rev.dennis

First download the almost 800Mb file from nagios (it usually comes with a 60 day trial period) then follow the screenshots

First download the almost 800Mb file from nagios (it usually comes with a 60 day trial period) then follow the screenshots

First let's install the pre-req's INSTALL APACHE yum install httpd -y service httpd start chkconfig httpd on NOTE: If you get an error like The fix is to add your IPAddress and hostname to /etc/hosts Allow port 80 through the builtin firewall (iptables) vi /etc/sysconfig/iptables Add the following line -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT Restart the builtin firewall service iptables restart Test that Apache is working by opening a browser and navigating to http://localhost/ or http://server-ip-address/ INSTALL MySQL yum install mysql mysql-server -y Start MySQL Service service mysqld start Turn mysql service each time your server reboots chkconfig mysqld on Set the mysql root password mysql_secure_installation INSTALL PHP yum install php -y Create a test php file vi /var/www/html/testphp.php Add the following <?php phpinfo(); ?> Restart Apache service httpd restart See if your PHP is working by loading that testphp.php file you created http://server-ip-address/testphp.php Install mysql plugin for php yum install php-mysql -y INSTALL phpMyAdmin PreReq is to add distribution that holds the phpmyadmin package to yum repository wget http://epel.mirror.net.in/epel/6/i386/epel-release-6-8.noarch.rpm rpm -Uvh epel-release-6-8.noarch.rpm yum repolist installing phpmyadmin yum install phpmyadmin -y cp /usr/share/phpMyAdmin/config.sample.inc.php /usr/share/phpMyAdmin/config.inc.php vi /usr/share/phpMyAdmin/config.inc.php change cookie to http /* Authentication type */ $cfg['Servers'][$i]['auth_type'] = 'http'; edit config to allow access vi /etc/httpd/conf.d/phpMyAdmin.conf Comment out entire # # # # Apache 2.4 # Require local # # # # Apache 2.2 # Order Deny,Allow # Deny from All # Allow from 127.0.0.1 # Allow from ::1 # # Restart Apache service httpd restart Test phpMyAdmin by navigating to http://server-ip-address/phpmyadmin/ INSTALL NAGIOS cd /tmp wget http://assets.nagios.com/downloads/nagiosxi/xi-latest.tar.gz tar xzf xi-latest.tar.gz cd /tmp/nagiosxi ./fullinstall

First let's install the pre-req's INSTALL APACHE yum install httpd -y service httpd start chkconfig httpd on NOTE: If you get an error like The fix is to add your IPAddress and hostname to /etc/hosts Allow port 80 through the builtin firewall (iptables) vi /etc/sysconfig/iptables Add the following line -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT Restart the builtin firewall service iptables restart Test that Apache is working by opening a browser and navigating to http://localhost/ or http://server-ip-address/ INSTALL MySQL yum install mysql mysql-server -y Start MySQL Service service mysqld start Turn mysql service each time your server reboots chkconfig mysqld on Set the mysql root password mysql_secure_installation INSTALL PHP yum install php -y Create a test php file vi /var/www/html/testphp.php Add the following <?php phpinfo(); ?> Restart Apache service httpd restart See if your PHP is working by loading that testphp.php file you created http://server-ip-address/testphp.php Install mysql plugin for php yum install php-mysql -y INSTALL phpMyAdmin PreReq is to add distribution that holds the phpmyadmin package to yum repository wget http://epel.mirror.net.in/epel/6/i386/epel-release-6-8.noarch.rpm rpm -Uvh epel-release-6-8.noarch.rpm yum repolist installing phpmyadmin yum install phpmyadmin -y cp /usr/share/phpMyAdmin/config.sample.inc.php /usr/share/phpMyAdmin/config.inc.php vi /usr/share/phpMyAdmin/config.inc.php change cookie to http /* Authentication type */ $cfg['Servers'][$i]['auth_type'] = 'http'; edit config to allow access vi /etc/httpd/conf.d/phpMyAdmin.conf Comment out entire # # # # Apache 2.4 # Require local # # # # Apache 2.2 # Order Deny,Allow # Deny from All # Allow from 127.0.0.1 # Allow from ::1 # # Restart Apache service httpd restart Test phpMyAdmin by navigating to http://server-ip-address/phpmyadmin/ INSTALL NAGIOS cd /tmp wget http://assets.nagios.com/downloads/nagiosxi/xi-latest.tar.gz tar xzf xi-latest.tar.gz cd /tmp/nagiosxi ./fullinstall

I'm not a big fan of not seeing what's going on during boot up no matter what the operating system is. Usually most operating systems will display a pretty (or ugly) splash screen to hide the craziness of loading up what's needed to get the operating system up and running. Here is how to change Ubuntu to show everything going on during boot up Temporary (this will only happen this one time so you can see if you like it) When you get to the Grub boot menu (hold left shift on boot), edit the top option by pressing e and search the boot command until you see the two words "quiet splash". Delete these from that line and press Control+X to boot. This will show you what's happening behind the scenes (and what it's getting stuck on). So you like it and want to make the change permanent If you want to make it permanent, edit /etc/default/grub as root, delete "quiet splash" from the GRUB_CMDLINE_LINUX_DEFAULT variable, save and then run sudo update-grub

I'm not a big fan of not seeing what's going on during boot up no matter what the operating system is. Usually most operating systems will display a pretty (or ugly) splash screen to hide the craziness of loading up what's needed to get the operating system up and running. Here is how to change Ubuntu to show everything going on during boot up Temporary (this will only happen this one time so you can see if you like it) When you get to the Grub boot menu (hold left shift on boot), edit the top option by pressing e and search the boot command until you see the two words "quiet splash". Delete these from that line and press Control+X to boot. This will show you what's happening behind the scenes (and what it's getting stuck on). So you like it and want to make the change permanent If you want to make it permanent, edit /etc/default/grub as root, delete "quiet splash" from the GRUB_CMDLINE_LINUX_DEFAULT variable, save and then run sudo update-grub

If you are like many computer users, you would frequently like to make changes in various text files wherever certain patterns appear, or extract data from parts of certain lines while discarding the rest. To write a program to do this in a language such as C or Pascal is a time-consuming inconvenience that may take many lines of code. The job may be easier with awk. The awk utility interprets a special-purpose programming language that makes it possible to handle simple data-reformatting jobs easily with just a few lines of code. This manual teaches you what awk does and how you can use awk effectively. You should already be familiar with basic system commands such as ls. Using awk you can: manage small, personal databases generate reports validate data produce indexes, and perform other document preparation tasks even experiment with algorithms that can be adapted later to other computer languages This manual has the difficult task of being both tutorial and reference. If you are a novice, feel free to skip over details that seem too complex. You should also ignore the many cross references; they are for the expert user, and for the on-line Info version of the manual. nawkUS.pdf nawkUS.pdf

If you are like many computer users, you would frequently like to make changes in various text files wherever certain patterns appear, or extract data from parts of certain lines while discarding the rest. To write a program to do this in a language such as C or Pascal is a time-consuming inconvenience that may take many lines of code. The job may be easier with awk. The awk utility interprets a special-purpose programming language that makes it possible to handle simple data-reformatting jobs easily with just a few lines of code. This manual teaches you what awk does and how you can use awk effectively. You should already be familiar with basic system commands such as ls. Using awk you can: manage small, personal databases generate reports validate data produce indexes, and perform other document preparation tasks even experiment with algorithms that can be adapted later to other computer languages This manual has the difficult task of being both tutorial and reference. If you are a novice, feel free to skip over details that seem too complex. You should also ignore the many cross references; they are for the expert user, and for the on-line Info version of the manual. nawkUS.pdf nawkUS.pdf

Needed a quick reference to troubleshoot / monitor linux systems Identify CPU/Hardware dmidecode | less (shows everything in BIOS) cat /proc/cpuinfo less /proc/cpuinfo lscpu (lists available cpus) lshal (list all hardware visible by HAL) lspci (shows all PCI devices) lsusb (shows all USB devices) lsblk (shows all block devices like hardrives, cdroms) lsmod (shows installed device drivers/modules) df -h (disk space usage) du -h (estimate disk usage) cat /proc/partitions (show partitions) hdparm -i /dev/sda hwinfo hwinfo --short hwinfo | more grep processor /proc/cpuinfo | wc -l (If the load averages show that the load is increasing and is above the number of CPUs, you should look at what is causing the load. Load is a combined measure of CPU and I/O utilisation so top can be used to get real-time statistics.) vmstat 5 10 (the free column shows that the amount of free memory, The si and so columns show the amount of data being transferred between the systems swap and its memory) Network ifconfig -a ifconfig -a|less more /etc/sysconfig/network-scripts/ifcfg-eth0 route -n route (shows network route) netstat -tulpn (list of all open ports) Identify Memory cat /proc/meminfo free free -m (shows memory and swap information) free -mt free -gt Identify Kernel (Linux version) cat /proc/version uname -mrs uname -a lsb_release -a cat /etc/*release* top (display list of tasks) ps aux (display all running processes) ps aux | grep process-name rpm -qa (shows what software is installed) rpm -qa | grep 'software-name' rpm -qa | less User ulimit -a (find out user limits) ps -p $$ | tail -1 | awk '{ print $4 }' (find out user shell) tail -f /var/log/secure (view login logs) vi /var/log/secure (view login logs) grep 'something' /var/log/secure (view login logs) who (whos logged on) groups userid (shows what groups a user is a member of) note: could also do $ grep userid /etc/group lid -g groupname (shows members of a group) note: could also do $ grep '^groupname' /etc/group

Needed a quick reference to troubleshoot / monitor linux systems Identify CPU/Hardware dmidecode | less (shows everything in BIOS) cat /proc/cpuinfo less /proc/cpuinfo lscpu (lists available cpus) lshal (list all hardware visible by HAL) lspci (shows all PCI devices) lsusb (shows all USB devices) lsblk (shows all block devices like hardrives, cdroms) lsmod (shows installed device drivers/modules) df -h (disk space usage) du -h (estimate disk usage) cat /proc/partitions (show partitions) hdparm -i /dev/sda hwinfo hwinfo --short hwinfo | more grep processor /proc/cpuinfo | wc -l (If the load averages show that the load is increasing and is above the number of CPUs, you should look at what is causing the load. Load is a combined measure of CPU and I/O utilisation so top can be used to get real-time statistics.) vmstat 5 10 (the free column shows that the amount of free memory, The si and so columns show the amount of data being transferred between the systems swap and its memory) Network ifconfig -a ifconfig -a|less more /etc/sysconfig/network-scripts/ifcfg-eth0 route -n route (shows network route) netstat -tulpn (list of all open ports) Identify Memory cat /proc/meminfo free free -m (shows memory and swap information) free -mt free -gt Identify Kernel (Linux version) cat /proc/version uname -mrs uname -a lsb_release -a cat /etc/*release* top (display list of tasks) ps aux (display all running processes) ps aux | grep process-name rpm -qa (shows what software is installed) rpm -qa | grep 'software-name' rpm -qa | less User ulimit -a (find out user limits) ps -p $$ | tail -1 | awk '{ print $4 }' (find out user shell) tail -f /var/log/secure (view login logs) vi /var/log/secure (view login logs) grep 'something' /var/log/secure (view login logs) who (whos logged on) groups userid (shows what groups a user is a member of) note: could also do $ grep userid /etc/group lid -g groupname (shows members of a group) note: could also do $ grep '^groupname' /etc/group

Microsoft Outlook signatures are kept as separate files in the Signatures folder. You can find this folder in the following location; Windows XP C:Documents and Settings%username%Application DataMicrosoftSignatures Windows Vista, Windows 7 and Windows 8 C:Users%username%AppDataRoamingMicrosoftSignatures To see these folders you must have “View hidden files and folders” enabled or you can simply copy and paste the above paths in the address bar in Explorer to directly open the folder.

Microsoft Outlook signatures are kept as separate files in the Signatures folder. You can find this folder in the following location; Windows XP C:Documents and Settings%username%Application DataMicrosoftSignatures Windows Vista, Windows 7 and Windows 8 C:Users%username%AppDataRoamingMicrosoftSignatures To see these folders you must have “View hidden files and folders” enabled or you can simply copy and paste the above paths in the address bar in Explorer to directly open the folder.

Check out these programs that all work on a linux (alphabetical order) BeatForce a computer DJ system for two players with independent playlists, song databases, mixers, samplers, etc BpmDj very interesting set of programs for the Linux DJ DBMix software DJ digital audio mixing system DJ Krazy a neat MP3/CD mixer for the Linux DJ in us all... DJPlay "aims to be a high-class live DJing application for Linux" Final Scratch pro-audio computerized DJ system from Stanton Magnetics GDAM Geoff & Dave's Audio Mixer, a new mixer for the Linux digital DJ Jay'O'Rama cool DJ tool for PCM/MP3/OGG playback and manipulation Mixxx a cool DJ mixer from the Andersen brothers MP3Mixer a system for mixing multiple MPEG audio streams in realtime Oolaboola virtual turntable fun with Eric Tiedemann's "open-source cyber-shamanic noise-maker" terminatorX enables hip-hop style "scratching" of WAV files UltraMixer very cool virtual DJ mixing software, requires Java Will keep adding to this post when I get more info

Check out these programs that all work on a linux (alphabetical order) BeatForce a computer DJ system for two players with independent playlists, song databases, mixers, samplers, etc BpmDj very interesting set of programs for the Linux DJ DBMix software DJ digital audio mixing system DJ Krazy a neat MP3/CD mixer for the Linux DJ in us all... DJPlay "aims to be a high-class live DJing application for Linux" Final Scratch pro-audio computerized DJ system from Stanton Magnetics GDAM Geoff & Dave's Audio Mixer, a new mixer for the Linux digital DJ Jay'O'Rama cool DJ tool for PCM/MP3/OGG playback and manipulation Mixxx a cool DJ mixer from the Andersen brothers MP3Mixer a system for mixing multiple MPEG audio streams in realtime Oolaboola virtual turntable fun with Eric Tiedemann's "open-source cyber-shamanic noise-maker" terminatorX enables hip-hop style "scratching" of WAV files UltraMixer very cool virtual DJ mixing software, requires Java Will keep adding to this post when I get more info

Check these out... Observium Developed on Debian/Ubuntu systems but does support the RHEL/CentOS system. Requirements Apache fping MySQL Net-SNMP 5.4+ RRDtool 1.3+ Graphviz PHP 5.3+ Requirements for optional features: Ipmitool - Only if you want to poll IPMI baseboard controllers on servers Libvirt-bin - Only if you want to monitor remote VM hosts using libvirt Nagios Focused on Ubuntu system Requirements: Apache 2 PHP GCC compiler and development libraries GD development libraries Zabbix

Check these out... Observium Developed on Debian/Ubuntu systems but does support the RHEL/CentOS system. Requirements Apache fping MySQL Net-SNMP 5.4+ RRDtool 1.3+ Graphviz PHP 5.3+ Requirements for optional features: Ipmitool - Only if you want to poll IPMI baseboard controllers on servers Libvirt-bin - Only if you want to monitor remote VM hosts using libvirt Nagios Focused on Ubuntu system Requirements: Apache 2 PHP GCC compiler and development libraries GD development libraries Zabbix

Many hardware and software solutions exist to implement redundancy and load balancing for hosted services. One way to implement load balancing and redundancy is to use anycast, defined in RFC 1546. In an anycast setup, multiple hosts share the same IP address. This address is announced through a routing protocol, so that packets sent to the anycast address will be routed to the (network topology wise) closest host. A paper from Cisco provides a good background on anycast. Another, more theoretical paper is available from IBM. Because anycast relies only on a routing protocol, no additional hardware or software is needed to implement it. Since it relies on inherently dynamic routing protocols (such as OSPF or BGP) to decide which host packets are routed to, it is generally only useful for protocols that require very little state, such as DNS. According to some, in practice this instability is not significant enough to prevent anycast from being used for TCP-based services. Adds redundancy and load balancing to connectionless client/server services and improve availability and possibly latency. Anycast is a communication model (network service) for IPv4 and IPv6. As originally described in RFC 1546, "Host Anycast Service," the purpose of anycast is to assign an identical anycast address to a group of geographically distributed nodes. IP datagrams approach the nearest destination node in the set of available destination nodes, based on the unicast routing measure of distance transparent to the clients. The network (routing system) decides where to guide the client request. An IPv4 anycast address is distinguishable from a unicast address because they are allocated from a special reserved range. This is different in IPv6. The real-world applications of anycast I am aware of are limited to DNS root server concepts and Protocol Independent Multicast (PIM) rendezvous points, stateless protocols in general. Anycast is usually implemented by using Border Gateway Protocol (BGP) to simultaneously announce the same destination IP address range from many different places on the network. This results in packets addressed to destination addresses in this range being routed to the "nearest" point on the net announcing the given destination IP address. In the past, anycast was suited to connectionless protocols (generally built on UDP), rather than connection-oriented protocols such as TCP that keep their own state. However, there are many cases where TCP anycast is now used. With TCP anycast, there are cases where the receiver selected for any given source may change from time to time as optimal routes change, silently breaking any conversations that may be in progress at the time. These conditions are typically referred to as a "pop switch". To correct for this issue, there have been proprietary advancements within custom IP stacks which allow for healing of stateful protocols where it is required. For this reason, anycast is generally used as a way to provide high availability and load balancing for stateless services such as access to replicated data; for example, DNS service is a distributed service over multiple geographically dispersed servers. Unicast addressing uses a one-to-one association between destination address and network endpoint: each destination address uniquely identifies a single receiver endpoint. Multicast addressing uses a one-to-unique many association, datagrams are routed from a single sender to multiple selected endpoints simultaneously in a single transmission. Broadcast addressing uses a one-to-many association, datagrams are routed from a single sender to multiple endpoints simultaneously in a single transmission. The network automatically replicates datagrams as needed for all network segments (links) that contain an eligible receiver. Anycast addressing routes datagrams to a single member of a group of potential receivers that are all identified by the same destination address. This is a one-to-nearest association. Cisco Router Configuration ip sla 101 dns anycast.example.com name-server 10.10.10.1 frequency 30 ip sla schedule 101 life forever start-time now ! track 101 ip sla 101 ! ip route 10.0.0.1 255.255.255.255 10.10.10.1 track 101 Here is the IP route on the router: router# show ip route 10.0.0.1 Routing entry for 10.0.0.1/32 Known via "static", distance 1, metric 0 Redistributing via eigrp 1234 Advertised by eigrp 1234 route-map STATIC-TO-EIGRP bgp 1234 Routing Descriptor Blocks: * 10.10.10.1 Route metric is 0, traffic share count is 1 Then you can see that this same address is also available from multiple locations: router# show ip eigrp topology 10.0.0.1/32 EIGRP-IPv4 Topology Entry for AS(1234)/ID(10.9.9.1) for 10.0.0.1/32 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2562560 Descriptor Blocks: 10.10.10.1, from Rstatic, Send flag is 0x0 ... 10.8.8.1 (Vlan20), from 10.6.6.1, Send flag is 0x0 ... 10.7.7.1 (Vlan30), from 10.4.4.1, Send flag is 0x0 On the Unix server I have the following network interfaces setup: eth0 Link encap:Ethernet HWaddr 00:15:17:A6:25:97 inet addr:10.10.10.1 Bcast:10.10.10.255 Mask:255.255.255.0 lo:1 Link encap:Local Loopback inet addr:10.0.0.1 Mask:255.255.255.255 To summarize the whole setup. The router does a DNS query to the DNS server that is directly connected to it every 30 seconds. If the DNS query succeeds the static router stays in the table. If the test fails the route is withdrawn. If a DNS query is sent to 10.0.0.1 the router will process this by sending the query to the IP address the static route points to. The DNS server accepts the query on the management interface, then passes it to the lo:1 interface for processing. Depending on where you are at you automatically get routed to the closest server: dj@thezah:~$ traceroute 10.0.0.1 traceroute to 10.0.0.1 (10.0.0.1), 30 hops max, 60 byte packets 1 l3-core-vl7.nts.example.com (10.50.1.46) 0.309 ms 0.338 ms 0.381 ms 2 anycast.ip.example.com (10.0.0.1) 0.202 ms 0.195 ms 0.180 ms dj@hosangit:~$ sudo traceroute 10.0.0.1 traceroute to 10.0.0.1 (10.0.0.1), 64 hops max, 52 byte packets 1 nts-desk120-brook.nts.example.com (10.50.120.125) 0 ms 0 ms 0 ms 2 anycast.ip.example.com (10.0.0.1) 0 ms 0 ms 0 ms The best thing about this setup is: If a server fails you automatically fail over to the next closest server. This way the client does not have to deal with DNS times outs. Depending on your location you are automatically routed to the closest server. This will help with DNS response time. It is not that hard to setup. Nothing special is needed either the router or the server.

Many hardware and software solutions exist to implement redundancy and load balancing for hosted services. One way to implement load balancing and redundancy is to use anycast, defined in RFC 1546. In an anycast setup, multiple hosts share the same IP address. This address is announced through a routing protocol, so that packets sent to the anycast address will be routed to the (network topology wise) closest host. A paper from Cisco provides a good background on anycast. Another, more theoretical paper is available from IBM. Because anycast relies only on a routing protocol, no additional hardware or software is needed to implement it. Since it relies on inherently dynamic routing protocols (such as OSPF or BGP) to decide which host packets are routed to, it is generally only useful for protocols that require very little state, such as DNS. According to some, in practice this instability is not significant enough to prevent anycast from being used for TCP-based services. Adds redundancy and load balancing to connectionless client/server services and improve availability and possibly latency. Anycast is a communication model (network service) for IPv4 and IPv6. As originally described in RFC 1546, "Host Anycast Service," the purpose of anycast is to assign an identical anycast address to a group of geographically distributed nodes. IP datagrams approach the nearest destination node in the set of available destination nodes, based on the unicast routing measure of distance transparent to the clients. The network (routing system) decides where to guide the client request. An IPv4 anycast address is distinguishable from a unicast address because they are allocated from a special reserved range. This is different in IPv6. The real-world applications of anycast I am aware of are limited to DNS root server concepts and Protocol Independent Multicast (PIM) rendezvous points, stateless protocols in general. Anycast is usually implemented by using Border Gateway Protocol (BGP) to simultaneously announce the same destination IP address range from many different places on the network. This results in packets addressed to destination addresses in this range being routed to the "nearest" point on the net announcing the given destination IP address. In the past, anycast was suited to connectionless protocols (generally built on UDP), rather than connection-oriented protocols such as TCP that keep their own state. However, there are many cases where TCP anycast is now used. With TCP anycast, there are cases where the receiver selected for any given source may change from time to time as optimal routes change, silently breaking any conversations that may be in progress at the time. These conditions are typically referred to as a "pop switch". To correct for this issue, there have been proprietary advancements within custom IP stacks which allow for healing of stateful protocols where it is required. For this reason, anycast is generally used as a way to provide high availability and load balancing for stateless services such as access to replicated data; for example, DNS service is a distributed service over multiple geographically dispersed servers. Unicast addressing uses a one-to-one association between destination address and network endpoint: each destination address uniquely identifies a single receiver endpoint. Multicast addressing uses a one-to-unique many association, datagrams are routed from a single sender to multiple selected endpoints simultaneously in a single transmission. Broadcast addressing uses a one-to-many association, datagrams are routed from a single sender to multiple endpoints simultaneously in a single transmission. The network automatically replicates datagrams as needed for all network segments (links) that contain an eligible receiver. Anycast addressing routes datagrams to a single member of a group of potential receivers that are all identified by the same destination address. This is a one-to-nearest association. Cisco Router Configuration ip sla 101 dns anycast.example.com name-server 10.10.10.1 frequency 30 ip sla schedule 101 life forever start-time now ! track 101 ip sla 101 ! ip route 10.0.0.1 255.255.255.255 10.10.10.1 track 101 Here is the IP route on the router: router# show ip route 10.0.0.1 Routing entry for 10.0.0.1/32 Known via "static", distance 1, metric 0 Redistributing via eigrp 1234 Advertised by eigrp 1234 route-map STATIC-TO-EIGRP bgp 1234 Routing Descriptor Blocks: * 10.10.10.1 Route metric is 0, traffic share count is 1 Then you can see that this same address is also available from multiple locations: router# show ip eigrp topology 10.0.0.1/32 EIGRP-IPv4 Topology Entry for AS(1234)/ID(10.9.9.1) for 10.0.0.1/32 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2562560 Descriptor Blocks: 10.10.10.1, from Rstatic, Send flag is 0x0 ... 10.8.8.1 (Vlan20), from 10.6.6.1, Send flag is 0x0 ... 10.7.7.1 (Vlan30), from 10.4.4.1, Send flag is 0x0 On the Unix server I have the following network interfaces setup: eth0 Link encap:Ethernet HWaddr 00:15:17:A6:25:97 inet addr:10.10.10.1 Bcast:10.10.10.255 Mask:255.255.255.0 lo:1 Link encap:Local Loopback inet addr:10.0.0.1 Mask:255.255.255.255 To summarize the whole setup. The router does a DNS query to the DNS server that is directly connected to it every 30 seconds. If the DNS query succeeds the static router stays in the table. If the test fails the route is withdrawn. If a DNS query is sent to 10.0.0.1 the router will process this by sending the query to the IP address the static route points to. The DNS server accepts the query on the management interface, then passes it to the lo:1 interface for processing. Depending on where you are at you automatically get routed to the closest server: dj@thezah:~$ traceroute 10.0.0.1 traceroute to 10.0.0.1 (10.0.0.1), 30 hops max, 60 byte packets 1 l3-core-vl7.nts.example.com (10.50.1.46) 0.309 ms 0.338 ms 0.381 ms 2 anycast.ip.example.com (10.0.0.1) 0.202 ms 0.195 ms 0.180 ms dj@hosangit:~$ sudo traceroute 10.0.0.1 traceroute to 10.0.0.1 (10.0.0.1), 64 hops max, 52 byte packets 1 nts-desk120-brook.nts.example.com (10.50.120.125) 0 ms 0 ms 0 ms 2 anycast.ip.example.com (10.0.0.1) 0 ms 0 ms 0 ms The best thing about this setup is: If a server fails you automatically fail over to the next closest server. This way the client does not have to deal with DNS times outs. Depending on your location you are automatically routed to the closest server. This will help with DNS response time. It is not that hard to setup. Nothing special is needed either the router or the server.

grep is a very powerful tool that you will for sure use often. You can search through multiple files for specific strings of characters and then view the list of matching files onscreen. To find text strings with grep: grep djzah db.thezah.com At the shell prompt, type grep, the text you're trying to locate (in this case djzah), and the file you're searching in (here, db.thezah.com). grep will return all lines in the file that contain the specified string. grep -5 djzah db.thezah.com You can specify that a number of lines (say 5) on either side of the found text string should be displayed. Sometimes you can't tell what you need to know with just the line that contains your search string, and adding lines around it can help give you a context. Note: This option isn't available on all versions of grep, but it'll work for most. grep -c djzah db.thezah.com By adding the -c flag, you can find out how many times a text string appears in a file grep -v djzah db.thezah.com With the -v flag, you can find all of the lines that do not contain the specified string grep -i djzah db.thezah.com With the -i flag, you can search without case-sensitivity. Here any line with djzah or DJzah would be found. TIPS Use the -n flag (for example grep -n djzah db.thezah.com) to print each found line with a line number. You can use grep with multiple filenames, such as in grep djzah db.* To include spaces you " like grep "Serial Number" db.* To use regular expressions with grep: grep .jzah db.thezah.com Type grep followed by the regular expression and the filename. Here, we've used the regular expression .jzah to find all instances of "jzah" that are preceded by a single character. NOTE: this usage of a . to match a single character closely resembles the ? wildcard. You could also use multiple periods for specific numbers of characters. For example, to find "Dogbert" and "Dilbert" you could use grep D..bert filename

grep is a very powerful tool that you will for sure use often. You can search through multiple files for specific strings of characters and then view the list of matching files onscreen. To find text strings with grep: grep djzah db.thezah.com At the shell prompt, type grep, the text you're trying to locate (in this case djzah), and the file you're searching in (here, db.thezah.com). grep will return all lines in the file that contain the specified string. grep -5 djzah db.thezah.com You can specify that a number of lines (say 5) on either side of the found text string should be displayed. Sometimes you can't tell what you need to know with just the line that contains your search string, and adding lines around it can help give you a context. Note: This option isn't available on all versions of grep, but it'll work for most. grep -c djzah db.thezah.com By adding the -c flag, you can find out how many times a text string appears in a file grep -v djzah db.thezah.com With the -v flag, you can find all of the lines that do not contain the specified string grep -i djzah db.thezah.com With the -i flag, you can search without case-sensitivity. Here any line with djzah or DJzah would be found. TIPS Use the -n flag (for example grep -n djzah db.thezah.com) to print each found line with a line number. You can use grep with multiple filenames, such as in grep djzah db.* To include spaces you " like grep "Serial Number" db.* To use regular expressions with grep: grep .jzah db.thezah.com Type grep followed by the regular expression and the filename. Here, we've used the regular expression .jzah to find all instances of "jzah" that are preceded by a single character. NOTE: this usage of a . to match a single character closely resembles the ? wildcard. You could also use multiple periods for specific numbers of characters. For example, to find "Dogbert" and "Dilbert" you could use grep D..bert filename

You might need to use tail which displays the last lines of a file. To view file endings with tail: tail filename At the shell prompt, type fail followed by the filename. To view a specified number of lines: tail -20 filename Here, all you do is add a specific number of lines you want to view To view the endings of multiple files: tail filename* | more Pipe the tail command and the files (multiple files indicated with *) to more head and tail are great for splitting long files. Use wc -l to count the lines. If the file has 500 lines, but you care about only the beginning and ending lines, then type head -25 filename > new filename to put the first 25 lines of the file into a new file. Then do the same with tail to put the last 25 lines of the file into another new file.

You might need to use tail which displays the last lines of a file. To view file endings with tail: tail filename At the shell prompt, type fail followed by the filename. To view a specified number of lines: tail -20 filename Here, all you do is add a specific number of lines you want to view To view the endings of multiple files: tail filename* | more Pipe the tail command and the files (multiple files indicated with *) to more head and tail are great for splitting long files. Use wc -l to count the lines. If the file has 500 lines, but you care about only the beginning and ending lines, then type head -25 filename > new filename to put the first 25 lines of the file into a new file. Then do the same with tail to put the last 25 lines of the file into another new file.

Using head you can find out quickly what's in a file by viewing the top few lines. To view the beginnings with head: head filename At the shell prompt, type head followed by the filename. By default you'll see the first ten lines on the screen. To view a specified number of lines: head -20 filename Add -20 (or whatever number of lines you want to view) to view a specific number of lines To view the beginnings of multiple files: head filename* | more You can view the tops of multiple files by piping head (plus filenames) to more.

Using head you can find out quickly what's in a file by viewing the top few lines. To view the beginnings with head: head filename At the shell prompt, type head followed by the filename. By default you'll see the first ten lines on the screen. To view a specified number of lines: head -20 filename Add -20 (or whatever number of lines you want to view) to view a specific number of lines To view the beginnings of multiple files: head filename* | more You can view the tops of multiple files by piping head (plus filenames) to more.

You can use the command wc to count how many words or lines are in a file and here are some examples: To count words using wc: wc -w filename At the shell prompt, type wc -w (for words) and the name of the file in which you want to count the words. To count lines with wc: wc -l filename Use wc -l followed by the filename to count the lines. This is useful for things like lists. To count files in a directory ls | wc -l Use ls with wc to count the regular files and directories or use ls -A | wc -l to count all files and directories (except for the . and .. directories) To count bytes of a specific file wc -c filename This shows how many bytes a specific file takes up. You could use wc with no flags at all to get the lines, words and bytes of a file.