could not obtain internet access any more despite computer
    > > A still had internet access and computer B was also able to share CUPS
    > > and NFS services from computer A successfully. Also, computer B was
    > > able to ping computer A and vice versa.
    > >
    > > So what could go wrong here? Is it because some problems with the
    > > firewall and/or ipmasq? How could I fix this problem?
    > What firewall program/configuration are you using? What is the output
    > if 'iptables -nL' ?
    >
    > -Roberto

    I did not intentionally install firewall program for both computer or
    tweak the firewall configurations. I just installed the ipmasq
    package, which allows NAT by recomputing the firewall rules. However
    there are the printouts for "iptablees -nL" of both computers:

    Computer A:

    debian1:/home/abc# iptables -nL
    Chain INPUT (policy DROP)
    target prot opt source destination
    ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
    LOG all -- 127.0.0.0/8 0.0.0.0/0 LOG flags
    0 level 4
    DROP all -- 127.0.0.0/8 0.0.0.0/0
    ACCEPT all -- 0.0.0.0/0 255.255.255.255
    ACCEPT all -- 192.168.0.0/24 0.0.0.0/0
    ACCEPT !tcp -- 0.0.0.0/0 224.0.0.0/4
    LOG all -- 192.168.0.0/24 0.0.0.0/0 LOG flags
    0 level 4
    DROP all -- 192.168.0.0/24 0.0.0.0/0
    ACCEPT all -- 0.0.0.0/0 255.255.255.255
    ACCEPT all -- 0.0.0.0/0 10.1.1.5
    ACCEPT all -- 0.0.0.0/0 10.255.255.255
    LOG all -- 0.0.0.0/0 0.0.0.0/0 LOG flags
    0 level 4
    DROP all -- 0.0.0.0/0 0.0.0.0/0

    Chain FORWARD (policy DROP)
    target prot opt source destination
    ACCEPT all -- 192.168.0.0/24 0.0.0.0/0
    ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state
    RELATED,ESTAB LISHED
    LOG all -- 0.0.0.0/0 192.168.0.0/24 LOG flags
    0 level 4
    DROP all -- 0.0.0.0/0 192.168.0.0/24
    LOG all -- 0.0.0.0/0 0.0.0.0/0 LOG flags
    0 level 4
    DROP all -- 0.0.0.0/0 0.0.0.0/0

    Chain OUTPUT (policy DROP)
    target prot opt source destination
    ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
    ACCEPT all -- 0.0.0.0/0 255.255.255.255
    ACCEPT all -- 0.0.0.0/0 192.168.0.0/24
    ACCEPT !tcp -- 0.0.0.0/0 224.0.0.0/4
    LOG all -- 0.0.0.0/0 192.168.0.0/24 LOG flags
    0 level 4
    DROP all -- 0.0.0.0/0 192.168.0.0/24
    ACCEPT all -- 0.0.0.0/0 255.255.255.255
    ACCEPT all -- 10.1.1.5 0.0.0.0/0
    ACCEPT all -- 10.255.255.255 0.0.0.0/0
    LOG all -- 0.0.0.0/0 0.0.0.0/0 LOG flags
    0 level 4
    DROP all -- 0.0.0.0/0 0.0.0.0/0
    debian1:/home/abc#

    Computer B:

    debian2:/home/abc# iptables -nL
    Chain INPUT (policy ACCEPT)
    target prot opt source destination

    Chain FORWARD (policy ACCEPT)
    target prot opt source destination

    Chain OUTPUT (policy ACCEPT)
    target prot opt source destination
    debian2:/home/abc#

    Thank you very much for your help and I would be grateful if you could
    find the culprit!

    Dominik

  • Next message: Kevin Mark: "Re: AFS/OpenAFS"

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