# /etc/init.d/sshd restart# service sshd restart# /etc/init.d/ssh restart# service ssh restart# /etc/rc.d/sshd restart# kill -HUP `cat /var/run/sshd.pid`
set -A arrayName value1 value2 value3For example, create an array called characters with three values as follows:set -A characters Mugen Jin FuuTo print first value, enter:echo ${characters[0]}To print 3rd and last value, enter:
echo ${characters[2]}To print all values, enter:
echo ${characters[@]}To count number of items in an array called characters, enter:
echo ${#characters[@]}You can use for loop as follows to iterate through all values:
for i in ${characters[@]}; do echo "Samurai Champloo character - $i"; doneSample outputs:
Samurai Champloo character - MugenYou can add two more items as follows to exiting array:
Samurai Champloo character - Jin
Samurai Champloo character - Fuu
characters[3]="Sunflower-Samurai"
characters[4]="Detective-Manzo"
#!/bin/ksh
# set array called nameservers
set -A nameservers 192.168.1.1 192.168.1.5 202.54.1.5
# print all name servers
for i in ${nameservers[@]
do
echo $i
done
crontab -u userName -l
crontab -u vivek -l
crontab -l
# less /etc/crontabcd /etc/cron.daily/
ls -l
cat filename
cd /etc/cron.hourly/
ls -l
cat filename
cd /etc/cron.weekly/
ls -l
cat filename
cd /etc/cron.monthly/
ls -l
cat filename
cd /etc/cron.d/
ls -l
cat filename
history -crm ~/.bash_historyecho 'history -c' >> ~/.bash_historyecho 'unset HISTFILE' >> ~/.bashrc
echo 'export LESSHISTFILE="-"' >> ~/.bashrc
ns1.nixcraft.in - 202.54.1.1
ns2.nixcraft.in - 203.51.2.1
# portsnap fetch update
# cd /usr/ports/dns/djbdns
# make install clean && rehash
python -VSample outputs:
Python 2.4.3
dmidecode | lessSample outputs:dmidecode 2.10Another output from my laptop:
SMBIOS 2.5 present.
45 structures occupying 1832 bytes.
Table at 0xCFF6A000.
Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
Vendor: Phoenix Technologies LTD
Version: 2.1
Release Date: 06/23/2008
Address: 0xE4F00
Runtime Size: 110848 bytes
ROM Size: 1024 kB
Characteristics:
PCI is supported
PNP is supported
BIOS is upgradeable
BIOS shadowing is allowed
ESCD support is available
Boot from CD is supported
Selectable boot is supported
EDD is supported
3.5"/2.88 MB floppy services are supported (int 13h)
ACPI is supported
USB legacy is supported
LS-120 boot is supported
ATAPI Zip drive boot is supported
BIOS boot specification is supported
Targeted content distribution is supported
sudo dmidecode | lessSample outputs:
BIOS Information
Vendor: Dell Inc.
Version: A02
Release Date: 02/03/2010
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 2112 kB
Characteristics:
ISA is supported
PCI is supported
PC Card (PCMCIA) is supported
PNP is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
3.5"/720 KB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
CGA/mono video services are supported (int 10h)
ACPI is supported
USB legacy is supported
AGP is supported
Smart battery is supported
BIOS boot specification is supported
Function key-initiated network boot is supported
Targeted content distribution is supported
BIOS Revision: 0.2
Firmware Revision: 0.2
Handle 0x0100, DMI type 1, 27 bytes
System Information
Manufacturer: Dell Inc.
Product Name: Precision M6500
Version: Not Specified
Serial Number: 55Lxxxx
UUID: 4a2yzzzeC-3500-xxx-yyy-Bzzzzyyy5y
Wake-up Type: Power Switch
SKU Number: Not Specified
Family:
# /etc/init.d/nginx restart# nginx -s reload# /usr/local/nginx/sbin/nginx -s reload
$ sudo apt-get update
$ sudp apt-get install linux-source Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
linux-source-2.6.32
Suggested packages:
libncurses-dev ncurses-dev kernel-package libqt3-dev
The following NEW packages will be installed:
linux-source linux-source-2.6.32
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 65.9MB of archives.
After this operation, 66.0MB of additional disk space will be used.
Do you want to continue [Y/n]? y
dd if=/dev/zero of=/dev/hdX bs=512 count=1OR for sata disk, use the following syntax:
dd if=/dev/zero of=/dev/sdX bs=512 count=1In this example, empty sata disk /dev/sdb, enter (you must be login as the root user):
fdisk /dev/sdb
dd if=/dev/zero of=/dev/sdb bs=512 count=1
fdisk -l /dev/sdb
shred -n 5 -vz /dev/sda
# yum install yum-security# yum list-securityLoaded plugins: rhnplugin, securityTo list all updates that are security relevant, and get a reutrn code on whether there are security updates use:
RHSA-2009:1148-1 security httpd-2.2.3-22.el5_3.2.x86_64
RHSA-2009:1148-1 security httpd-devel-2.2.3-22.el5_3.2.i386
RHSA-2009:1148-1 security httpd-manual-2.2.3-22.el5_3.2.x86_64
RHSA-2009:1148-1 security mod_ssl-1:2.2.3-22.el5_3.2.x86_64
list-security done
# yum --security check-update# yum list-security bugzillas# yum info-security RHSA-2009:1148-1Loaded plugins: rhnplugin, securityTo get an info list of the latest packages which contain fixes for Bugzilla 3595; CVE # CVE-2009-1890 and advisories RHSA-2009:1148-1, use:
===============================================================================
RHSA-2009:1148
===============================================================================
Update ID : RHSA-2009:1148-1
Release :
Type : security
Status : final
Issued : 2009-07-08 23:00:00
Bugs : 509125 - None
: 509375 - None
CVEs : CVE-2009-1890
: CVE-2009-1891
Description : Important: httpd security update \The Apache HTTP Server is a
: popular Web server. A denial of service flaw was
: found in the Apache mod_proxy module when it was
: used as a reverse proxy. A remote attacker could
: use this flaw to force a proxy process to consume
: large amounts of CPU time. (CVE-2009-1890) A
: denial of service flaw was found in the Apache
: mod_deflate module. This module continued to
: compress large files until compression was
: complete, even if the network connection that
: requested the content was closed before
: compression completed. This would cause
: mod_deflate to consume large amounts of CPU if
: mod_deflate was enabled for a large file.
: (CVE-2009-1891) All httpd users should upgrade to
: these updated packages, which contain backported
: patches to correct these issues. After installing
: the updated packages, the httpd daemon must be
: restarted for the update to take effect.
Files : mod_ssl-2.2.3-22.el5_3.2.x86_64.rpm
: httpd-devel-2.2.3-22.el5_3.2.i386.rpm
: httpd-2.2.3-22.el5_3.2.x86_64.rpm
: httpd-devel-2.2.3-22.el5_3.2.x86_64.rpm
: httpd-manual-2.2.3-22.el5_3.2.x86_64.rpm
: mod_ssl-2.2.3-22.el5_3.2.i386.rpm
: httpd-2.2.3-22.el5_3.2.i386.rpm
: httpd-manual-2.2.3-22.el5_3.2.i386.rpm
info-security done
# yum --bz 3595 --cve CVE-2009-1890 --advisory RHSA-2009:1148-1 info updates# yum update --security
# lspci# lsusb # mkdir -p /root/backup/
# mv /lib/modules/$(uname -r)/kernel/drivers/net/wireless /root/backup/
# reboot# ifconfig -aeth0 Link encap:Ethernet HWaddr 00:19:d1:2a:ba:a8Turn of wireless interfaces after identifying the same with ifdown command:
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Memory:e3180000-e31a0000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:2475 errors:0 dropped:0 overruns:0 frame:0
TX packets:2475 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:330752 (330.7 KB) TX bytes:330752 (330.7 KB)
ppp0 Link encap:Point-to-Point Protocol
inet addr:10.1.3.49 P-t-P:10.0.31.18 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1496 Metric:1
RX packets:230 errors:0 dropped:0 overruns:0 frame:0
TX packets:496 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:37976 (37.9 KB) TX bytes:47460 (47.4 KB)
wlan0 Link encap:Ethernet HWaddr 00:1e:2a:47:42:8d
inet addr:192.168.1.100 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::21e:2aff:fe47:428d/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:908222 errors:0 dropped:0 overruns:0 frame:0
TX packets:837085 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:787222721 (787.2 MB) TX bytes:322049568 (322.0 MB)
Interrupt:18 Memory:e3000000-e3010000
# ifdown interface
# ifdown wlan0# mv /etc/sysconfig/network-scripts/ifcfg-wlan0 /root/backup# rm /etc/sysconfig/network-scripts/ifcfg-wlan0# mv /root/backup/ifcfg-wlan0 /etc/sysconfig/network-scripts/ifcfg-wlan0
# mv /root/backup/wireless /lib/modules/$(uname -r)/kernel/drivers/net/wireless
# rebootroute -nKernel IP routing table192.168.1.2 is my ISP router i.e. default gateway indicated by 0.0.0.0. Other destination such as 10.0.0.0/8 network use ppp0 interface as gateway. If you are MS-Windows user use route print command.
Destination Gateway Genmask Flags Metric Ref Use Iface
10.0.31.18 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0
38.96.196.94 192.168.1.2 255.255.255.255 UGH 0 0 0 wlan0
192.168.84.0 0.0.0.0 255.255.255.0 U 0 0 0 vmnet8
192.168.1.0 0.0.0.0 255.255.255.0 U 2 0 0 wlan0
192.168.110.0 0.0.0.0 255.255.255.0 U 0 0 0 vmnet1
192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 wlan0
10.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 ppp0
0.0.0.0 192.168.1.2 0.0.0.0 UG 0 0 0 wlan0
The DHCP client network configuration script is invoked from time to timeby dhclient. This script is used by the DHCP client to set each interface's initial configuration prior to requesting an address, to test the address once it has been offered, and to set the interface's final configuration once a lease has been acquired. If no lease is acquired, the script is used to test predefined leases, if any, and also called once if no valid lease can be identified.Update your /etc/rc.conf as follows:
hostname=""Create a file called /etc/dhclient-enter-hooks using a text editor:# vi /etc/dhclient-enter-hooks#!/bin/shSave and close the file. Set permission:
check_hostname(){
hostname laptop.nixcraft.in
}
# chmod +x /etc/dhclient-enter-hooks# dhclient ifacetimeout 60;See dhclient, dhclient.conf and dhclient-script man page for more information.
retry 60;
reboot 10;
select-timeout 5;
initial-interval 2;
interface "ep0" {
send host-name "laptop.nixcraft.in";
send dhcp-client-identifier 1:0:a0:24:ab:fb:9c;
send dhcp-lease-time 3600;
supersede domain-name "nixcraft.net.in r.nixcraft.com r.vsnl.nixcraft.net.in";
prepend domain-name-servers 127.0.0.1;
request subnet-mask, broadcast-address, time-offset, routers,
domain-name, domain-name-servers, host-name;
require subnet-mask, domain-name-servers;
script "/etc/dhclient-script";
media "media 10baseT/UTP", "media 10base2/BNC";
}
alias {
interface "ep0";
fixed-address 192.5.5.213;
option subnet-mask 255.255.255.255;
}
while [ condition ]
do
command1
command2
commandN
done
while [[ condition ]] ; docsh while loop syntax:
command1
command1
commandN
done
while ( condition )
commands
end
#!/bin/bash
c=1
while [ $c -le 5 ]
do
echo "Welcone $c times"
(( c++ ))
done
#!/bin/ksh
c=1
while [[ $c -le 5 ]]; do
echo "Welcome $c times"
(( c++ ))
done
#!/bin/cshAnother example:
c=1
while ( $c <= 5 )
echo "Welcome $c times"
@ c = $c + 1
end
#!/bin/csh
set yname="foo"
while ( $yname != "" )
echo -n "Enter your name : "
set yname = $<
if ( $yname != "" ) then
echo "Hi, $yname"
endif
end
sudo apachectl stopORsudo apachectl -k stopTo start Apache web server again, enter:sudo apachectl startORsudo apachectl -k startThe following will restart apache web server, enter:sudo apachectl restartORsudo apachectl -k restartYou can displays a brief status report by visiting the url http://localhost:80/server-status in the web browser of your choice.
sudo apachectl -k restartSample session:
sudo apachectl -k stopsudo apachectl -k start
vech='car bus bike rail airplane'
[[ $vech = *car* ]] && echo "Car found in \$vech" || echo "Sorry"You can also use the following syntax:
You can use grep to display matching pattern only:
case "$vech" in
*car*) echo "Car found, do something" ;;
*bus*) echo "call bus()";;
*) echo "Error..."
esac
grep -o "car" <<<"$vech"echo "$vech" | grep -o "car"
# rm /etc/cron.deny /etc/at.deny# vi /etc/cron.allow# vi /etc/at.allowvivekNote that even if a user called jerry is not listed in cron.allow, cron jobs, he can still be run as that user. The cron.allow file controls only administrative access to the crontab command for scheduling and modifying cron jobs. In other words you can set / modify cron jobs on behalf of jerry. Jerry can only run it but cannot set or modify jobs.
shri
krish
tom
root
foo
bar
php
# vi /etc/inittabid:5:initdefault:Replace with:id:3:initdefault:Save and close the file. Restart the server. You can also drop to text mode by typing init command:# init 3# yum groupremove "X Window System"lsof -iSample outputs:
lsof -i | less
lsof -i | grep :http
httpd 17074 dc22 4u IPv4 42496401 TCP 10.8.4.229:http (LISTEN)Where,
httpd 17230 vivek 4u IPv4 42499206 TCP 10.8.4.230:http (LISTEN)
httpd 17336 jail2 5u IPv4 42499357 TCP 10.8.4.228:https (LISTEN)
httpd 31723 phpcgi1 4u IPv4 52573816 TCP 10.8.4.227:http (LISTEN)
egrep -iw --color=auto 'user|group' /etc/httpd/conf/httpd.confSample oututs:
egrep -iw --color=auto '^user|^group' /etc/httpd/conf/httpd.conf
User apache
Group apache
# vi /etc/rc.conf ipv6_ifconfig_em0="2001:48c8:7::2 prefix 64"Save and close the file. Restart networking. You can also set it at the shell prompt using the ifconfig command as follows:
ifconfig interFace inet6 ipv6IpAddress prefixlen ValueWhere,
ifconfig fxp0 inet6 2001:48c8:7::2 prefixlen 64
$ dmesg | lessless /var/log/boot.log
less /var/log/dmesg
grep error /var/log/dmesg
grep something /var/log/boot.log
# vi /etc/sysconfig/sendmailDAEMON=noSave and close the file. Setting DAEMON=no tells Sendmail to execute only the queue runner on this machine, and never to receive SMTP mail requests on port # 25.
# vi /etc/mail/submit.cfD{MTAHost}mail.nixcraft.netSave and close the file. mail.nixcraft.net is the hostname of the server to which this machine should forward its all outgoing mail. Please note that mail.nixcraft.net must be configured to accept mail from your other workstations or server. Once done reload sendmail.
output=$1 # either text or htmlHowever, sometime user forget to pass the parameter to my shell script and my enter logic fails. So how do I set default value to text, if no parameter passed?
output=${1-text}OR (see my comment below):
echo $output
output=${1:-text}Try another example at a shell prompt:
echo $output
$ vech=Bus
$ echo ${vech-Car}
$ echo ${vech:-Car}
$ unset vech
$ echo ${vech-Car}
$ echo ${vech:-Car}#!/bin/bashNow, run it as follows:
output=${1-text}
echo "Setting output to $output..."
$ ./script.sh html
$ ./script.sh text
$ ./script.sh #!/bin/bash
output=${1-text}
[ $# -eq 0 ] && { echo "Usage: $0 format" ; exit 1; }
echo "Setting output to $output..."
host www.cyberciti.biznslookup www.cyberciti.bizwww.cyberciti.biz has address 74.86.48.9974.86.48.99 is IPv4 address and 2607:f0d0:1002:11::4 is IPv6 address for www.cyberciti.biz hostname.
www.cyberciti.biz has IPv6 address 2607:f0d0:1002:11::4
$ whois 74.86.48.99OrgName: SoftLayer Technologies Inc.
OrgID: SOFTL
Address: 1950 N Stemmons Freeway
City: Dallas
StateProv: TX
PostalCode: 75207
Country: US
ReferralServer: rwhois://rwhois.softlayer.com:4321
NetRange: 74.86.0.0 - 74.86.255.255
CIDR: 74.86.0.0/16
OriginAS: AS36351
NetName: SOFTLAYER-4-4
NetHandle: NET-74-86-0-0-1
Parent: NET-74-0-0-0-0
NetType: Direct Allocation
NameServer: NS1.SOFTLAYER.COM
NameServer: NS2.SOFTLAYER.COM
Comment: abuse@softlayer.com
RegDate: 2007-05-16
Updated: 2007-11-14
RAbuseHandle: ABUSE1025-ARIN
RAbuseName: Abuse
RAbusePhone: +1-214-442-0605
RAbuseEmail: abuse@softlayer.com
RNOCHandle: IPADM258-ARIN
RNOCName: IP Admin
RNOCPhone: +1-214-442-0600
RNOCEmail: ipadmin@softlayer.com
RTechHandle: IPADM258-ARIN
RTechName: IP Admin
RTechPhone: +1-214-442-0600
RTechEmail: ipadmin@softlayer.com
OrgAbuseHandle: ABUSE1025-ARIN
OrgAbuseName: Abuse
OrgAbusePhone: +1-214-442-0605
OrgAbuseEmail: abuse@softlayer.com
OrgTechHandle: IPADM258-ARIN
OrgTechName: IP Admin
OrgTechPhone: +1-214-442-0600
OrgTechEmail: ipadmin@softlayer.com
# ARIN WHOIS database, last updated 2009-07-23 20:00
# Enter ? for additional hints on searching ARIN's WHOIS database.
Found a referral to rwhois.softlayer.com:4321.
%rwhois V-1.5:003fff:00 rwhois.softlayer.com (by Network Solutions, Inc. V-1.5.9.5)
network:Class-Name:network
network:ID:NETBLK-SOFTLAYER.74.86.32.0/19
network:Auth-Area:74.86.32.0/19
network:Network-Name:SOFTLAYER-74.86.32.0
network:IP-Network:74.86.48.96/29
network:IP-Network-Block:74.86.48.96-74.86.48.103
network:Organization;I:SoftLayer Technologies, Inc.
network:Street-Address:1950 Stemmons Freeway Suite 2043
network:City:Dallas
network:State:TX
network:Postal-Code:75207
network:Country-Code:US
network:Tech-Contact;I:sysadmins@softlayer.com
network:Abuse-Contact;I:abuse@softlayer.com
network:Admin-Contact;I:IPADM258-ARIN
network:Created:20070708
network:Updated:20071205
network:Updated-By:ipadmin@softlayer.com
%referral rwhois://root.rwhois.net:4321/auth-area=.
%ok
$ cd /home/httpd/wiki/maintenancephp changePassword.php --user=YOUR-USERNAME-HERE --password=YOUR-PASSWORD-HERESample outputs:
# reset a password for Vivek user
php changePassword.php --user=Vivek --password=myPassowrd
Password set for VivekNow you user Vivek can login without any problem.
# yum install mrtg net-snmp net-snmp-utils# vi /etc/snmp/snmpd.confcom2sec local localhost publicSave and close the file. Restart snmpd:
group MyRWGroup v1 local
group MyRWGroup v2c local
group MyRWGroup usm local
view all included .1 80
access MyRWGroup "" any noauth exact all all none
syslocation VSNL, India
syscontact Root <vivek@nixcraft.tld>
# chkconfig snmpd on
# service snmpd restart# snmpwalk -v 1 -c public localhost IP-MIB::ipAdEntIfIndexIP-MIB::ipAdEntIfIndex.123.xx.yy.zzz = INTEGER: 2
IP-MIB::ipAdEntIfIndex.127.0.0.1 = INTEGER: 1
# cfgmaker --global 'WorkDir: /var/www/mrtg' --output /etc/mrtg/mrtg.cfg public@localhost# indexmaker --output=/var/www/mrtg/index.html /etc/mrtg/mrtg.cfg# cat /etc/cron.d/mrtg*/5 * * * * root LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg --lock-file /var/lock/mrtg/mrtg_l --confcache-file /var/lib/mrtg/mrtg.okJust make sure crond is running and you are done with configuration:
# chkconfig --list crond# chkconfig crond on
# service crond on# yum install httpd
# chkconfig httpd on
# service httpd onhttp://your-ip.add.ress/mrtg/http://192.168.1.5/mrtg/
# cfgmaker --global 'WorkDir: /var/www/mrtg' --output /etc/mrtg/mrtg.cfg public@router# cfgmaker --global 'WorkDir: /var/www/mrtg' --output /etc/mrtg/mrtg.cfg public@192.168.1.254
# netstat -tulp | grep vnc# vi /etc/sysconfig/iptables# Open VNC for USER1Save and close the file. Restart iptables:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 5800 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 5900 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 6000 -j ACCEPT
# Open VNC for USER2
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 5801 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 5901 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 6001 -j ACCEPT
# service iptables restart$IPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 5801 -j ACCEPT
$IPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 5901 -j ACCEPT
$IPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 6001 -j ACCEPT
[<transport-specifier>:]<transport-address>
127.0.0.1:161 listen on UDP port 161, but only on the loopback interface. This prevents snmpd being queried remotely. The
port specification ":161" is not strictly necessary since that is the default SNMP port.
TCP:1161 listen on TCP port 1161 on all IPv4 interfaces.
ipx:/40000 listen on IPX port 40000 on all IPX interfaces.
unix:/tmp/local-agent listen on the Unix domain socket /tmp/local-agent.
/tmp/local-agent is identical to the previous specification, since the Unix domain is assumed if the first character of the
is '/'.
PVC:161 listen on the AAL5 permanent virtual circuit with VPI=0 and VCI=161 (decimal) on the first ATM adapter in the
machine.
udp6:10161 listen on port 10161 on all IPv6 interfaces.
# vi /etc/sysconfig/snmpd.optionsOPTIONS="-Lsd -Lf /dev/null -p /var/run/snmpd.pid -a -x 127.0.0.1 192.168.1.254"Save and close the file. Reload the changes:
# service snmpd reload# vi /etc/sysconfig/iptables-A RH-Firewall-1-INPUT -p udp s 192.168.1.0/24 -m udp --dport 161 -j ACCEPTFinally, restart iptables service:
# service iptables restartServer: Dual Core CPU with Software RAID1 and 2GB RAM
eth0: Public IP 123.1.2.3
venet0: venet used by OpenVZ to talk with rest of the LAN or Internet.
Hostname: hostnode01.nixcraft.in.
vps.nixcraft.net: 123.1.2.5 - can run any supported Linux distribution.
| Beancounter value | Usage |
|---|---|
| lockedpages | The memory not allowed to be swapped out (locked with the mlock() system call), in pages. |
| shmpages | The total size of shared memory (including IPC, shared anonymous mappings and tmpfs objects) allocated by the processes of a particular VPS, in pages. |
| privvmpages | The size of private (or potentially private) memory allocated by an application. The memory that is always shared among different applications is not included in this resource parameter. |
| numfile | The number of files opened by all VPS processes. |
| numflock | The number of file locks created by all VPS processes. |
| numpty | The number of pseudo-terminals, such as an ssh session, the screen or xterm applications, etc. |
| numsiginfo | The number of siginfo structures (essentially, this parameter limits the size of the signal delivery queue). |
| dcachesize | The total size of dentry and inode structures locked in the memory. |
| physpages | The total size of RAM used by the VPS processes. This is an accounting-only parameter currently. It shows the usage of RAM by the VPS. For the memory pages used by several different VPSs (mappings of shared libraries, for example), only the corresponding fraction of a page is charged to each VPS. The sum of the physpages usage for all VPSs corresponds to the total number of pages used in the system by all the accounted users. |
| numiptent | The number of IP packet filtering entries. |
Do not take source code you did not write and try to sell it as your own software, period.I'm not a lawyer but above is simple rule to follow. Please see the following resource for more information:
# vi /etc/pf.conf# the lists of known FTPD attackersAbove will block FTP connections more than 5 times in 40 seconds. Also append the following line to /etc/rc.shutdown to keep changes after the reboot:
table <ftp-attacks> persist file "/etc/pf.ftp.block.list"
# block all incoming connections from attackers on FTPD
block in quick on $ext_if from <ftp-attacks>
# Let us allow FTP with bruteforce protection
pass in quick on $ext_if inet proto tcp from any to ($ext_if) port 21 keep state (max-src-conn-rate 5/40, overload <ftp-attacks> flush global)
# echo '/sbin/pfctl -t ftp-attacks -T show > /etc/pf.ftp.block.list' >> /etc/rc.shutdown# /etc/rc.d/pf reload# pfctl -t ftp-attacks -T show
# df -P /# df -P /usrFilesystem 512-blocks Used Avail Capacity Mounted onYou can now simply grep /usr file system and print out used capacity:
/dev/aacd0s1e 162491344 21988048 127503992 15% /usr
# df -P /usr | grep /usr | awk '{ print $5}' | sed 's/%//g'# output=$(df -P /usr | grep /usr | awk '{ print $5}' | sed 's/%//g')
# echo $output# output=($(df -P /))
# echo "${output[11]}"#!/bin/bashYou need to modify syntax, if you are using KSH or TCSH / CSH instead of BASH. Save this script and run as a cron job:
# Tested Under FreeBSD and OS X
FS="/usr"
THRESHOLD=90
OUTPUT=($(LC_ALL=C df -P ${FS}))
CURRENT=$(echo ${OUTPUT[11]} | sed 's/%//')
[ $CURRENT -gt $THRESHOLD ] && echo "$FS file system usage $CURRENT" | mail -s "$FS file system" you@example.com
@daily /path/to/your.df.script.sh#!/bin/bash
# Tested Under FreeBSD and OS X
FS="/usr"
THRESHOLD=90
OUTPUT=($(LC_ALL=C df -P ${FS}))
CURRENT=$(echo ${OUTPUT[11]} | sed 's/%//')
[ $CURRENT -gt $THRESHOLD ] && /usr/bin/zenity --warning --text="The disk $FS ($CURRENT% used) is almost full. Delete some files or add a new disk." --title="df Warning"
36 19 * * * DISPLAY=:0.0 /path/to/script.sh
# apt-get install gimp
# apt-get install krita