Wednesday, 24 August 2016

[CentOS] Setup Mail server (메일 서버 구축)

MTA (Mail Transfer Agent)
ex) Sendmail, Qmail, Microsfot Exchange

MUA (Mail user Agent)
ex) Outlook Express

MDA (Mail Delivery Agent)
ex) POP3, IMAP




Send Protocol
SMTP (Simple Mail Transfer Protocol)
 : TCP/IP mail transfer protocol. Default port 25.


1. Install Sendmail packages

# yum -y install sendmail*












2. Configure SMTP

# vi /etc/mail/sendmail.mc

Remove 'dnl' command





# m4 /etc/mail/sendmail.mc > /ect/mail/sendmail.cf
# vi /etc/mail/snedmail.cf


Cwlocalhost ->Cw[MAIL_SERVER_DOMAIL]




127.0.0.1 (Internal Mail Server) -> 0.0.0.0


3. Configure Mail Access

# vi /ect/mail/access





# makemap hash /etc/mail/access < /etc/mail/access


# vi /etc/mail/local-host-names



4. SASL security module

# service saslauthd start
# chkconfig saslauthd on
# init 6


5. Disable Firewall

# service iptables stop
# chkconfig --level 345 iptables off
# vi /etc/selinux/config
# getenforce

# service iptables status



















6. Install Dovecot packages

# yum -y install dovecot







7. Configure Dovecot

# vi /etc/dovecot/dovecot.conf






# vi /etc/dovecot/conf.d/10-mail.conf








# vi /etc/dovecot/conf.d/10-ssl.conf






# vi /etc/dovecot/conf.d/10-auth.conf





8. Start Dovecot

# service dovecot start
# chkconfig dovecot on




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[Java] Convert Hexadeciamal to IP address 

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public static String convertHex2IP( String hex) throws UnknownHostException {
 java.net.InetAddress address = java.net.InetAddress.getByAddress( javax.xml.bind.DatatypeConverter.parseHexBinary( hex));
 return address.getHostAddress();
  
}
 
public static String convertIP2Hex( String ip) throws UnknownHostException {
 java.net.InetAddress address = java.net.InetAddress.getByName( ip);
 byte[] bytes = address.getAddress();
 StringBuilder sb = new StringBuilder();
 for ( int ll = 0; ll < bytes.length; ll++)
  sb.append( String.format( "%02X", bytes[ ll]));
 
 return sb.toString();
  
}


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[Java] How to ping IP address in java (자바에서 Ping 구현) 

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public static boolean ping( String host, int milisecondTimeout) throws UnknownHostException, IOException {
  java.net.InetAddress address = InetAddress.getByName( host);
  return address.isReachable( milisecondTimeout);
  
}
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Friday, 19 August 2016

[RCP] java.lang.ClassCastException: org.eclipse.nebula.widgets.pshelf.PShelf cannot be cast to org.eclise.nebula.widgets.pshelf.PShelf in WindowBuilder when using Nebula PShelf Widget



It seems that the CSS engine sees that it can load the styled widget. Do uninstall pshelf.css feature and plugin.
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Wednesday, 17 August 2016

[Windows] How to find domain name from IP address (IP주소를 이용하여 도메인 찾기) 

> nslookup [DOMAIN]




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Tuesday, 16 August 2016

[RCP] How to remove unnecessary unnecessarypreference pages (불필요 Preference Page 제거)



If you want to remove unnecessary preference pages(Maven and Mylyn),

add commands in postWindowOpen() method which is in ApplicationWorkbenchWindowAdvisor class.


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    @Override
    public void postWindowOpen() {
     ...
     
     PreferenceManager pm = PlatformUI.getWorkbench().getPreferenceManager();
     // For checking preference nodes id
//     org.eclipse.jface.preference.IPreferenceNode[] nodes = pm.getRootSubNodes();
//     for ( int ll = 0; ll < nodes.length; ll++) {
//      System.out.println( nodes[ ll].getId());
//     }
     pm.remove( "org.eclipse.m2e.core.preferences.Maven2PreferencePage");
     pm.remove( "org.eclipse.mylyn.preferencePages.Mylyn");
     
     
 }

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Friday, 12 August 2016

[Oracle] ORA-28001: the password has expired (Unlock user has expired password)



If you try to log in invalid password  continuously, the user is locked. This is a solution that unlock user.


$> sqlplus / as sysdba


ALTER USER [USER_NAME] ACCOUNT UNLOCK;


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[Oracle] ORA-00845 : MEMORY TARGET not supported on this system2

I used Oracle 11g in CentOS VM image. this image is allocated 16GB memory. But after reducing memory to 8GB, oracle instance was not started.




1. Create pfile from spfile

cd $ORACLE_HOME/dbs

sqlplus / as sysdba


CREATE pfile='[PFILE_NAME]' from spfile='[SPFILE_NAME]'





2. Edit pfile

$> vi myinit.ora



3. Startup as pfile

$> sqlplus / as sysdba


startup pfile='[PFILE_NAME]';




4. Create sfpile from pfile

create spfile'spfile[INSTANCE_NAME].ora' from pfile'[PFILE_NAME]';


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[JSON] How to skip serialize/deserialize variables using jackson annotation 

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public class JacksonTest {
 
 private String name = null;
 private int age = 0;
 private String[] emails = null;
 private java.util.List< String> favorites = null;
 private String mobile = null;
 private java.util.concurrent.BlockingQueue< String> concurrentQueue = null;
 
 public JacksonTest() {
 }
 
 public JacksonTest( String name, int age, String[] emails, java.util.List< String> favorites, String mobile) {
  this.name = name;
  this.age = age;
  this.emails = emails;
  this.favorites = favorites;
  this.mobile = mobile;
  
 }
 
 public String getName() {
  return name;
 }
 
 public int getAge() {
  return age;
 }
 
 public String[] getEmails() {
  return this.emails;
 }

 public void setEmails(String[] emails) {
  this.emails = emails;
 }
 

 public java.util.List<String> getFavorites() {
  return this.favorites;
 }

 public void setFavorites(java.util.List<String> favorites) {
  this.favorites = favorites;
 }
 

 public String getMobile() {
  return this.mobile;
 }

 public void setMobile(String mobile) {
  this.mobile = mobile;
 }
 

 public void setName(String name) {
  this.name = name;
 }
 

 public void setAge(int age) {
  this.age = age;
 }
 
 public void setConcurrentQueue( java.util.concurrent.BlockingQueue< String> concurrentQueue) {
  this.concurrentQueue = concurrentQueue;
 }
 
 public java.util.concurrent.BlockingQueue< String> getConcurrentQueue() {
  return this.concurrentQueue;
  
 }

 public static void main(String[] args) throws IOException {
  JacksonTest jackson = new JacksonTest( "dorbae", 27, new String[] { "jangsb89@gamil.com", "dorbae@nate.com"}, null, null );
  java.util.List< String> favorites = new java.util.ArrayList< String>();
  favorites.add( "programming");
  favorites.add( "data analytics");
  favorites.add( "data modeling");
  favorites.add( "swimming");
  jackson.setFavorites( favorites);
  
  JacksonTest jackson2 = null;
  
  // Object -> JSON
  com.fasterxml.jackson.databind.ObjectMapper mapper = new com.fasterxml.jackson.databind.ObjectMapper();
  String json = mapper.writeValueAsString( jackson);
  System.out.println( "======== Object -> JSON ========");
  System.out.printf( "%s\n\n", json);
  
  // JSON -> Object
  mapper = new ObjectMapper();
  jackson2 = mapper.readValue( json, JacksonTest.class);
  System.out.println( "======== JSON -> Object ========");
  System.out.printf( "name=%s, age=%d\n", jackson2.getName(), jackson2.getAge());
  
 }

}









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    @JsonIgnore
 public void setConcurrentQueue( java.util.concurrent.BlockingQueue< String> concurrentQueue) {
  this.concurrentQueue = concurrentQueue;
 }
 
 @JsonIgnore
 public java.util.concurrent.BlockingQueue< String> getConcurrentQueue() {
  return this.concurrentQueue;
  
 }
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[JSON] Convert object to json and convert json to object using Jackson 

public class JacksonTest {
 
 private String name = null;
 private int age = 0;
 private String[] emails = null;
 private java.util.List< String> favorites = null;
 private String mobile = null;
 
 public JacksonTest() {
 }
 
 public JacksonTest( String name, int age, String[] emails, java.util.List< String> favorites, String mobile) {
  this.name = name;
  this.age = age;
  this.emails = emails;
  this.favorites = favorites;
  this.mobile = mobile;
  
 }
 
 public String getName() {
  return name;
 }
 
 public int getAge() {
  return age;
 }
 
 public String[] getEmails() {
  return this.emails;
 }

 public void setEmails(String[] emails) {
  this.emails = emails;
 }
 

 public java.util.List<String> getFavorites() {
  return this.favorites;
 }

 public void setFavorites(java.util.List<String> favorites) {
  this.favorites = favorites;
 }
 

 public String getMobile() {
  return this.mobile;
 }

 public void setMobile(String mobile) {
  this.mobile = mobile;
 }
 

 public void setName(String name) {
  this.name = name;
 }
 

 public void setAge(int age) {
  this.age = age;
 }
 

 public static void main(String[] args) throws IOException {
  JacksonTest jackson = new JacksonTest( "dorbae", 27, new String[] { "jangsb89@gamil.com", "dorbae@nate.com"}, null, null );
  java.util.List< String> favorites = new java.util.ArrayList< String>();
  favorites.add( "programming");
  favorites.add( "data analytics");
  favorites.add( "data modeling");
  favorites.add( "swimming");
  jackson.setFavorites( favorites);
  
  JacksonTest jackson2 = null;
  
  // Object -> JSON
  com.fasterxml.jackson.databind.ObjectMapper mapper = new com.fasterxml.jackson.databind.ObjectMapper();
  String json = mapper.writeValueAsString( jackson);
  System.out.println( "======== Object -> JSON ========");
  System.out.printf( "%s\n\n", json);
  
  // JSON -> Object
  mapper = new ObjectMapper();
  jackson2 = mapper.readValue( json, JacksonTest.class);
  System.out.println( "======== JSON -> Object ========");
  System.out.printf( "name=%s, age=%d\n", jackson2.getName(), jackson2.getAge());
  
 }

}

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Wednesday, 3 August 2016

[Java] How to make Concurrent Hash Set

Upper Java 1.8

java.util.Set< String> concurrentSet = java.util.concurrent.ConcurrentHashMap.newKeySet();

Lower Java 1.8

java.util.Set< String> concurrentSet = java.util.Collections.newSetFromMap( new java.util.concurrent.ConcurrentHashMap< String, Boolean>());













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[DBMS] Table schema meta table (DBMS별 테이블 스키마 테이블)














DBMSTABLE


H2INFORMATION>SCHEMA.TABLES


DerbyDBSYS.SYSTABLES


JavaDBSYS.SYSTABLES


MySQLinformation_schema.TABLES


MariaDBinformation_schema.TABLES


OracleSYS.ALL_TABLES







H2





COLUMNDATA_TYPE


TABLE_CATALOGVARCHAR


TABLE_SCHEMAVARCHAR


TABLE_NAMEVARCHAR


TABLE_TYPEVARCHAR


STORAGE_TYPEVARCHAR


SQLVARCHAR


REMARKSVARCHAR


LAST_MODIFICATIONBIGINT


IDINTEGER


TYPE_NAMEVARCHAR


TABLE_CLASSVARCHAR







MySQL(MariaDB)





COLUMNDATA_TYPE


TABLE_CATALOGVARCHAR(512)


TABLE_SCHEMAVARCHAR(64)


TABLE_NAMEVARCHAR(64)


TABLE_TYPEVARCHAR(64)


ENGINEVARCHAR(64)


VERSIONBIGINT(21) unsigned


ROW_FORMATVARCHAR(10)


TABLE_ROWSBIGINT(21) unsigned


AVG_ROW_LENGTHBIGINT(21) unsigned


DATA_LENGTHBIGINT(21) unsigned


MAX_DATA_LENGTHBIGINT(21) unsigned


INDEX_LENGTHBIGINT(21) unsigned


DATA_FREEBIGINT(21) unsigned


AUTO_INCREMENTBIGINT(21) unsigned


CREATE_TIMEdatetime


UPDATE_TIMEdatetime


CHECK_TIMEdatetime


TABLE_COLLATIONVARCHAR(32)


CHECKSUMBIGINT(21) unsigned


CREATE_OPTIONSVARCHAR(255)


TABLE_COMMENTVARCHAR(2048)












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[H2] How to run in server mode (H2 서버모드로 구동)













java -jar h2*.jar -webAllowOthers -tcpAllowOthers













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