Re: [SLUG] Bad IP address?

From: Matt Miller (mmiller1@mptotalcare.com)
Date: Mon Aug 26 2002 - 13:36:57 EDT


On Mon, 2002-08-26 at 11:50, Mikes work account wrote:
> One day last week, one of our consultants who logs in via VPN, was unable to
> do so. It seems that the assigned IP address was blocked by the Linux
> server. Others worked just fine. When we omitted that IP address and
> forced the use of another IP address, he was able to access the Linux box
> just fine.

Here are some ideas:
a) tcpd - tcp wrappers?; check hosts.allow and hosts.deny in /etc.
b) Firewall dropping packets according to preset rules? -- iptables,
ipchains, PIX, etc.
c) Routing? -- VPN subnet does not know how to get to the Linux server?
d) A less likely scenario is that the service the VPN client needed to
connect to required a reverse resolution for the ip, and the forced IP
address supplied to the host had an existing PTR record.

> And where can I find out why the server denied access to that
> one address?
>

Logs, logs, logs. Look in /var.
Attempt a reconnect under the same conditions. Run any unreachable
service in debug. Run tcpdump on the appropriate interface filtering for
the assigned VPN ip.

-- 
Matt Miller
Systems Administrator
MP TotalCare
gpg public key id: 
08BC7B06




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