blog'o thnet

I am always looking for some good IT cheat sheets, and for a lots of thing. Here is one of my favorite web site around network technologies. Interestingly, this site propose some regularly updated quick reference guides for the network, and are classified under the following categories (at the time of this writing):

• Protocols
• Applications
• Reference
• Syntax
• Technologies
• Miscellaneous

You can find them all at the Cheat Sheets Library section.

As the author wrote on his blog, if you notice an error or would like to see a new cheat sheet on a specific topic, don't hesitate and drop him a line.

Recently, while adding availability features to some of our AIX DLPARs (Dynamic Logical PARtitions), i went through this very interesting (and well written) reading which explain why and how to use, deploy and configure properly some of the very nice network features on the AIX operating system: EtherChannel and Network Interface Backup. In short, EtherChannel represent a network port aggregation technology that allow multiple Ethernet adapters to create a single pseudo-Ethernet device. In its second form, known as Network Interface Backup, it protects against network-SPOF by providing failure detection and failover mechanism.

1. soul is the hostname of the master NIS server for a given domain
2. kitchen is the hostname of the slave NIS server for a given domain
3. bento is the hostname of the NFS server
4. nfs is an alias (CNAME) for the NFS server

NFS configuration, logged on bento

Just add the wanted share in the export list on server bento. On Sun Solaris, it is done as follow:

# cat << EOF >> /etc/dfs/dfstab
share -F nfs -o rw -d "Applications repository, NFS shared" /export/bento/apps
EOF

The file system /export/bento/apps must already be available.

Start the nfsd service (and associated daemons: mountd, statd and lockd) if necessary:

# /etc/init.d/nfs.server start

Or simply export the new share:

# shareall

NIS configuration, logged on soul

Because all of the automounted NFS clients (in particular Solaris, AIX and GNU/Linux) know how to use automount maps shared via the NIS protocol, the centralized auto_apps (SYSV style) map resides on the master NIS server, soul.

Since this is a new map to add, there is a little more to do here.

Create the map in the DIR (in NIS parlance) directory:

# touch /etc/ivyp/auto_apps
# ci -i /etc/ivyp/auto_apps
/*
 * Description message: "Automounter map for the applications repository,
 * NFS shared.".
 */
# co -l /etc/yp/auto_apps
# cat << EOF > /etc/ivyp/auto_apps
* -rw,hard,bg,intr nfs:/export/bento/apps/${OSNAME}/${CPU}/${NATISA}/${OSREL}/?
EOF
# ci -u /etc/ivyp/auto_apps

The RCS commands may (and must) be used through the ivv.sh wrapper script.

Teach the customized NIS infrastructure (based on GNU tools, not the native ones) about the new map:

# diff -u /var/yp/GNUmakefile.2005-08-25 /var/yp/GNUmakefile
--- /var/yp/GNUmakefile.2005-08-25      Thu Aug 25 13:18:31 2005
+++ /var/yp/GNUmakefile Thu Aug 25 14:30:04 2005
@@ -76,6 +76,7 @@
 AUTONT=auto_nt
 AUTOALT=auto_alt
 AUTODIRECT=auto_direct
+AUTOAPPS=auto_apps
 else
 AUTOMASTER=auto.master
 AUTOHOME=auto.home
@@ -83,6 +84,7 @@
 AUTONT=auto.nt
 AUTOALT=auto.alt
 AUTODIRECT=auto.direct
+AUTOAPPS=auto.apps
 endif
 GNUGREP=/usr/local/bin/ggrep
 MALIASES=$(YPDBDIR)/$(DOM)/mail.aliases
@@ -96,7 +98,7 @@
 
 all:: passwd group hosts ethers networks rpc services protocols \
        netgroup bootparams aliases publickey netid netmasks c2secure \
-       timezone auto.master auto.home auto.soft auto.nt auto.alt auto.direct \
+       timezone auto.master auto.home auto.soft auto.nt auto.alt auto.apps auto.direct \
        printcap dmmo printers.conf virtualip
 
 diams: dmmo_applis dmmo_sites dmmo_users ypservers
@@ -424,6 +426,22 @@
                echo "couldn't find $(DIR)/auto.alt"; \
        fi
 
+auto.apps.time:  $(DIR)/$(AUTOAPPS)
+       -@if [ -f $(DIR)/$(AUTOAPPS) ]; then \
+               sed -e "/^#/d" -e s/#.*$$// $(DIR)/$(AUTOAPPS) \
+               | $(MAKEDBM) - $(YPDBDIR)/$(DOM)/auto.apps; \
+               touch auto.apps.time; \
+               echo "updated auto.apps"; \
+               if [ ! $(NOPUSH) ]; then \
+                       $(YPPUSH) auto.apps; \
+                       echo "pushed auto.apps"; \
+               else \
+               : ; \
+               fi \
+       else \
+               echo "couldn't find $(DIR)/auto.apps"; \
+       fi
+
 printcap.time: $(DIR)/ypprintcap
        -@if [ -f $(DIR)/yp$(@:.time=) ]; then \
                sed < $(DIR)/yp$(@:.time=) \
@@ -686,6 +704,7 @@
 auto.soft: auto.soft.time
 auto.nt: auto.nt.time
 auto.alt: auto.alt.time
+auto.apps: auto.apps.time
 auto.direct: auto.direct.time
 printcap: printcap.time
 printers.conf: printers.conf.time
@@ -710,6 +729,7 @@
 $(DIR)/$(AUTOSOFT):
 $(DIR)/$(AUTONT):
 $(DIR)/$(AUTOALT):
+$(DIR)/$(AUTOAPPS):
 $(DIR)/$(AUTODIRECT):
 $(DIR)/ypprintcap:
 $(DIR)/printers.conf:

At this stage, the new map must be first manually transferred on the slave NIS server.

Create the corresponding map files (*.dir and *.pag ) only, using:

# cd /etc/ivyp
# gmake -C /var/yp NOPUSH="YES"

Log in on the slave server (a Sun system), for example kitchen :

# /usr/lib/netsvc/yp/ypxfr -h soul auto.apps
# ls -l /var/yp/`domainname`/auto.apps.*
-rw-r--r--   1 root     root           0 Aug 25 18:10 /var/yp/`domainname`/auto.apps.dir
-rw-r--r--   1 root     root        1024 Aug 25 18:10 /var/yp/`domainname`/auto.apps.pag

Note: You can know which hostname is(are) currently set up as slave server(s) using:

# cd /var/yp/`domainname`
# makedbm -u ypservers
YP_LAST_MODIFIED 1072719185
YP_MASTER_NAME soul
kitchen
timal

Then, on the master server, really push the map this time:

# cd /etc/ivyp
# gmake -C /var/yp

Now, the new mount point and sub-tree must be ready and available to all your properly configured clients, as found in the following online documents:

1. Use the NIS and NFS Infrastructure on AIX 5L
2. Use the NIS and NFS Infrastructure on Red Hat Advanced Server 2.1

Decided to upgrade the Cayman 3366-ENT ADSL Gateway from Netopia, currently hosting the public link for the Thilelli.NET Project. All went smooth and well. The gateway is now at the latest firmware level available (8.5.0 at the time of this writing).

At the same time, try to avoid some recurrent problem on the link (seems ok but doesn't let real traffic to pass through it) helped by the 24-Hour Scheduled Connection procedure. Waiting to see if it really works for our site... thanks to our ISP for providing a nice administration and status page.

Here are the steps to be able to use the current NIS and NFS infrastructure from an AIX server:

# cat /etc/resolv.conf  
domain          dev.example.com
nameserver      10.239.208.24
nameserver      10.251.140.96
search          dev.example.com int.example.com prod.example.com
#
# TERM=vt220 smitty
/*
 * Communications Applications and Services
 *  TCP/IP
 *   Further Configuration
 *    Name Resolution
 *     Hosts Table (/etc/hosts)
 *      Add a Host
 *       INTERNET ADDRESS (dotted decimal)               [10.254.234.22]
 *       HOST NAME                                       [neptune.dev.example.com]
 *       ALIAS(ES) (if any - separated by blank space)   [neptune]
 *       COMMENT (if any - for the host entry)           [NIS server for domain devex]
 *  NFS
 *   Network Information Service (NIS)
 *    Configure / Modify NIS
 *     Change NIS Domain Name of this Host
 *      Domain name of this host                        [devex]
 *     Configure this Host as a NIS Client
 *      NIS server - required if there are              [neptune]
 *   Network File System (NFS)
 *    Configure NFS on This System
 *     Start Automounter
 *      PARAMETERS to be used for the automount daemon  [-n]
 */

Launch the automountd at run-level #2:

# cat << EOF > /etc/rc.d/rc2.d/Sautomountd
#!/usr/bin/env ksh
#################################################################
# name: {K|S}automountd
# purpose: script that will start or stop the automountd service.
#################################################################

case "$1" in
start)
  /usr/sbin/automount -n
  ;;
stop)
  stopsrc -g autofs
  ;;
*)
  echo "Usage: $0 {start|stop}"
  exit 1
esac

exit 0
EOF
# ln /etc/rc.d/rc2.d/Sautomountd /etc/rc.d/rc2.d/Kautomountd
# chmod 754 /etc/rc.d/rc2.d/?automountd

In the same time, modify the automountd service to add some arguments that must be passed to the program. This is a necessary step to be able to automount the correct remote path using our customized autofs server. Here is how to do so:

# chssys -s automountd -a "-DOSNAME=`uname -s` -DCPU=`uname -p` -DNATISA=`bootinfo -K` -DOSREL=`uname -v`.`uname -r`"
# stopsrc -g autofs
# /usr/sbin/automount -n

Very important

To resolve information correctly, it was needed to explicitly specify the ordering of name resolution and hosts setting in /etc/netsvc.conf. This file corresponds to /etc/nsswitch.conf under Solaris, GNU/Linux or the BSDs for hosts name resolution. For example:

# cat << EOF >> /etc/netsvc.conf
hosts = local, nis, bind
EOF