RE: Remote Access (Again)

On Wed, 4 Dec 2002, Justin Haase wrote:
>
> So if your iSeries is on the internet (port 23 or any port for that matter)
> then the sniffer could sniff it.  Internal network with no direct internet
> access, no.  Access to internet, fair game.
>

It doesn't matter if your iSeries is directly connected to the internet,
or if it goes through a few routers first... as long as the packets get
there, they can be sniffed.

>
> Turning ICMP off is the first step in effective security (no ping
> responses).
>

Turning off ICMP is a really bad idea.   ICMP is used for many important
functions in TCP/IP.  It's the error reporting protocol of the internet,
it notifies you when connections to a server can't be made because the
server is not listening, or the routes aren't available, or hosts are
unavailable, or your packets have exceeded their TTLs.

Without it, the TCP/IP protocol cannot work as it was designed to.

If you want to block pings, then use a firewall that's smart enough
to block pings without blocking other ICMP functions.

I don't understand why you think ICMP is a security risk.    All it can do
is a 'Denial Of Service' attack by flooding your network with traffic,
so that important tasks take longer.   Rather than blocking it, you should
simply LIMIT it, so that only X packets can travel through a firewall in
a given amount of time.   That prevents the DOS without breaking the
functionality that ICMP provides.