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Welcome to WordPress.com. This is your first post. Edit or delete it and start blogging!
You can get the following features :
– CF-Card Linux Firewall
– Plug and Play
– Web-base configuration
– Fast Boot
– Full Features Stateful Firewall
– Performance depend on Host PC
– Feature Upgradable
Get compact flash compressed image from
http://cid-82e28ccf2b3f821c.skydrive.live.com/self.aspx/Public/128flash-basic.zip
Then unzip image file you will get an image of firewall.
128flash-basic.img
Then you can use windows to write this image to CF card via card reader by use phydiskwrite from m0n0wall to write image to cf card.
http://m0n0.ch/wall/physdiskwrite.php
type this command in dos prompt
physdiskwrite [-u] 128flash-basic.img
after finish put this CF card to CF to IDE adapter
And use IDE cable connect to primary IDE port, then reboot.
after reboot you can login to console and configure as you need or use web browser to http://192.168.1.1 (you must connected lan with this pc) configure to for your network, then this computer become a stateful firewall.
Datasheet
http://www.csntnet.com/data/CF-IPCop-Firewall-th.pdf
http://www.csntnet.com/data/CF-IPCop-Firewall-en.pdf
ScreenShot
http://www.ipcop.org/index.php?module=pnWikka&tag=IPCopScreenshots
A new ASUS compact PC Mini-ITX platform for Digital Home called NOVA Lite with Celeron M 900 Mhz 1GByte DDR2 80Gbyte SATA II and Supper DVD slot in drive. It shipped with Red Flag Desktop 5.0 Linux (Chinese Linux distribution).
Open box content the NOVALite.
Bundled component under the NOVALite.
Top view.
Bottom view.
Front view with Slot in DVD with Eject and Power on touch.
Rear view with 4 USB, DVI, Audio, LAN and DC Power.
Included with DVI to VGA Adapter, user manual, Driver cd (for Windows XP) and DC adapter.
Plug in all connector with keyboard, mouse, monitor, then boot you will see Red flag Linux login prompt. It installed Red flag Linux with X, but don’t have KDE or GNOME. So you type root and enter.
Then you can use command line interface for using Red flag Linux, you can add addition package as you need, but I prefer another distribution.
One thing that I prefer for a new distribution because Red Flag Linux come with NOVALite have older kernel and don’t have ethernet module.
The I use gOS-space 2.9 cd try to boot in safe graphic mode.
It work well with this PC all hardware detected.
It use ATL2 driver module for ethernet interface.
All eth0 ethernet interface and WLAN0 D-Link DL122 usb wireless lan adapter are available for use.
Then just click install and follow up step then you will have a new cool Linux machine.
ถ้าเมืองไทยมีพิพิธภัณฑ์ Internet!! ณ วันนี้ Analog MODEM คงเป็นอีกอุปกรณ์หนี่งที่ถูกจัดแสดงไว้อยู่ด้วย Analog MODEM เป็นอุปกรณ์เสริมที่จำเป็นสำหรับคอมพิวเตอร์ส่วนบุคคลตามบ้านเพื่อเชื่อมต่อ Internet มาค่อนข้างนาน นับตั้งแต่เริ่มมีInternet ขึ้นมา เพราะมีราคาถูกและใช้กับคู่สายโทรศัพท์ที่มีอยู่แล้วเกือบทุกบ้านได้เลยแต่อนิจจังมีเกิดย่อมมีดับนั้นเป็นจริงกับทุกสรรพสิ่ง
รูปที่ 1 Broadband Frequency Band
เทคโนโลยี Internet เป็นเทคโนโลยีที่มีวิวัฒนาการไปอย่างรวดเร็วควบคู่ไปกับเทคโนโลยีของคอมพิวเตอร์ ที่ปัจจุบันมี CPU สำหรับคอมพิวเตอร์ส่วนบุคคลถึง 4 Core ใช้กันแล้ว ความแรงนั้นอาจจะแรงกว่า Server ราคาหลายๆแสนที่มีขายกันอยู่เมื่อ 2-3 ปีที่ผ่านมา
สำหรับเทคโนโลยี Internet ก็แรงไช่เล่นเช่นกัน เทคโนโลยี Broadband เป็นเทคโนโลยีที่กลายเป็นเทคโนโลยีที่เข้าถึงตามบ้านในเขตเมืองแทน ซึ่งเรียกว่า Digital Subscriber Line (xDSL โดย x อาจเป็น V, S, A, H ซึ่งเป็นเทคโนโลยีย่อยของ DSL แต่ที่ใช้ตามบ้านคือ ADSL, Asymmetric Digital Subscriber Line) ซึ่งเทคโนโลยีที่ว่านี้สามารถใช้กับคู่สายโทรศัพท์ที่มีอยู่แล้วเช่นกัน ซึ่งทางผู้ให้บริการเครือข่ายโทรศัพท์ เช่น TOT หรือ TRUE จะมีการ Upgrade ระบบเครือข่ายโทรศัพท์ของตนเอง เพื่อที่จะสามารถใช้ย่านความถี่ (Frequency Band) ที่ว่างอยู่ของคู่สายโทรศัพท์สำหรับการส่งข้อมูล ซึ่งสัญญาณเสียงใช้ย่านความถี่ไม่เกิน 4 kHz ดังนั้นย่านความถี่ที่สูงกว่าย่านความถี่เสียง ( >4 kHz ) จึงถูกนำมาใช้ในการรับส่งข้อมูลของ Internet สำหรับการ Upload และ Download (โดยปกติในทาง Technical Term มักใช้คำว่าUplink/Downlink แต่เพื่อให้เข้าใจได้ง่ายขึ้นจึงใช้ Upload/Download แทน)โดยที่ ADSL การ Upload และ Download จะใช้จำนวนของช่องความถี่ไม่เท่ากัน (จึงใช้คำนำหน้าว่า Asymmetric) ซึ่งปกติ Download จะใช้จำนวนช่องความถี่มากกว่า Upload จึงทำให้ Bandwidth สำหรับการ Download จะสูงกว่า Upload เช่น 256k/128k คือ มี Bandwidth สำหรับ Download เป็น 256 kilo bit ต่อวินาที แต่ Upload มี Bandwidth เป็น 128 kilo bit ต่อวินาที ซึ่งลักษณะการแบ่งย่านความถี่ของคู่สายโทรศัพท์เป็นไปในลักษณะตามรูปที่ 1 ซึ่งแบ่งออกเป็น 3 ย่านความถี่ (Frequency Band) สำหรับ Voice, Downlink, Uplink ดังนั้นจึงเป็นเทคโนโลยีที่จัดอยู่ในกลุ่มของ Broadband Technology สำหรับการ Multiplexing ความถี่ของ Downlink/Uplink ออกมาจากสายโทรศัพท์และเชื่อมต่อเข้าไปยัง IP Network ซึ่งทางผู้ให้บริการจะติดตั้งอุปกรณ์ที่เรียกว่า Digital Subscriber Line Access Multiplexer (DSLAM) เพิ่มเข้าไปยังเครือข่ายของตน และทางฝั่งของผู้ใช้เองก็จำเป็นต้องเปลี่ยน Analog MODEM ของตน (และนำไปบริจาคให้กับพิพิธภัณฑ์) เป็น ADSL MODEM เพื่อที่จะ Modulation/Demodulation ข้อมูลจากคอมพิวเตอร์ไปเป็นย่านความถี่สำหรับ Uplink/Downlink ได้ (ดังแสดงตามรูปที่ 2)
รูปที่ 2 ADSL Connection Diagram
อาจมีคำถามตามมาว่าแล้วเราจะ Upgrade ตามไปทำไม ทำไมไม่ใช้ Analog MODEM ต่อไปล่ะ มีเหตุผลสำคัญที่เป็นประโยชน์กับผู้ใช้อยู่สองข้อที่ควร Upgrade เป็นอย่างยิ่ง ประการแรกคือความอิสระในการใช้งาน Voice และ Data คือสามารถใช้งานโทรศัพท์เพื่อการพูดคุยควบคู่ไปกับการใช้งาน Internet เนื่องจากมีการแบ่งย่านความถี่ของการรับส่งแยกออกจากกัน ซึ่งแต่เดิม Analog MODEM มีการใช้งานช่องความถี่ของ Voice ในการรับส่งข้อมูล จึงทำให้ขณะที่มีการใช้งาน Internet จึงไม่สามารถใช้โทรศัพท์พูดคุยได้ และในขณะที่ใช้โทรศัพท์ในการพูดคุย จะไม่สามารถใช้ Internet ได้ เพราะใช้ย่านความถี่เดียวกัน ซึ่งขณะใดขณะหนึ่งจำเป็นต้องใช้งานอย่างใดอย่างหนึ่งเท่านั้น
เหตุผลประการที่สองคือ Bandwidth สูง ซึ่งเป็นเหตุผลที่เหมาะสมกับการใช้งานในยุคของ Information เป็นอย่างยิ่ง เราจำเป็นต้องรับส่งข้อมูลมากขึ้น มี Internet Application ที่ต้องใช้งานมากขึ้น ซึ่งหมายถึงจำเป็นต้องมีการรับส่งข้อมูลระหว่างคอมพิวเตอร์และ Internet เพิ่มมากขึ้น และเนื่องจากข้อจำกัดของ Analog MODEM ด้วยเทคโนยีที่ใช้อยู่ถึงขีดจำกัดแล้ว ทำให้ Analog MODEM สามารถใช้กับอัตตราการรับส่งข้อมูลได้ไม่เกิน 56 kbps เท่านั้น ซึ่งแน่นอนว่าการใช้งานจึงเป็นไปอย่างจำกัด ไม่ค่อยจะทันใจผู้ใช้สมัยนี้เท่าไหร่นัก แต่สำหรับเทคโนโลยี ADSL นั้นสามารถมีอัตตราการรับส่งข้อมูลสูงสุดได้ถึง 8.448 Mbps (ประมาณ 150 เท่าของความเร็วสูงสุดของ Analog MODEM) แต่ที่มีให้บริการในเมืองไทย จะอยู่ที่ประมาณ 2.048 Mbps
จากเหตุผลทั้งสองข้อดังกล่าวคงเพียงพอที่จะหันมาใช้ Broadband Internet นะครับ
Network Information Services (NIS) enables you to create user accounts that can be shared across all systems on your network. The user account is created only on the NIS server. NIS clients download the necessary username and password data from the NIS server to verify each user login.
An advantage of NIS is that users need to change their passwords on the NIS server only, instead of every system on the network. This makes NIS popular in computer training labs, distributed software development projects or any other situation where groups of people have to share many different computers.
The disadvantages are that NIS doesn’t encrypt the username and password information sent to the clients with each login and that all users have access to the encrypted passwords stored on the NIS server. A detailed analysis of NIS security is beyond the scope of this book, but I suggest that you restrict its use to highly secure networks or to networks where access to non-NIS networks is highly restricted.
The Lightweight Directory Access Protocol (LDAP) offers similar features to NIS but has the advantage of supporting encryption without additional software and can support clients across multiple networks without the need for slave servers. It is for this reason that LDAP has become increasingly popular for this type of application.
To understand the benefits of NFS, consider an example. A school wants to set up a small computer lab for its students.
When searching for the RPMs, remember that the filename usually starts with the software package name followed by a version number, as in yp-tools-2.8-3.i386.rpm.
The lab instructor did some research and created an implementation plan:
You have the scenario and the plan, it’s time to get to work.
Here are the steps to configure the NFS server in this scenario:
1. Edit the /etc/exports file to allow NFS mounts of the /home directory with read/write access.
/home *(rw,sync)
2. Let NFS read the /etc/exports file for the new entry, and make /home available to the network with the exportfs command.
[root@bigboy tmp]# exportfs -a [root@bigboy tmp]#
3. Make sure the required nfs, nfslock, and portmap daemons are both running and configured to start after the next reboot.
[root@bigboy tmp]# chkconfig nfslock on [root@bigboy tmp]# chkconfig nfs on [root@bigboy tmp]# chkconfig portmap on [root@bigboy tmp]# service portmap start Starting portmapper: [ OK ] [root@bigboy tmp]# service nfslock start Starting NFS statd: [ OK ] [root@bigboy tmp]# service nfs start Starting NFS services: [ OK ] Starting NFS quotas: [ OK ] Starting NFS daemon: [ OK ] Starting NFS mountd: [ OK ] [root@bigboy tmp]#
After configuring the NFS server, we have to configure its clients, This will be covered next.
You also need to configure the NFS clients to mount their /home directories on the NFS server.
These steps archive the /home directory. In a production environment in which the /home directory would be actively used, you’d have to force the users to log off, backup the data, restore it to the NFS server, and then follow the steps below. As this is a lab environment, these prerequisites aren’t necessary.
1. Make sure the required netfs, nfslock, and portmap daemons are running and configured to start after the next reboot.
[root@smallfry tmp]# chkconfig nfslock on [root@smallfry tmp]# chkconfig netfs on [root@smallfry tmp]# chkconfig portmap on [root@smallfry tmp]# service portmap start Starting portmapper: [ OK ] [root@smallfry tmp]# service netfs start Mounting other filesystems: [ OK ] [root@smallfry tmp]# service nfslock start Starting NFS statd: [ OK ] [root@smallfry tmp]#
2. Keep a copy of the old /home directory, and create a new directory /home on which you’ll mount the NFS server’s directory.
[root@smallfry tmp]# mv /home /home.save [root@smallfry tmp]# mkdir /home [root@smallfry tmp]# ll / ... ... drwxr-xr-x 1 root root 11 Nov 16 20:22 home drwxr-xr-x 2 root root 4096 Jan 24 2003 home.save ... ... [root@smallfry tmp]#
3. Make sure you can mount bigboy’s /home directory on the new /home directory you just created. Unmount it once everything looks correct.
[root@smallfry tmp]# mount 192.168.1.100:/home /home/ [root@smallfry tmp]# ls /home ftpinstall nisuser quotauser smallfry www [root@smallfry tmp]# umount /home [root@smallfry tmp]#
4. Start configuring autofs automounting. Edit your /etc/auto.master file to refer to file /etc/auto.home for mounting information whenever the /home directory is accessed. After five minutes, autofs unmounts the directory.
#/etc/auto.master /home /etc/auto.home --timeout 600
5. Edit file /etc/auto.home to do the NFS mount whenever the /home directory is accessed. If the line is too long to view on your screen, you can add a \ character at the end to continue on the next line.
#/etc/auto.home * -fstype=nfs,soft,intr,rsize=8192,wsize=8192,nosuid,tcp \ 192.168.1.100:/home/&
6. Start autofs and make sure it starts after the next reboot with the chkconfig command.
[root@smallfry tmp]# chkconfig autofs on [root@smallfry tmp]# service autofs restart Stopping automount:[ OK ] Starting automount:[ OK ] [root@smallfry tmp]#
After doing this, you won’t be able to see the contents of the /home directory on bigboy as user root. This is because by default NFS activates the root squash feature, which disables this user from having privileged access to directories on remote NFS servers. You’ll be able to test this later after NIS is configured.
All newly added Linux users will now be assigned a home directory under the new remote /home directory. This scheme will make the users feel their home directories are local, when in reality they are automatically mounted and accessed over your network.
NFS only covers file sharing over the network. You now have to configure NIS login authentication for the lab students before the job is done. The configuration of the NIS server is not difficult, but requires many steps that you may overlook. Don’t worry, we’ll review each one in detail.
Note: In the early days, NIS was called Yellow Pages. The developers had to change the name after a copyright infringement lawsuit, yet many of the key programs associated with NIS have kept their original names beginning with yp.
All the packages required for NIS clients are a standard part of most Fedora installations. The ypserv package for servers is not.
Edit Your /etc/sysconfig/network File
You need to add the NIS domain you wish to use in the /etc/sysconfig/network file. For the school, call the domain NIS-SCHOOL-NETWORK.
#/etc/sysconfig/network NISDOMAIN="NIS-SCHOOL-NETWORK"
NIS servers also have to be NIS clients themselves, so you’ll have to edit the NIS client configuration file /etc/yp.conf to list the domain’s NIS server as being the server itself or localhost.
# /etc/yp.conf - ypbind configuration file ypserver 127.0.0.1
Start the necessary NIS daemons in the /etc/init.d directory and use the chkconfig command to ensure they start after the next reboot.
[root@bigboy tmp]# service portmap start Starting portmapper: [ OK ] [root@bigboy tmp]# service yppasswdd start Starting YP passwd service: [ OK ] [root@bigboy tmp]# service ypserv start Setting NIS domain name NIS-SCHOOL-NETWORK: [ OK ] Starting YP server services: [ OK ] [root@bigboy tmp]# [root@bigboy tmp]# chkconfig portmap on [root@bigboy tmp]# chkconfig yppasswdd on [root@bigboy tmp]# chkconfig ypserv on
Table 30.1 lists a summary of the daemon’s functions.
Daemon Name | Purpose |
---|---|
portmap | The foundation RPC daemon upon which NIS runs. |
yppasswdd | Lets users change their passwords on the NIS server from NIS clients |
ypserv | Main NIS server daemon |
ypbind | Main NIS client daemon |
ypxfrd | Used to speed up the transfer of very large NIS maps |
Make sure they are all running before continuing to the next step. You can use the rpcinfo command to do this.
[root@bigboy tmp]# rpcinfo -p localhost program vers proto port 100000 2 tcp 111 portmapper 100000 2 udp 111 portmapper 100009 1 udp 681 yppasswdd 100004 2 udp 698 ypserv 100004 1 udp 698 ypserv 100004 2 tcp 701 ypserv 100004 1 tcp 701 ypserv [root@bigboy tmp]#
The ypbind and ypxfrd daemons won’t start properly until after you initialize the NIS domain. You’ll start these daemons after initialization is completed.
Now that you have decided on the name of the NIS domain, you’ll have to use the ypinit command to create the associated authentication files for the domain. You will be prompted for the name of the NIS server, which in this case is bigboy.
With this procedure, all nonprivileged accounts are automatically accessible via NIS.
[root@bigboy tmp]# /usr/lib/yp/ypinit -m At this point, we have to construct a list of the hosts which will run NIS servers. bigboy is in the list of NIS server hosts. Please continue to add the names for the other hosts, one per line. When you are done with the list, type a <control D>. next host to add: bigboy next host to add: The current list of NIS servers looks like this: bigboy Is this correct? [y/n: y] y We need a few minutes to build the databases... Building /var/yp/NIS-SCHOOL-NETWORK/ypservers... Running /var/yp/Makefile... gmake[1]: Entering directory `/var/yp/NIS-SCHOOL-NETWORK' Updating passwd.byname... Updating passwd.byuid... Updating group.byname... Updating group.bygid... Updating hosts.byname... Updating hosts.byaddr... Updating rpc.byname... Updating rpc.bynumber... Updating services.byname... Updating services.byservicename... Updating netid.byname... Updating protocols.bynumber... Updating protocols.byname... Updating mail.aliases... gmake[1]: Leaving directory `/var/yp/NIS-SCHOOL-NETWORK' bigboy has been set up as a NIS master server. Now you can run ypinit -s bigboy on all slave server. [root@bigboy tmp]#
Note: Make sure portmap is running before trying this step or you’ll get errors, such as:
failed to send 'clear' to local ypserv: RPC: Port mapper failureUpdating group.bygid...
You will have to delete the /var/yp/NIS-SCHOOL-NETWORK directory and restart portmap, yppasswd, and ypserv before you’ll be able to do this again successfully.
You can now start the ypbind and the ypxfrd daemons because the NIS domain files have been created.
[root@bigboy tmp]# service ypbind start Binding to the NIS domain: [ OK ] Listening for an NIS domain server. [root@bigboy tmp]# service ypxfrd start Starting YP map server: [ OK ] [root@bigboy tmp]# chkconfig ypbind on [root@bigboy tmp]# chkconfig ypxfrd on
All the NIS daemons use RPC port mapping and, therefore, are listed using the rpcinfo command when they are running correctly.
[root@bigboy tmp]# rpcinfo -p localhost program vers proto port 100000 2 tcp 111 portmapper 100000 2 udp 111 portmapper 100003 2 udp 2049 nfs 100003 3 udp 2049 nfs 100021 1 udp 1024 nlockmgr 100021 3 udp 1024 nlockmgr 100021 4 udp 1024 nlockmgr 100004 2 udp 784 ypserv 100004 1 udp 784 ypserv 100004 2 tcp 787 ypserv 100004 1 tcp 787 ypserv 100009 1 udp 798 yppasswdd 600100069 1 udp 850 fypxfrd 600100069 1 tcp 852 fypxfrd 100007 2 udp 924 ypbind 100007 1 udp 924 ypbind 100007 2 tcp 927 ypbind 100007 1 tcp 927 ypbind [root@bigboy tmp]#
New NIS users can be created by logging into the NIS server and creating the new user account. In this case, you’ll create a user account called nisuser and give it a new password.
Once this is complete, you then have to update the NIS domain’s authentication files by executing the make command in the /var/yp directory.
This procedure makes all NIS-enabled, nonprivileged accounts become automatically accessible via NIS, not just newly created ones. It also exports all the user’s characteristics stored in the /etc/passwd and /etc/group files, such as the login shell, the user’s group, and home directory.
[root@bigboy tmp]# useradd -g users nisuser [root@bigboy tmp]# passwd nisuser Changing password for user nisuser. New password: Retype new password: passwd: all authentication tokens updated successfully. [root@bigboy tmp]# cd /var/yp [root@bigboy yp]# make gmake[1]: Entering directory `/var/yp/NIS-SCHOOL-NETWORK' Updating passwd.byname... Updating passwd.byuid... Updating netid.byname... gmake[1]: Leaving directory `/var/yp/NIS-SCHOOL-NETWORK' [root@bigboy yp]#
You can check to see if the user’s authentication information has been updated by using the ypmatch command, which should return the user’s encrypted password string.
[root@bigboy yp]# ypmatch nisuser passwd nisuser:$1$d6E2i79Q$wp3Eo0Qw9nFD/::504:100::/home/nisuser:/bin/bash [root@bigboy yp]
You can also use the getent command, which has similar syntax. Unlike ypmatch, getent doesn’t provide an encrypted password when run on an NIS server, it just provides the user’s entry in the /etc/passwd file. On a NIS client, the results are identical with both showing the encrypted password.
[root@bigboy yp]# getent passwd nisuser nisuser:x:504:100::/home/nisuser:/bin/bash [root@bigboy yp]#
Now that the NIS server is configured, it’s time to configure the NIS clients. There are a number of related configuration files that you need to edit to get it to work. Take a look at the procedure.
The authconfig
or the authconfig-tui
program automatically configures your NIS files after prompting you for the IP address and domain of the NIS server.
[root@smallfry tmp]# authconfig-tui
Once finished, it should create an /etc/yp.conf file that defines, amongst other things, the IP address of the NIS server for a particular domain. It also edits the /etc/sysconfig/network file to define the NIS domain to which the NIS client belongs.
# /etc/yp.conf - ypbind configuration file domain NIS-SCHOOL-NETWORK server 192.168.1.100 #/etc/sysconfig/network NISDOMAIN=NIS-SCHOOL-NETWORK
In addition, the authconfig program updates the /etc/nsswitch.conf file that lists the order in which certain data sources should be searched for name lookups, such as those in DNS, LDAP, and NIS. Here you can see where NIS entries were added for the important login files.
#/etc/nsswitch.conf passwd: files nis shadow: files nis group: files nis
Note: You can also locate a sample NIS nsswitch.conf file in the /usr/share/doc/yp-tools* directory.
Start the ypbind NIS client, and portmap daemons in the /etc/init.d directory and use the chkconfig command to ensure they start after the next reboot. Remember to use the rpcinfo command to ensure they are running correctly.
[root@smallfry tmp]# service portmap start Starting portmapper: [ OK ] [root@smallfry tmp]# service ypbind start Binding to the NIS domain: Listening for an NIS domain server. [root@smallfry tmp]# [root@smallfry tmp]# chkconfig ypbind on [root@smallfry tmp]# chkconfig portmap on
Note: Remember to use the rpcinfo -p localhost command to make sure they all started correctly.
As the configuration examples refer to the NIS client and server by their hostnames, you’ll have to make sure the names resolve correctly to IP addresses. This can be configured either in DNS, when the hosts reside in the same domain, or more simply by editing the /etc/hosts file on both Linux boxes.
# # File: /etc/hosts (smallfry) # 192.168.1.100 bigboy # # File: /etc/hosts (bigboy) # 192.168.1.102 smallfry
You can run the ypcat, ypmatch, and getent commands to make sure communication to the server is correct.
[root@smallfry tmp]# ypcat passwd nisuser:$1$Cs2GMe6r$1hohkyG7ALrDLjH1:505:100::/home/nisuser:/bin/bash quotauser:!!:503:100::/home/quotauser:/bin/bash ftpinstall:$1$8WjAVtes$SnRh9S1w07sYkFNJwpRKa.:502:100::/:/bin/bash www:$1$DDCi/OPI$hwiTQ.L0XqYJUk09Bw.pJ/:504:100::/home/www:/bin/bash smallfry:$1$qHni9dnR$iKDs7gfyt..BS9Lry3DAq.:501:100::/:/bin/bash [root@smallfry tmp]# [root@smallfry tmp]# ypmatch nisuser passwd nisuser:$1$d6E2i79Q$wp3Eo0Qw9nFD/:504:100::/home/nisuser:/bin/bash [root@smallfry tmp]# [root@smallfry tmp]# getent passwd nisuser nisuser:$1$d6E2i79Q$wp3Eo0Qw9nFD/:504:100::/home/nisuser:/bin/bash [root@smallfry tmp]#
Possible sources of error would include:
Try to eliminate these areas as sources of error and refer to the syslog /var/log/messages file on the client and server for entries that may provide additional clues.
Once your basic NIS functionality testing is complete, try to test a remote login. Failures in this area could be due to firewalls blocking TELNET or SSH access and the TELNET and SSH server process not being started on the clients.
Try logging into the NIS client via telnet if it is enabled
[root@bigboy tmp]# telnet 192.168.1.201 Trying 192.168.1.201... Connected to 192.168.1.201. Escape character is '^]'. Red Hat Linux release 9 (Shrike) Kernel 2.4.20-6 on an i686 login: nisuser Password: Last login: Sun Nov 16 22:03:51 from 192-168-1-100.simiya.com [nisuser@smallfry nisuser]$
Try logging into the NIS client via SSH.
[root@bigboy tmp]# ssh -l nisuser 192.168.1.102 nisuser@192.168.1.102's password: [nisuser@smallfry nisuser]$
In some versions of Linux, the NIS client’s SSH daemon doesn’t re-read the /etc/nsswitch.conf file you just modified until SSH is restarted. SSH logins, therefore, won’t query the NIS server until this is done. Restart SSH on the NIS client.
[root@smallfry root]# service sshd restart Stopping sshd:[ OK ] Starting sshd:[ OK ] [root@smallfry root]#
NIS relies a lot on broadcast traffic to operate, which prevents you from having an NIS server on a different network from the clients. You can avoid this problem on your local subnet by using slave servers that are configured to automatically synchronize their NIS data with that of the single master server.
You can also consider placing multiple NIS servers on a single subnet for the sake of redundancy. To do this, configure the NIS clients to have multiple NIS servers for the domain in the /etc/yp.conf file.
In this scenario, you need to add an NIS slave server named nisslave (IP address 192.168.1.254) to the NIS-SCHOOL-NETWORK NIS domain. You also must configure the NIS master server, bigboy, to push its database map information to the slave whenever there is an update. Here are the steps you need.
1. As you’re referring to our servers by their hostnames, you’ll have to make sure the names resolve correctly to IP addresses. This can be done either in DNS, when the hosts reside in the same domain, or more simply by editing the /etc/hosts files on both servers as seen in Table 30.2.
Master (Bigboy) | Slave (Nisslave) |
---|---|
# # File: /etc/hosts (Bigboy) # 192.168.1.254 nisslave |
# # File: /etc/hosts (Nisslave) # 192.168.1.100 bigboy |
2. Configure the NIS slave as a NIS client of itself in the /etc/yp.conf file, and configure the NIS domain in the /etc/sysconfig/network file as seen in Table 30.3.
/etc/yp.conf | /etc/sysconfig/network |
---|---|
# # File: /etc/yp.conf (Bigboy) # ypserver 127.0.0.1 |
# # File: /etc/sysconfig/network # NISDOMAIN="NIS-SCHOOL-NETWORK" |
3. On the slave server, run ypbind so the slave can query the master server.
[root@nisslave tmp]# service portmap start Starting portmapper: [ OK ] [root@nisslave tmp]# service ypbind start Binding to the NIS domain: Listening for an NIS domain server. [root@nisslave tmp]# [root@nisslave tmp]# chkconfig portmap on [root@nisslave tmp]# chkconfig ypbind on
4. Optimize database map transfers by the NIS map transfer daemon, which should the started on both the master and slave.
[root@nisslave tmp]# service ypxfrd start Starting YP map server: [ OK ] [root@nisslave tmp]# [root@nisslave tmp]# chkconfig ypxfrd on [root@bigboy tmp]# service ypxfrd start Starting YP map server: [ OK ] [root@bigboy tmp]# [root@bigboy tmp]# chkconfig ypxfrd on
5. Do a simple database query of the master from the slave using the ypwhich command with the -m (master) switch. You should get a listing of all the tables.
[root@nisslave tmp]# ypwhich -m mail.aliases bigboy group.bygid bigboy passwd.byuid bigboy rpc.bynumber bigboy ... ... [root@nisslave tmp]#
6. Do an initial database download to the slave from the master with the ypinit command using the -s switch for a slave-type operation and specifying server bigboy as the master from which the data is to be obtained. You should see "Trying ypxfrd – success" messages. If the messages say "Trying ypxfrd – not running," then start ypxfrd on both servers.
[root@nisslave tmp]# /usr/lib/yp/ypinit -s bigboy We will need a few minutes to copy the data from bigboy. Transferring services.byservicename... Trying ypxfrd ... success Transferring group.byname... Trying ypxfrd ... success ... ... nisslave's NIS data base has been set up. If there were warnings, please figure out what went wrong, and fix it. At this point, make sure that /etc/passwd and /etc/group have been edited so that when the NIS is activated, the data bases you have just created will be used, instead of the /etc ASCII files. [root@nisslave tmp]#
If your database is corrupt or your /etc/hosts files are incorrect, you’ll get map enumeration errors as shown. Use the make command again to rebuild your database on the master when necessary.
[root@nisslave tmp]# /usr/lib/yp/ypinit -s bigboy Can't enumerate maps from bigboy. Please check that it is running. [root@nisslave tmp]#
7. Now that the data has been successfully downloaded, it’s time to make the slave server serve NIS clients with ypserv.
[root@nisslave tmp]# service ypserv start Starting YP server services: [root@nisslave tmp]# [root@nisslave tmp]# chkconfig ypxfrd on
8. Log on to the master server. Add the slave server to the master server’s database map by editing the /var/yp/ypservers file on the master.
[root@bigboy yp]# cd /tmp [root@bigboy tmp]# cd /var/yp/ [root@bigboy yp]# vi ypservers
Add nisslave to the file.
# # File: /var/yp/ypservers # bigboy nisslave
9. The make file in the /var/yp directory defines how the NIS server will build the database map and how the master will relate to the NIS slave. Make a copy of the master’s make file for safekeeping.
[root@bigboy yp]# cp Makefile Makefile.old
10. Edit the make file to allow the master to push maps to the slave.
# # File: /var/vp/Makefile # # # Allow the master to do database pushes to the slave # NOPUSH=false
11. Use the make command to rebuild the database. The make command automatically pushes database updates to the servers listed in the /var/yp/servers file.
[root@bigboy yp]# make gmake[1]: Entering directory `/var/yp/NIS-SCHOOL-NETWORK' Updating ypservers... YPPUSH: gethostbyname(): Success YPPUSH: using not FQDN name gmake[1]: Leaving directory `/var/yp/NIS-SCHOOL-NETWORK' gmake[1]: Entering directory `/var/yp/NIS-SCHOOL-NETWORK' Updating netid.byname... YPPUSH: gethostbyname(): Success YPPUSH: using not FQDN name gmake[1]: Leaving directory `/var/yp/NIS-SCHOOL-NETWORK' [root@bigboy yp]#
12. On the slave server, create a cron file in the /etc/crond.d directory, in this case named nis_sync, that will run periodic database downloads from the master server. This helps to ensure that the slave servers have current databases even if they miss updates from the master in the event the school goes offline for maintenance. Restart the cron daemon so that the configuration in this file becomes active.
[root@nisslave yp]# vi /etc/cron.d/nis_sync # # File: /etc/cron.d/nis_sync # 20 * * * * /usr/lib/yp/ypxfr_1perhour 40 6 * * * /usr/lib/yp/ypxfr_1perday 55 6,18 * * * /usr/lib/yp/ypxfr_2perday [root@nisslave yp]# service crond restart
That’s a lot of work but it’s still not over. There is one final configuration step that needs to be done on the NIS clients before you’re finished.
Edit the /etc/yp.conf file on all the clients to include nisslave, and restart ypbind.
# # File: /etc/yp.conf (Smallfry) # domain NIS-SCHOOL-NETWORK server 192.168.1.100 domain NIS-SCHOOL-NETWORK server 192.168.1.254 [root@smallfry tmp]# service ypbind restart Shutting down NIS services: [ OK ] Binding to the NIS domain: [ OK ] Listening for an NIS domain server.. [root@smallfry tmp]#
You should also test to make sure your users can change their NIS passwords from the NIS clients with the yppasswd command. The process is different whether there is only a single NIS master or a master-slave server relationship.
When there is only a single NIS server, password changes can be made only on the NIS server using the yppasswd command.
Users can change their passwords by logging into the NIS server and issuing the yppasswd command.
[nisuser@bigboy nisuser]$ yppasswd Changing NIS account information for nisuser on bigboy.my-site.com. Please enter old password: Changing NIS password for nisuser on bigboy.my-site.com. Please enter new password: Please retype new password: The NIS password has been changed on bigboy.my-site.com. [nisuser@bigboy nisuser]$
The root user can change other users’ passwords issuing the yppasswd command with the -p switch that specifies the username that needs the change.
[root@bigboy tmp]# yppasswd -p nisuser Changing NIS account information for nisuser on bigboy.my-site.com. Please enter root password: Changing NIS password for nisuser on bigboy.my-site.com. Please enter new password: Please retype new password: The NIS password has been changed on bigboy.my-site.com. [root@bigboy tmp]#
With an NIS master and slave pair configuration, passwords can be changed on the NIS clients or the NIS slave, but not on the NIS master.
There are a number of unexpected errors you may find when changing passwords – errors that have nothing to do with bad typing.
Running the yppasswd command on the wrong client or server depending on your NIS master and slave configuration can cause segmentation fault errors. (Make sure you follow the chapter’s guidelines for password changes!) Here are some sample password change failures on an NIS client with only one NIS master server.
[nisuser@smallfry nisuser]$ yppasswd Segmentation fault [nisuser@smallfry nisuser]$ [root@smallfry root]# yppasswd -p nisuser Segmentation fault [root@smallfry root]#
The yppasswdd daemon must be running on both the client and server for password changes to work correctly. When they aren’t running, you’ll get errors.
[root@smallfry etc]# yppasswd -p nisuser yppasswd: yppasswdd not running on NIS master host ("bigboy"). [root@smallfry etc]#
You’ll also get a similar error if you attempt to change an NIS password on an NIS master server in a master and slave configuration.
In many cases NFS, isn’t used to create a centralized home directory for users and, therefore, you’ll have to create it on each NIS client and not on the server.
This example creates the home directory for the NIS client, smallfry. After doing this, you have to copy a BASH login profile file into it and modify the ownership of the directory and all the files to user nisuser.
Logins should proceed normally once this has been done and all the other steps have been followed.
[root@smallfry tmp]# mkdir /home/nisuser [root@smallfry tmp]# chmod 700 /home/nisuser/ [root@smallfry tmp]# ll /home total 2 drwx------ 2 nisuser users 1024 Aug 4 08:05 nisuser [root@smallfry tmp]# [root@smallfry tmp]# cp /etc/skel/.* /home/nisuser/ cp: omitting directory `/etc/skel/.' cp: omitting directory `/etc/skel/..' cp: omitting directory `/etc/skel/.kde' [root@smallfry tmp]# chown -R nisuser:users /home/nisuser [root@smallfry tmp]#
Troubleshooting is always required as any part of your daily routine, NIS is no exception. Here are some simple steps to follow to get it working again.
1. The rpcinfo provides a list of TCP ports that your NIS client or server is using. Make sure you can TELNET to these ports from the client to the server and vice versa. If this fails, make sure all the correct NIS daemons are running and that there are no firewalls blocking traffic on the network or on the servers themselves. These ports change from time to time, so memorizing them won’t help much.
The example tests from the client to the server.
[root@bigboy tmp]# rpcinfo -p program vers proto port 100000 2 tcp 111 portmapper 100000 2 udp 111 portmapper 100024 1 udp 32768 status 100024 1 tcp 32768 status 391002 2 tcp 32769 sgi_fam 100009 1 udp 1018 yppasswdd 100004 2 udp 611 ypserv 100004 1 udp 611 ypserv 100004 2 tcp 614 ypserv 100004 1 tcp 614 ypserv 100007 2 udp 855 ypbind 100007 1 udp 855 ypbind 100007 2 tcp 858 ypbind 100007 1 tcp 858 ypbind 600100069 1 udp 874 fypxfrd 600100069 1 tcp 876 fypxfrd [root@bigboy tmp]# [root@smallfry tmp]# telnet 192.168.1.100 858 Trying 10.41.32.71... Connected to 10.41.32.71. Escape character is '^]'. ^] telnet> quit Connection closed. [root@smallfry tmp]#
2. Always use the ypmatch, getent, and ypwhich commands to check your NIS connectivity. If there is any failure, check your steps over again and you should be able to find the source of your problem.
3. Do not fail to create a user’s home directory, set its permissions, and copy the /etc/skel files correctly. If you forget, which is a common error, your users may have incorrect login prompts and no ability to create files in their home directories.
It can never be overemphasized that one of the best places to start troubleshooting is by looking in your error log files in the /var/log directory. You’ll save a lot of time and effort if you always refer to them whenever the problem doesn’t appear to be obvious.
NIS is a very useful tool for centralized login management, but it has two shortcomings: NIS clients are typically limited to Unix or Linux operating systems, and the password information passes over the network unencrypted.
Newer authentication schemes overcome these issues. For example, LDAP, provides both encryption and the ability to be used on varied types of equipment. Unfortunately older operating systems don’t support it, making NIS the preferred option in some cases.
As always, explore your options when deciding on a centralized login scheme. A wrong decision could haunt you for a long time.
telnet [host] [port] Connect to host (25 (SMTP), 109/110 (POP3), 21 (FTP), 20 (FTP data) )
ssh -l [user] [host] Secure telnet to host
who Who is connected
finger [-l @host] Display info about logged on users
finger [user] Display info about user
whois [-h host name] Scans for a name or handle
whoami Display the effective current username
nslookup Query domain name servers interactively
route Routing (add host/net target gateway 0)
netstat -a|more Routing table. Show network status
ifconfig [device] Show the stats of network device, or all devices: -a
traceroute [ip_address] Tracing IP packet from this host to destination
Jobs:
ps List current processes (ps -aef | grep $USER)
CTRL + Z Suspend
kill [pid] / CTRL + C Kill a job (use pid returned by ps; -9 exit immediately)
pwd Display the pathname of the current working directory
cd [dirname] Change to directory dirname (cd without dirname wil go to your home
directory, cd .. moves one directory up, cd ~username moves you to
username’s homedir)
mkdir Make directory
rm, rmdir [dirname] Remove (unlink) files or directories
ln -s [realpath alias] Make symbolic links to files
df -h Report free disk space on file systems
fsck File system consistency check and interactive repair