[Xen-users] Xen Newbie queries

["Sanjay Arora" <sanjay.k.arora@xxxxxxxxx>]

Hello List

Newbie Xen Lurker surfacing for some queries ;-)

I  have a small network with an IPtables firewall with a DMZ and a
Lan Server subnets. There are four servers on Lan & one on the DMZ.

DMZ uses centos 4.2, PIII 550 MHz, 256 MB RAM, no X/GUI, is connected
to a 512 kbps adsl broadband & provides name based apache, mail
server based on qmailtoaster.com, djbdns server, yum for upgrading,
php, perl, mysql & postgresql etc. The DMZ server is having a
private ip address and services are port-forwarded/natted from the main
iptables firewall. It has a single 40 GB HDD using LVM2.

What I want to do is to virtualise each of the services into a seperate
Xen OS instance, with iptables firewalling of its own. Two outcomes are
wanted...1. in case of a compromise of a server through any of the
services, the penetration is limited to that instance of the OS/Service
and 2. I want to put another server on the same subnet in the DMZ and
want to implement an expeditious failover using rsync (not
instantaneous...as I don't think I have  the either the budget or
the expertise to do that...or maybe I am just plain scared to attempt
it).

Later, I want to do the same to services on the LAN.

My questions are:

1. Is Xen virtualization good from the point of security, if I do not
expose any services except for ssh and that too from the internal
network, on the host OS. The guest OS will again be firewalled and will
expose only one service which it is providing, in addition to ssh for
management. In some cases apache may be needed for management, in that
case the apache access will be restricted from one or two management
computers. What are the issues I need to study? Various Pros & Cons?

2. If I get Xen hosting from a hosting provider on a fast network, can
I simply migrate my guestOS (domU...I think you guys call it?) to
them...this can relieve me of management every time I implement
changes/upgrades? Any issues in this?

3. Is Xen production ready? From various Xen Hostings now available, it
seems so...my needs are secure small biz intranet/extranet/mail server
& database usage.

4. What are pen-tester's views of Xen? Tried to search but could not
find much in first few minutes. Maybe Xen is too new or I need to
search better & I intend doing so.

5. My readings conflict about one issue...Xen Host kernel needs to be
patched. What about the guest kernel. One post I read suggested it need
not be patched because of some code borrowed from qemu and improved
upon thereafter...some seem to say guest kernel needs to be patched.

6. I plan on exclusively using Centos...both as a host OS & a guest
OS, but I don't want to go in for custom kernal compilation, every time
Xen updates or CentOS kernel updates. Any packaged rpms available
anywhere? that I can simply use with yum from my local yum repository?

Any other issues I need to look into, given my above use-case
scenario?  Budget: Shoe String/ Expertise: Medium..can compile
softwares if instructions are there but no programming/patch creation
capability. Understand technical issues and administer my own linuses
though am a business person.

Please help...criticism, advise, warnings from pros & oracles wanted/welcome ;-)

With best regards.
Sanjay.



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