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baslinux - [BL] BL2 bare.i as gateway to internet, was Re: NFS on BL3

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  • From: sindi keesan <keesan AT sdf.lonestar.org>
  • To: baslinux AT lists.ibiblio.org
  • Subject: [BL] BL2 bare.i as gateway to internet, was Re: NFS on BL3
  • Date: Thu, 7 Dec 2006 16:32:02 +0000 (UTC)


On Thu, 7 Dec 2006, sindi keesan wrote:

---------------------------------------------
ipchains -P forward DENY
ipchains -A forward -s 192.168.1.0/24 -j MASQ
---------------------------------------------

You will also probably need to set IP forwarding:
----------------------------------------
echo "1" > /proc/sys/net/ipv4/ip_forward
----------------------------------------

Don't need " " - ipchains told me to type the above line when I forgot to.

Computer on left (BL3 with standard kernel, probably P1)
insmod 3c59x, ifconfig eth0 192.168.1.1, route add default gw 192.168.1.2

Computer on right (dialed in now) (BL3 with 'big' kernel)
insmod 3c59x, ifconfig eth0 192.168.1.2, ipchains as above
echo 1 as above

What next? The BL sshd thread petered out, someone was told to compile
their own, and I would need a password package for BL3 (not for BL2).

I found /bin/telnetd symlinked to the BL3 busybox but if I type telnetd
it lists busybox functions and it is not included.

It is in my busybox 1.1.10 package and in 1.0.1 compiled by another list
member (might be glibc version). No useful help on this. I used kill to
unload it. With the ipchains firewall is telnetd safe to run? (I can try
first offline). How would I use it? I recall it was complicated via
serial nullmodem cable.

If I try to telnet to 192.168.1.2 after running telnetd there:
Connection closed by foreign host. This is BL3 without a login package.
I will try BL2.

Sindi

Tried BL2 with bare.i kernel offline first.

insmod 3c59x (ethernet) and ifconfig eth0 192.168.1.1 (computer on left) and 192.168.1.2 (computer on right = gateway, dialup connection via it)

busybox 1.1.0 telnetd on the gateway computer
On the other computer, telnet 192.168.1.2, logged in without asking for a password (which means I should not be running this telnetd online)
and I could run CLI programs on the gateway computer.

(Please remind me again how to run X programs this way).

On the gateway computer I typed the ipchains lines (three of them including echo) to set up a firewall. On the other computer I typed
route add default gw 192.168.1.2 so I could use the gateway computer to go on the internet. (Neither was needed to telnet between my computers).

I noted the process number of telnetd (48), and dialed in with the gateway computer. While still telnetted with busybox telnet, I could ping www.grex.org with the gateway computer and also with the other computer, which means both computers were online (via a telnetd that requires no password). My securetty allows root to login via tth1-4, ttyp0-4, ttyS)-3 ad pts/0 and pts/1. I may have edited it. Should I change this so root cannot log in via ttypN or is the firewall enough protection?


I typed kill 48 right after testing ping. How would I know if someone tried to access my gateway via telnet in this 10 seconds when telnetd was still running after it connected to the internet?

Last time I tried this (with a serial telnet connection) I was not vandalized, using some other telnetd and no firewall.

If I use sshd do I need to ssh to the gateway as user rather than root?
Or is this firewall sufficient?




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