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Showing posts with the label Linux

Linux RHEL7 Firewall

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Check current setting: iptables-save Add 80 port to public rule:  #firewall-cmd --zone=public --add-port=80/tcp --permanent #firewall-cmd --reload #iptables-save|grep 80
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Linux Port Forward

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Proxy server: CentOS 6. 6 --> IP_a Backend server: windows server 2003 --> IP_b Steps: 1. Enable ip_forward vim /etc/sysctl.conf net.ipv4.ip_forward=1 sysctl -p 2. Add firewall rules: iptables -t nat -A PREROUTING -p tcp --dport 21 -j DNAT --to-destination IP_b:21 iptables -t nat -A POSTROUTING -p tcp -d IP_b --dport 21 -j SNAT --to-source IP_a iptables -t nat -A PREROUTING  -p tcp  --dport 61000:61100 -j DNAT --to IP_b:61000-61100 service iptables save 3. Comment firewall rules: vim /etc/sysconfig/iptables #-A FORWARD -j REJECT --reject-with icmp-host-prohibited 4. Restart firewall: service iptables restart
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Perl Example

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1. 安装perl,选择自己喜欢的IDE，尝试运行一个简单的小程序。例如打印Helloworld之类的。 print "Hello World"; 2. 写一个程序，计算园的周长，让它提醒用户键入半径的长度。 print "In orde to calculate perimeter, please input radius: "; chomp($radius=<STDIN>); $Perimeter=$radius * 3.14 * 2; print "The Perimeter is: $Perimeter"; 3. 写一个程序，提醒用户键入两个数字（分两行键入），然后输出两者的乘积。 print "Please input 2 number, one line one number: "; @input=<STDIN>; $a=$input[0]; $b=$input[1]; $c=$a*$b; print "The result is: $c"; 4. 写一个程序，读入一些数字（每行一个），直到文件结尾为止。然后，根据每一个数字输出如下名单中相应的人名。比方说，如果输入数字为1、2、4和2，那么输出的人名将会是fred、betty、dino和betty。 名单：fred betty barney dino wilma pebbles bamm-bamm @input=<STDIN>; chomp(@input); $i=0; while($i <= $#input) { if ($input[$i]==1)  {print "fred\n"; } elsif($input[$i]==2) {print "betty\n"; } elsif($input[$i]==3) {print "barney\n"; } elsif($input[$i]==4)  {print "dino\n"; ...
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Perl

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Perl Character 1. Easy for use 2. Can do everything 3. Run quite fast 4. Code hard for reading Perl Suitable Area 1. 90% file process; 10% others process; 2. Write CGI script; Support website CPAN:  https://search.cpan.org Install Perl 1. Download package 2. Install package 3. set path parameter by adding C:\Perl\bin; 4. create one test file test.pl with print "Hello World" 5. in command windows input: perl test.pl Integrate into Eclipse 1. install EPIC package 2. Install PadWalker package http://blog.163.com/crazy20070501@126/blog/static/12865946520121011102620418 Example $a="Hello World"; print $a; Format if (...) {...} else if (...) {...} else {...} while (...) {...} Number 1. Standard Variables including Integer / Variable / String 2. use float to save all number 3. support: +, -, *, /, %( Remainder 8%5=3 ), **( Exponentiation 2**3=8 ) 4. write Bin: 0b11111111 5. write ...
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