2002 09 26

                    LINUX NEWS
          September 26, 2002 - Issue #100


1) Sean’s Notes

2) Linux News

    Slapper Continues to Spread
    OEone HomeBase DESKTOP
    SuSE eMail Server: Best of Show?
    PostNuke Developer's Site Launched

3) Linux Resources

    Poke The Penguin, But Not Too Much!
    Syncing a USB PDA to Linux
    Instant Messaging Clients Compared
    Red Hat: Slapper Help
    Logical Volume Management

4) App o’ the Week

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1) Sean's Notes

I might have mentioned it before, but most of my day to day work
is as a network engineer, working on switches, routers, and
firewalls. I've always been a strong advocate of using Linux
boxes as firewalls, but have you ever thought of using them as
a router?

As bandwidth demands increase, providers are moving toward metro
Ethernet access. Rather than point to point T1's, you can have
10Mbit over Ethernet. The hardware to do the serial T1 has
existed on the PC for a while, but most prefer to buy a
dedicated router rather than mess with the Voodoo that is leased
lines and Frame Relay.

So a Linux box can route packets, big deal! In a large network,
dynamic routing is used to keep routes straight, and to provide
redundant paths. Unix has always supported basic routing
protocols like RIP (Routing Information Protocol), but more
advanced protocols like OSPF and BGP are out of reach. Those who
have played on routers will also know the flexibility that goes
on top of that, such as redistribution between protocols and
various filters.

So, a while back, a couple of guys got together and decided to
add some serious routing protocols to Linux. The project is
called Zebra, and is located at http://www.zebra.org. The
interface is, for the most part, a clone of the Cisco IOS,
though there are some enhancements that will either make you
weep for joy, or with frustration.

I pulled down a rpm of Zebra 0.93a from RPMfind.net, upgrading
the version that came with Red Hat. Once installed, you can fire
up the zebra daemon (/etc/rc.d/init.d/zebra start). To access
the router, you either run "vtysh", or telnet to port 2601.

Here's where the quirkiness of zebra kicks in. Each routing
process (zebra, bgpd, ospfd, etc) listens on a different port.
So, to configure Zebra itself, you telnet to 2601. To configure
bgp, you use 2605. Each configuration is separate from each
other. vtysh shows it all, but you can't save your changes from
within it.

That aside, people familiar with the Cisco IOS will be right at
home. Here's the routing table from zebra:

<div class="highlight"><pre><code class="bash">&gt; show ip route
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF,  B - BGP, &gt; - selected route, * - FIB route

K&gt;* via, eth0
C&gt;* is directly connected, eth1
C&gt;* is directly connected, lo
B&gt;* <span class="o">[</span>20/0<span class="o">]</span> via, eth1, 00:05:07
B <span class="o">[</span>20/0<span class="o">]</span> via, eth1, 00:05:07
K&gt;* via, eth1
C&gt;* is directly connected, eth0
K&gt;* via, eth1

With Zebra, any route learned by a routing protocol is propagated
to the kernel. So, from the <span class="nb">command </span>line, my routing table looks

<span class="nv">$ </span>netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Iface   eth1    	eth1   eth1   eth0   eth1   vmnet8       eth1       lo         eth0

The difference is that here, you can't see where you learned
the route from. However the fact remains, your box can interact
with other routers.

Those looking to augment their network test labs, or gain some
experience on Cisco devices without owning any, will also find
Zebra to be useful. The command syntax is almost directly ripped
from IOS, except that addresses are generally entered x.x.x.x/y
instead of x.x.x.x y.y.y.y. Subtle difference, but quicker for
those that think in CIDR.

Unfortunately Zebra's documentation is sparse, so you should be
familiar with routing protocols in general before starting in.

Here's an interesting link showing Zebra as part of a global
load balancing network. An interesting project, if you ask me:


The functionality of Linux as a router is coming close to the
appliance-based routers such as those that Cisco sells. Quality
of Service, routing protocols, and filtering are all available.
Depending on your needs, such as simple routing between Ethernet
interfaces, the cost of a Linux box might be a lot cheaper than
a Cisco router. Mind you, the performance peaks might not be as
high, but if we're only talking about 10Mbit interfaces, it's
not an issue.

Long live the Penguin,


2) Linux News

Slapper Continues to Spread

The Slapper worm has been making its rounds by exploiting the
SSL flaws in Apache. It's on its third variant already, and
seems to be causing a great deal of havoc.


OEone HomeBase DESKTOP

In an effort similar to Ximian's, OEone has come up with a Linux
desktop. They're trying to bundle it with a sort of Internet
backup service, prices seem fairly reasonable. Just like Ximian,
the install can be done over the Internet, so it might be worth
taking a look. Here's a review from Linuxorbit.


SuSE eMail Server: Best of Show?

"Pop quiz: what messaging server has group calendaring,
including free/busy notifications, group contacts, POP3 and
IMAP, built-in encryption, Web mail, low system requirements,
high scalability, reasonable cost, and non-restrictive
licensing? Answer: SuSE Linux eMail Server 3.1."


PostNuke Developer's Site Launched

PostNuke is a more serious offshoot of PHPNuke, a Content
Management System written in PHP. They've just announced a
developer's site devoted to extending this fantastic piece of


3) Linux Resources

Poke The Penguin, But Not Too Much!

Here's a fun little Flash program that lets you poke a Penguin.
Do you think he'll put up with it though? Try and see what
happens when you make a penguin angry!


Syncing a USB PDA to Linux

Follow a sysadmin as he sets up his Visor to back up to his
Linux box over USB!


Instant Messaging Clients Compared

"Somehow, some way, people who are new to Linux have gotten the
idea that Linux has limited IM choices. Since the Unix family
was the first to have popular IM clients (with "talk" leading
the way), that's more than a little silly. It is true that if
you want the latest AOL Instant Messenger (AIM) features or MSN
Messenger you're out of luck, but there are many other clients
to choose from, and some will let you talk to your buddies
whether they're on AIM, MSN, or even Yahoo!."


Red Hat: Slapper Help
Here's a document from Red Hat that specifically talks about
the Slapper worm. Turns out the fix has been available since
the end of July (up2date took care of my web server).


Logical Volume Management

"With LVM, you can combine partitions or drives into one large
storage pool, called a volume group, and from there create
logical volumes for filesystems." LVM is cool stuff, allowing
on-the-fly disk management.


4) App o' the Week

PHPMyAdmin is a great web-based administration tool for MySQL
databases. It's currently popular with hosting sites, to make it
easier for users to create tables and manage their database.


(C) 2002 BrainBuzz.com, Inc. All Rights Reserved.

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