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Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
Synopsis
Audience: Solaris 10 (and later) System Managers
This note is a quick "jumpstart" for Solaris System Managers at the University of Waterloo who
want to use IP filters (ie. local host-based firewalls) on Solaris 10 (and we hope later versions of
Solaris). The intention is to show you how to configure a baseline that should be adequate for
most and give some hints on how you can alter that baseline to meet additional requirements you
might have.
The baseline we develop is suitable for a "client-only" system managed by xhier that offers very
few services beyond remote access via ssh. Building exceptions onto that baseline for web
servers, database servers, etc. is not terribly difficult and hopefully we’ve given enough help to
point you in the right direction.
Limitations: we will not discuss the configuration required for a system acting as a router or as a
NAT server. Both are beyond the scope of this document and, in any case, we discourage the use
of any Unix systems for those applications. Our focus is on ingress rules (to protect the system
from attack) -- we make no effort on egress rules.
Beware: Solaris IP Filters on Solaris 10 are radically different from and replace the SunScreen
firewall which was available on earlier versions of Solaris. Solaris IP Filters are derived from
open source IP Filter software and will be familiar to those who have used "ipfilters" on freeBSD
and other systems.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
Issue
The fundamental problem we need to deal with is this -- the Internet is a very nasty place and
systems out of the box expose far too many services. Our Attacks & Attackers data shows that
our site is always under attack. Our Vulnerability site shows the issues under attack.
So how can we protect ourselves from attack? We can harden systems to eliminate services (see
for example our paper on Security Review: Solaris Network Hardening) but there will be required
services where you should control access. For example, while it’s always prudent to eliminate a
service like "rlogin" in favour of "ssh" access there are other services which will be required. The
classic example at our site is the rsh requirement for xhier management. You need to offer the
rsh service but you don’t need to offer it to the world -- you only need to expose it to your xhier
server.
Host-based firewalls are a technology where on the machine itself you configure access controls
to services offered. This makes it possible to protect your system from remote attacks (as a
network firewall would) but also to protect your system from local attacks -- a network firewall
cannot protect a system from malicious peers on the same network segment. We’ve used the
tcpwrapper to limit access to services managed by inetd but that only works for services
managed by inetd and then only tcp services (the tcpwrapper does not handle udp services very
well and can do nothing for icmp serivces). The tcpwrapper is an application layer firewall with
some serious limitations.
IPfilters are a host-based firewall technology layered within the kernel of the operating system.
With IPfilters you can limit access to any and all network services. The application layers will not
get anything unless the IPfilters allows it. That makes IPfilters a powerful tool for protecting
systems.
Beware: while IPfilters are an important tool for securing systems they cannot protect you from
all problems. You can limit access to ssh with IPfilters -- you can’t stop users from picking dumb
passwords that are easily guessed!
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
How to... Step 1
Before going anywhere you need to have the right packages installed and the right services ready.
By default Solaris 10 arrives with IPfilters -- but it is not enabled and the provided configuration
does no filtering. The package you require on Solaris 10 are SUNWipfr and SUNWipfu:
[1:20pm sun510]# pkginfo | grep "IP Filter"
system SUNWipfr IP Filter utilities, (Root)
system SUNWipfu IP Filter utilities, (Usr)
If you don’t have these packages installed you’ll need to install them off the Solaris 10
distribution CD’s. Assuming you have the packages installed you should have a couple of
services available to you:
[1:24pm sun510]# svcs network/pfil
STATE STIME FMRI
online Jul_25 svc:/network/pfil:default
[1:24pm sun510]# svcs network/ipfilter
STATE STIME FMRI
disabled Jul_25 svc:/network/ipfilter:default
The packages come with configuration files here:
[1:24pm sun510]# ls /etc/ipf/
ipf.conf pfil.ap
The ipf.conf file is the filter rules that will be applied -- the default configuration has no rules.
The pfil.ap lists network interfaces where you might want packet filtering.
Tasks to Perform:
The first step in configuring IP filters is to configure the package to do packet filtering on your
network interfaces and configure the associated services so they’re enabled and running.
Edit /etc/pfil/pfil.ap and uncomment the name of the network interface (on many older
systems the "hme" interface was common). Newer SunFire systems use a mix of "qfe"
(sunfire V210, 240), "ce" (sunfire 440), "eri" (Sunblades), and other device names. But for
this example let’s assume a "hme" device:
[11:19am sun510]# cat /etc/ipf/pfil.ap
# IP Filter pfil autopush setup
#
# See autopush(1M) manpage for more information.
#
# Format of the entries in this file is:
#
#major minor lastminor modules
#le -1 0 pfil
#qe -1 0 pfil
hme -1 0 pfil
#qfe -1 0 pfil
#eri -1 0 pfil
#ce -1 0 pfil
#bge -1 0 pfil
#be -1 0 pfil
#vge -1 0 pfil
#ge -1 0 pfil
#nf -1 0 pfil
#fa -1 0 pfil
#ci -1 0 pfil
#el -1 0 pfil
#ipdptp -1 0 pfil
#lane -1 0 pfil
#dmfe -1 0 pfil
Note: to determine your network interface run the command "ifconfig -a".
Make sure both required services are enabled and online:
[11:19am sun510]# svcadm enable network/pfil
[11:19am sun510]# svcs network/pfil
STATE STIME FMRI
online Aug_22 svc:/network/pfil:default
[11:19am sun510]# svcadm enable network/ipfilter
[11:19am sun510]# svcs network/ipfilter
STATE STIME FMRI
online 11:24:04 svc:/network/ipfilter:default
Now reboot your system
[11:19am sun510] reboot
When the system reboots you will have a running system with a default rule set that filters
nothing.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
How to... Step 2
The second step once you have IP filters running is to configure a rule set for packet filtering and
put that rule set into production. The vendor provided rule set has nothing in it although you are
filtering nothing is blocked:
[11:46am sun510]# more /etc/ipf/ipf.conf
#
# ipf.conf
#
# IP Filter rules to be loaded during startup
#
# See ipf(4) manpage for more information on
# IP Filter rules syntax.
A basic configuration, and a very good baseline to start from, is to configure your machine so that
it can connect to anything it wants but protect it so that nobody can connect to any services on it.
This is what we like to call a "client-only" configuration (compare with the Windows XP
Firewall). A short rule set that would do that:
[11:46am sun510]# more /etc/ipf/ipf.conf
# Example A: Simple Client-Only configuration
# Allow any outbound traffic from this computer (and the response)
pass out quick all keep state
# Block anything inbound that I did not originate
block in all
Edit a new configuration file as above (or download Example A). Since the running system is
using the configuration file found at boot time your edits don’t have any immediate affect. To get
the running system to use the new configuration file run the command:
[11:46am sun510]# ipf -Fa -f /etc/ipf/ipf.conf
If you’ve made an errors you will get some gripes and it won’t load the configuration.
Beware: it should be clear that loading the configuration given cannot be done from an
"ssh" session over the network. You must do this from the system console (or include rules
in the configuration to allow your network connection).
What you should know....
Rules are applied as IP packets are moved from a physical device through the Solaris kernel to an
application (that’s the in keyword) and as IP packets are moved from an application through the
Solaris kernel to the physical device (that’s the out keyword). The IP filter can either pass or
block the traffic. Assuming that the system is not a router or a NAT server -- anything coming
"in" is for the system, anything going "out" is from the system.
The two rules in this quick configuration work this way.
1. Anything outbound should be permitted, don’t bother applying any more rules (that’s the
quick keyword), and keep a state marker so that anything returned on that same connection
is allowed.
2. The final rule blocks everything else.
That is a good base configuration for a machine that offers no services. If nobody can connect to
any services on your system then all services are well protected.
The impact on the user experience is minimal. The local X11 environment will work fine, you
can browse the web and can connect to any systems and services you want around the net. Note
that applications on other systems cannot connect to your X11 display (see the Beware notes and
learn about "ssh" tunnelling).
In the next section we’ll extend this configuration by adding some optimization tricks and
configuring some exceptions for services we might offer.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
How to... Step 3
In this section we’ll extend the base configuration by adding some optimization tricks and
configuring some exceptions for services we need to offer. We recommend you add exceptions as
you need them.
For testing and development it will be important to log events so you can see what’s going
on. We recommend you replace the final rule with:
# Example B: Simple Client-Only configuration
# Allow any outbound traffic from this computer (and the response)
pass out quick all keep state
# Block and log anything inbound that I did not originate
block in log all
Load this minor change (or download Example B) and you can now monitor the filter as it’s
applied in real time:
[3:55pm sun510]# ipf -Fa -f /etc/ipf/ipf.conf
[3:56pm sun510]# ipmon -a
31/08/2005 15:56:33.021348 8x hme0 @0:8 b 129.97.109.1,520 -> 129.97.109.255,520 PR udp len 20 532 IN
31/08/2005 15:56:41.909647 hme0 @0:8 b 129.97.109.75,138 -> 129.97.109.255,138 PR udp len 20 229 IN
.... etc.
You may see an IP filter configuration where the first rules permit traffic on the loopback
interface:
# Allow loopback traffic
pass in quick on lo0 all
pass out quick on lo0 all
The loopback interface (it has IP number [127.0.0.1]) will only support IP traffic to and from
the machine itself. It enables IP traffic independent of any real networks. Any traffic arriving
to/from the loopback interface must have originated on the machine itself.
My rule where I allow outbound traffic on any interface and keep the state is sufficient. It
does not hurt to add this rule and it may well be required it you implement any outbound
filters. If you download Example C you’ll have a version with that addition.
You will encounter rules that block packets arriving from non-routeable private networks:
# block from non-routable addresses
block in quick from 10.0.0.0/8
block in quick from 172.16.0.0/12
block in quick from 192.168.0.0/16
One shouldn’t normally see any packets from these networks. At our site there is some
routing of private networks but most systems should never see these and should block them.
If your system offers any services then you probably should block these. For a client only
configuration (where all traffic is the result of something you initiate) this problably isn’t
required. Example D includes this addition.
Many people access Unix systems using ssh services for system management. To expose
that service to the campus (or to the world) try a rule like:
# Allow ssh inbound
#pass in quick proto tcp from any to any port = 22 keep state
pass in quick proto tcp from 129.97.0.0/16 to any port = 22 keep state
The exposed rule limits the exposure to just our campus -- we limit off campus access to
only a few servers. Critical servers expose the service to only those managers who need
access. Example E includes this addition.
If your system is a web server that you want to expose to the world add rules like this:
# Allow http and https inbound
pass in quick proto tcp from any to any port = 80 keep state
pass in quick proto tcp from any to any port = 443 keep state
Port 80 is "http" while port 443 is used for "https" (it’s not good practice to offer web
services on other port numbers). Example F includes this addition.
If your system is a mail server you’ll want to expose a collection of services (but not
necessarily all of these):
# Allow inbound mail services (smtp, smtps, submission)
pass in quick proto tcp from any to any port = 25 keep state
pass in quick proto tcp from any to any port = 465 keep state
# pass in quick proto tcp from any to any port = 587 keep state
A mail server accepts mail on port 25, port 465 is an SSL encrypted version of the same, and
port 587 is another version of the same but this time the SSL is optional.
# Allow inbound mail services (imap and imaps)
# pass in quick proto tcp from any to any port = 143 keep state
pass in quick proto tcp from any to any port = 993 keep state
"imap" mail services are for clients to read their mail (from applications like Outlook
Express). These days most client applications can handle the SSL encrypted version at port
993 -- I recommend you disable the clear text version (or at least limit it to on-campus only).
# Allow inbound mail services (pop3 and pop3s)
#pass in quick proto tcp from any to any port = 110 keep state
#pass in quick proto tcp from any to any port = 995 keep state
"Pop3" services are another way for client applications to retrieve their mail from a mail
server. I recommend "imap" over "pop3". If you must offer pop3 services I recommend only
the encrypted version at port 995/tcp (or limit the clear text to on-campus only). Example G
includes these additions.
At UW there are lots of systems that rely on xhier for package management. This requires
that a trusted system have rsh access to your server. If your system is an xhier client then
you’ll need a rule like this:
# Allow rsh from arch master
pass in quick proto tcp from 129.97.128.175 to any port = 514 keep state
The rsh service is a "tcp" service on port "514". This rule allows inbound traffic from a
particular system (that should be your "xhier arch master") to access that port. Example H
includes this additions -- note that you must edit the configuration accordingly to list the
right client.
At UW we have a system called "dominic" at [129.97.128.230] that we use to scan the
campus network for problems. You might wish to allow dominic probe your system (it’s not
required), if you do add a rule like this:
# Dominic security scanning of me and others
pass in quick from 129.97.128.230/32 keep state
Example I includes this addition. If you expose any services we can test them for problems
which might arise. If you have services you haven’t eliminiated (but have blocked with the
firewall) you may get advisories about services you should disable (even though nobody can
get to them).
We rely on backup/recover services based on EMC Legato, you need to expose some
services to your backup/recover server. These rules are sufficient to expose the services
required to a machine "hoover" at [129.97.128.9]:
# Allow Legato from hoover
pass in quick proto tcp from 129.97.128.9 to any port = 7937 keep state
# pass in quick proto tcp from 129.97.128.9 to any port = 7938 keep state
# pass in quick proto tcp from 129.97.128.9 to any port = 7939 keep state
Example J includes this addition. Note that the configuration assumes a particular Legato
server that will contact you for backups. If you’re using a different server then you should
edit accordingly. Note: I believe only port 7937 is required -- check your system to
determine where you offer the service.
While Legato is an RPC service the Portmapper at port 111 does not need to be exposed.
For doing network diagnostics it’s often nice to have all systems respond to a "ping". A good
rule to do that, but to limit that to on-campus only testing is:
# Allow pings from campus
pass in quick proto icmp from 129.97.0.0/16 to any icmp-type 8
The "ping" is implemented as an "ICMP message of a certain type (ICMP messages don’t
have port numbers. Example K includes this addition -- some colleagues believe this is an
essential rule.
The "auth" service on port 113/tcp may be queried by several services you use (email
services in particular). We recommend that you don’t run the server and instead answer
quickly that there is no such server. Add a rule like this:
# Block ident with a TCP RST
block return-rst in quick proto tcp to port = 113
If you don’t answer quickly then some applications may be slow to start (they want to
connect to your "auth" service before proceding). Example L includes this addition -- some
colleagues believe this is an essential rule.
Along the same lines as the "auth" configuration. You may encounter a final rule like this:
# Block remainingg TCP RST
block return-rst in quick proto tcp from any to any
This configuration is just a variation on the "auth" rule. The bad thing about this
configuration is that attackers who scan for TCP services will be able to quickly determine
that your system exists.
For more examples of IP Filters see Creating and Editing Solaris IP Filter Configuration Files at
the Sun Documentation Site. Their examples are very useful.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
System Logs
You may have noticed a new application running when you’ve enabled IP filters. There will be a
standing daemon called ipmon:
[11:34am sun510]# ps -ef | grep ipmon
root 21450 1 0 11:24:05 ? 0:00 ipmon -Ds
root 21517 21433 0 11:35:19 pts/3 0:00 grep ipmon
[11:34am sun510]# cd /etc/ipf
[11:34am sun510]# ls
ipf.conf ipmon.pid pfil.ap
[11:35am sun510]# more ipmon.pid
21450
This daemon will be restarted at boot time. It logs information received from the IP filtering
service to the syslog daemon. Some things you need to know:
Events are logged to the local0 facilty. You need to configure /etc/syslog.conf to capture and
log events. On a busy system there will be a lot of events.
Packets that are passed are logged at the "notice" level, those that are blocked are logged at
the "warning" level. But nothing is logged at all unless you use the log keyword in your filter
rules. See for example, Example B (and others) where we log all packets blocked by our
final rule -- very useful when you are trying to debug a problem.
You can run ipmon in real time to see what is currently happening -- it will show events as
they’re happening:
[11:34am sun510]# ipmon -a
19/08/2005 10:56:54.040122 STATE:CLOSE 129.97.128.175,40937 -> 129.97.109.165,23
PR tcp Forward: Pkts in 18 Bytes in 872 Pkts out 0 Bytes out 0 Backward: Pkts i
n 0 Bytes in 0 Pkts out 16 Bytes out 1123
19/08/2005 10:58:00.550294 STATE:NEW 129.97.109.165,32875 -> 129.97.128.10,53 PR
udp
19/08/2005 10:58:00.553235 STATE:NEW 129.97.109.165,32878 -> 129.97.128.100,53 P
R udp
19/08/2005 10:58:02.030894 STATE:NEW 129.97.109.165,32879 -> 129.97.128.10,53 PR
udp
19/08/2005 10:58:02.276093 STATE:NEW 129.97.109.165,32916 -> 129.97.15.123,22 PR
tcp
19/08/2005 10:58:10.537350 STATE:NEW 129.97.128.175,740 -> 129.97.109.165,514 PR
tcp
....etc.
A related task to the system logs is the summary status of the filter:
[5:05pm sun510]# ipfstat
bad packets: in 0 out 0
input packets: blocked 9236 passed 2782 nomatch 0 counted 0 short 0
output packets: blocked 0 passed 2597 nomatch 0 counted 0 short 0
input packets logged: blocked 9112 passed 0
output packets logged: blocked 0 passed 0
packets logged: input 0 output 0
log failures: input 0 output 0
fragment state(in): kept 0 lost 0
fragment state(out): kept 0 lost 0
packet state(in): kept 4 lost 0
packet state(out): kept 127 lost 65
ICMP replies: 0 TCP RSTs sent: 216
Invalid source(in): 0
Result cache hits(in): 5084 (out): 0
IN Pullups succeeded: 0 failed: 0
OUT Pullups succeeded: 0 failed: 0
Fastroute successes: 216 failures: 0
TCP cksum fails(in): 0 (out): 0
IPF Ticks: 31167
Packet log flags set: (0)
none
If you want to see which rules are being applied try
[3:34pm sun510]# ipfstat -h -i
0 pass in quick on lo0 all
53 block in quick from 10.0.0.0/8 to any
3 pass in quick proto tcp from 129.97.0.0/16 to any port = ssh keep state
53 pass in quick proto tcp from 129.97.128.175/32 to any port = shell keep state
0 pass in log quick from 129.97.128.9/32 to any keep state
0 pass in quick proto icmp from 129.97.0.0/16 to any icmp-type echo
38 pass in quick from 129.97.128.230/32 to any keep state
1 block return-rst in quick proto tcp from any to any port = 113
256937 block in log quick all
This output tells me that my rules, see Example C, about the loopback interface aren’t being
applied. That makes me think there’s no filtering at all on that device. Or perhaps the "pass out
quick all keep state" rule is enough -- after all if it’s coming in on that interface it must gone out
on the same loopback interface. The rule about blocking packets from non-routeable networks has
been used several times -- that’s odd.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
Beware
The sample IP filter works well to protect a system. But there are some consequences you might
not be aware of. Some things you may think should work but won’t because of the firewall. Any
application that erects a service is going to be a problem. Some problems are easy enough to find
work arounds.
FTP -- the data channel can be a problem. The traditional FTP client interacts with the FTP
server using two channels -- a command channel at port 21/tcp on the server and a data
channel from port 20/tcp on the server. The client erects a server on an ephemeral port and
the server connects to it from port 20/tcp. This is called "active" mode and it will not work
with the ruleset we presented -- the client cannot start a server on arbitrary ports.
Fortunately the FTP protocol has a "passive" where the data channel is built with the client
connecting to the server and that will work quite well from a firewalled client. Most web
browsers (including Mozilla which comes with Solaris 10) implement passive mode ftp by
default. The ftp command line client has a passive command to set passive mode (you can
also start it in passive mode with "ftp -p").
Many users never access ftp sites, or if they do it’s from a browser, so this should not be a
big issue.
RSH -- the error channel is problematic. The RSH client will offer a services at a low
numbered port for the error channel and the RSH server will connect to that port. The
firewall rules we developed prevent the client from starting a server on arbitrary low number
ports.
If your firewalled system needs to use the "rsh" command then you have to allow all RSH
servers to have access to all low numbered ports (tcp ports less than 1024). This is a nasty
problem for xhier servers who distribute files using the RSH protocol. It makes them very
hard to rigorously firewall.
We encourage users to abandon the clear text RSH in favor of the cryptographically strong
SSH tool set.
X11 -- the X11 server is a problem. For desktop Solaris systems the display device is an X11
server on port 6000/tcp. If you’re in the habit of running X11 applications on various
systems with their display back on your console this won’t work any longer. You can update
the firewall configuration to expose the X11 service to other systems, however, the preferred
strategy is to use SSH and tunneling.
On backroom servers don’t usually have an X11 device so it’s not an issue there. For Solaris
workstations with an X11 display device most applications are run from the same system so
the firewall isn’t an issue. For applications run on other systems the SSH tunnel is an ideal
workaround.
NFS -- the Network File System, for both clients and servers, is awfully hard to firewall.
There are quite a few RPC services related to NFS and not all are located at fixed port
numbers. The command "rpcinfo -p" will tell you where your RPC services are located. I
understand the ports involved are:
The RPC portmapper (see "rpcbind(1M)") offers a service at ports 111/tcp and 111/udp.
Both client and server need to offer this. This is a "locator" service so used to find
services which aren’t at fixed ports.
The server offers "nfsd(1M)" at ports 2049/tcp and 2049/udp. The server needs to offer
this to the client.
The server offers a "mountd(1M)" service but this will be located at an ephemeral port
number -- I understand this will be a number bigger than 32768. You’ll need to
experiment to find the range that works for you but 32768-33000/tcp and
32768-3300/udp ought to be sufficient.
The server might offer a "rquotad(1M)" service (it’s optional for reporting file quotas to
clients) at an ephermal port number in the same range.
Both the server and the client need to offer a "statd(1M)" and a "lockd(1M)" service to
coordinate file locking between clients and the server. Again these are ephemeral port
numbers in the same range,
It should be clear that firewalling an NFS environment will be difficult. Difficult, not
impossible. At our site I do not recommend using Solaris (or any other Unix) systems as NFS
servers. I certainly do not recommnd NFS services on a system that’s allocated to other
purposes. NFS servers should be single purpose systems.
It should it be clear that machines which offer services can use the sample configuration we’ve
provided but will need to have firewall exceptions for the services they offer.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
Summary
Configuring IP filters on Solaris 10 requires that you first:
Edit /etc/ipf/pfil.ap to list your network interface.
Use svcadm to enable "network/pfil" and "network/ipfilter"
Reboot the system to get everything running.
The second step is to configure /etc/ipf/ipf.conf. You should work slowly from a baseline.
The Sample IP Configuration provided includes all of the examples discussed here as well as
some details on services discussed in our Beware section. There’s also sample fragments for key
services we’ve not discussed.
When developing an IP filter take advantage of the System Logs to resolve problems.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
Acknowledgments
Jason Testart of the Computer Science Computing Facility here at the University of Waterloo was
kind enough to give a morning of his time to show me how to configure IP Filters on Solaris 10.
He had the experience with freeBSD and fortunately that ported quickly to the Solaris
environment. I am grateful for his help and patience.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
Using Solaris IP Filters
Information Systems and Technology
University of Waterloo
See Also
Sun has lots of good information at the Sun Documentation. For our initial configuration we
relied on our existing expertise with IP filters and these documents:
Solaris 10 System Administrator Collection
System Administration Guide: IP Services
Part IV IP Security
Chapter 24 Solaris IP Filter (Overview)
Chapter 25 Solaris IP Filter (Tasks)
The important part is Chapter 25. No doubt there are lots of other good pages you can find at the
Sun documentation site and good pages by others at other sites as well.
(by) Reg Quinton, Information Systems and Technology
2005/08/19 - 2008/02/21
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