A very cool little website I found to generate sequential number lists:
http://textmechanic.com/Generate-List-of-Numbers.html
Also generate random number lists.
Excellent Number List Generator
Category: Random UNIX Related Items
Random UNIX Related Items
Shell Script: Create Range of Numbers
for i in {1..5}; do echo $i; done
Change 1..5 to the range you want.
for i in {2..5999}; do echo $i; done
Unix Shell Script: Convert upper to lowercase text
One command magic:
tr ‘[:upper:]’ ‘[:lower:]’ < input.txt > output.txt
Common CentOS Run levels
Common services and their run levels for auto start
httpd: chkconfig –level 234 httpd on
named: chkconfig –levels 35 named on
vsftpd: chkconfig –level 234 vsftpd on
-level 234 is fairly common
CentOS: Alias IP Ranges
cd /etc/sysconfig/network-scripts
Quick and easy range of ips:
Add this file: ifcfg-eth0-range0
Contents:
IPADDR_START= 11.xxx.xxx.xxx
IPADDR_END= 11.xxx.xxx.xxx
CLONENUM_START=0
If you want to add another range:
Add this file: ifcfg-eth0-range1
IPADDR_START=10.xxx.xxx.xxx
IPADDR_END=10.xxx.xxx.xxx
CLONENUM_START=11
Pay close attention to CLONENUM_START. In the second range it must be a number higher than the amount of IPs adding in range0. For instance, lets say your range was: 10.10.10.1 -thru-> 10.10.10.10. That is 10 IPs, so your CLONENUM-START would be 11 in the second range file.
YUM repo massive update
rpm -Uhv http://apt.sw.be/redhat/el5/en/x86_64/rpmforge/RPMS//rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
http://dag.wieers.com/rpm/FAQ.php#B
Perl Single Line – Search and Replace
perl -pi -e ‘s/about news\.$/about selling advertising space\./’ file*
How many cigarette cartons can be brought into the USA?
This is first hand experience!
You can bring 1 carton of cigarettes into the USA duty free.
Each carton after that is taxed at $10 per carton and it must be paid before leaving Customs/Immigrations to your connecting flight.
The process is extremely quick and easy.
FreeBSD: Proper buildworld technique
Follow all these steps in this exact order…this is from hard-won experience!!!
1. cvsup the correct /usr/src – example cvsup files can usually be found in /root/sup. Normally we follow the security releases e.g. RELENG 6_2 rather than stable e.g. RELENG_6
2. read /usr/src/UPDATING to make sure nothing bad is going to happen.
3. rm -rf /usr/obj or weird bad shit can happen. This is #1 cause of failed installworlds.
4. check /etc/make.conf is sensible…usually it is but for a new box it won’t be.
5. mergemaster -p – otherwise installworld can fail with new users and groups, or worse it doesn’t boot.
6. make -j16 buildworld
7. check kernel config file, usually you can use the one from the previous release, not always. Using WWW here.
8. make buildkernel KERNCONF=WWW
9. make installkernel KERNCONF=WWW
10. [OPTIONAL] reboot to see if the kernel is OK. This is a 2-edged sword, because if you don’t do it, you are screwed if there is a problem with the kernel and you’ve already done installworld. If you do it, the kernel comes up incompatible with userland, and in the worst case, tcp/ip is broken!
11. make installworld
12. mergemaster – take care not to overwrite /etc/ssh/sshd_config and lock yourself out of the box!
13. reboot and pray to the FSM!
Routing Hackers To /dev/null (Blackhole)
Add: route add -host attacker_ip 127.0.0.1 -blackhole
Remove: route delete -host attacker_ip 127.0.0.1 -blackhole
The above will route all traffic from the “attacker_ip” to a blackhole.
This is useful when you see someone relentlessly attacking any daemon on your server (ssh, http, ftp, etc).
[ad#Google Adsense]