Bandwidth hit in natd/ipfw on 4.4-RELEASE

Mark Weisman mark at
Fri Apr 2 23:59:58 PST 2004

My first question to help is why do you have any firewall at all? 
Typically means that you have no ports being blocked? I'm hoping this is
just for testing purposes? 
I see in your natd.conf file you have a line for unregistered_only=YES.
This switch is for alteration of outgoing packets based on RFC 1918. I'm
assuming then that you are looking at using natd for outgoing packets
only? In which case in your files you would identify the
natd_interface=dc0 allowing for the unregistered statement to then alter
outgoing packets. I would also suggest if you have any LinkSys routers
between your FBSD box and the Internet, that you examine them, as I have
just recently replaced all my Internet hard routers with CISCO's due to
the LinkSys being unable to hold an MTU setting. Just my two cents.

Res Ipsa Loquitor,
Mark-Nathaniel Weisman
Site Master
Mystic_One Internet Gaming Server
Anchorage, Alaska

-----Original Message-----
From: webmaster at [mailto:webmaster at]

Sent: Thursday, March 25, 2004 6:24 PM
To: freebsd-questions at
Subject: Bandwidth hit in natd/ipfw on 4.4-RELEASE

Hey, I just my got NAT box running 4.4-RELEASE on an old Pentium 90 and 
I'm experiencing a number of problems and I think they're related.. 
there's been a major bandwidth hit in all my web surfing and my ICQ, AOL
and MSN (using both Trillian and Messenger) are dropping connections --
a lot. I don't think a single day's gone by without a connection
dropping or two. As I said before, I've taken a bandwidth hit on my
surfing as well -- to the point where connection attempts are completely
timing out. I've included an abbreviated rc.conf and my natd.conf here..


ifconfig_dc0="inet netmask" inetd_enable="YES"
<snip> gateway_enable=YES natd_enable=YES natd_inteface=rl0
natd_flags="-config /etc/natd.conf" firewall_enable=YES


unregistered_only yes
same_ports yes
log yes
dynamic yes
interface rl0

Did I do anything wrong? Miss anything? Add anything unnecessary? The 
kernel's been recompiled as is appropriate.

Thanks in advance.

Matt Coe, CCNA
Member-At-Large, Dalhousie University CS Society Fall 2003

'Ford! There's an infinite number of monkeys outside who want to talk to
us about this script for Hamlet they've worked out.'
 -- DNA, 'The Hitch Hiker's Guide to the Galaxy', Arthur Philip Dent

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