"LINUX" Port number and POW (2,n) Table

The/* linux of the lower end of the port is maintained by the IANA (internet assigned numbers authority, an internet-assigned numerical authority), and the port number is divided into 3 segments. 1, 0~1023, (10) These ports have IANA allocations and controls, and, if possible, the same port number is assigned to the same given service as TCP, UDP, and SCTP. such as the 80 port is given Web Services 2, 1024~49151, these ports are not controlled by the IANA, but registered by the IANA and provide their use list, has been convenient for the entire group. The same port number is also assigned to TCP and UDP for the same given service. such as the 6000~6003 port is assigned to the X window server for both protocols. 3, 49152~65535, (16) dynamic port. The IANA, regardless of these ports, is what we call a temporary port. (49152 This magic number is 65536 of three-fourths). */#include  <iostream>using namespace std;int main () {cout <<  "POW (2,n ) " << endl;for (int i=0,tmp=1;i<20;i++) {cout<<i<<"   "<<tmp< <endl;    tmp*=2;} return 0;} /*0 11 22 43 84 165 326 647 1288 2569 51210 102411  204812 409613 819214 1638415 3276816 6553617 13107218 26214419  524288vi /etc/services First Class http://www.linuxidc.com/linux/2007-06/4744.htm1 tcpmux tcp  Port Service Multiplexing  5 rje  Remote Job Entry  7 echo echo  Services  9 discard  NULL service for connection testing  11 systat  system state for enumerating connected ports  13 daytime  send a date and time to the requesting host  17 qotd  send the daily Maxim  18 msp  message sending protocol to the connected host  19 chargen  character generation service; send endless stream of characters  20 ftp-data FTP  data ports  21 ftp  File Transfer Protocol (FTP) port, sometimes used by File service Protocol (FSP)  22 ssh  secure  shell (SSH) service  23 telnet telnet   Services  25 smtp  Simple Mail Transfer Protocol (SMTP)  37 time  Time Protocol  39 rlp  Resource Location protocol   42 nameserver  Internet Name Services  43 nicname WHOIS  Directory services  49 tacacs  for   based tcp/ip  authentication and access to the terminal Access Controller access control system  50 re-mail-ck  Remote Mail Check protocol  53 domain  domain name services (such as   BIND)  63 whois++ whois++, extended  WHOIS  Services  67 bootps  Boot Protocol (BOOTP) service ; also used by the Dynamic Host Configuration Protocol (DHCP) service to use  68 bootpc bootstrap (BOOTP) clients, and also by Dynamic Host Configuration Protocol (DHCP) customers  69 tftp  Small File Transfer Protocol (TFTP)  70 gopher&nbsP gopher  Internet document Search and Retrieval  71 netrjs-1  remote Job Services  72 netrjs-2  Remote Job Services  73  netrjs-3  Remote Job Service  73 netrjs-4  Remote Job Services  79 finger   Finger  Services for user contact information  80 http  Hypertext Transfer Protocol (HTTP)  88 kerberos Kerberos  network authentication system for the World Wide Web (WWW) service  95  supdup Telnet  Protocol Extensions  101 hostname SRI-NIC  hostname service on the machine &NBSP;102&NBSP;ISO-TSAP  ISO  Development Environment (ISODE) network applications  105 csnet-ns  mailbox name servers, also used by  CSO  name servers  107  rtelnet  Remote  Telnet 109 pop2  Post Office Protocol version 2 110 pop3  Post Office Protocol version 3 111  sunrpc  Remote Procedure Call (RPC) protocol for Remote command execution, used by Network File system (NFS)  113 auth  Authentication and identification protocol  115 sftp  Secure File Transfer Protocol (SFTP) service  117 uucp-path Unix  to  Unix  Replication Protocol (UUCP) path service &NBSP;119&NBSP;NNTP   Network News Transfer Protocol (NNTP)  123 ntp  Network Time Protocol (NTP) for the  USENET  discussion system  137 netbios-ns   was  samb in Red Hat Enterprise  Linux  NETBIOS  Name Services used by a   138 netbios-dgm  used by  Samba  in Red Hat Enterprise  Linux   NETBIOS  Datagram Services  139 netbios-ssn  net  used by  Samba  in Red Hat Enterprise  Linux  bios  Session Services  143 imap  Internet Message Access Protocol (IMAP)  161 snmp  Simple Network Management Protocol (SNMP)  162  snmptrap snmp  Traps  163 cmip-man  General Management Information Protocol (CMIP)  164 cmip-agent  General Management Information Protocol (CMIP)  174 mailq MAILQ 177 xdmcp X  Display Manager Control Protocol  178 nextstep  NeXTStep  Windows Server  179 bgp  Boundary Network protocol  191 prospero Cliffod Neuman   Prospero  Services  194 irc  Internet Relay Chat (IRC)  199 smux SNMP UNIX  multiplexing  201 at-rtmp AppleTalk  routing  202 at-nbp AppleTalk  name binding  204  at-echo appletalk echo  Services  206 at-zis AppleTalk  block Information  209 qmtp   Fast Mail Transfer Protocol (QMTP)  210 z39.50 niso z39.50  database  213 ipx  Internetwork Packet Switching Protocol (IPX), by  Novell Netware  Common Datagram Protocol for Environment  220 imap3  Internet Message Access Protocol version 3 245 link link 347 fatserv  fatmen  Server  363 rsvp_tunnel RSVP  tunnel  369 rpc2portmap Coda  file System port mapper  370 codaauth2 Coda  File System Validation Service  372 ulistproc unix listserv 389  ldap  Lightweight Directory Access Protocol (LDAP)  427 svrloc  Service Location Protocol (SLP)  434 mobileip-agent  Removable Internet Protocol (IP) proxy  435 mobilip-mn  removable Internet Protocol (IP) Manager  443 https  Secure Hypertext Transfer Protocol (HTTP)  444  snpp  Small Network Paging protocol  445 microsoft-ds  Server Message Block (SMB)  464  through  TCP/IP  kpasswd kerberos  Password and key change service  468 photuris Photuris  session Key Management Protocol  487 saft   Simple Asymmetric file Transfer (SAFT) protocol  488 gss-http  Universal Security Services for  HTTP  (GSS)  496 pim-rp-disc   Rendezvous point Discovery for Protocol Independent Multicast (PIM) services (RP-DISC) &NBsp;500 isakmp  Internet Security Association and Key Management Protocol (ISAKMP)  535 iiop  Internet Internal Object Request Proxy Protocol (IIOP)  538  gdomap gnustep  Distributed Object Mapper (GDOMAP)  546 dhcpv6-client  Dynamic Host Configuration Protocol (DHCP) version 6 customers  547  dhcpv6-server  Dynamic Host Configuration Protocol (DHCP) version 6 service  554 rtsp  real-time Streaming Protocol (RTSP)  563 nntps  Network News Transfer Protocol (NNTPS)  565 whoami whoami 587 submission  mail message submission agent (MSA) through Secure Sockets Layer  610  npmp-local  Network Peripheral Management Protocol (NPMP) local  /  distributed queuing System (DQS)  611 npmp-gui  Network Peripheral Management Protocol (NPMP) GUI  /  Distributed Queueing System (DQS)  612 hmmp-ind HMMP  indication  / DQS 631 ipp  Internet Printing Protocol (IPP)  636 ldaps  Lightweight Directory Access Protocol via Secure Sockets Layer (LDAPS)  674 acap  application Configuration Access Protocol (ACAP)   694 ha-cluster  "Kadmin" Database Management for Heartbeat Services  749 kerberos-adm Kerberos  version 5 (v5) for clusters with high availability  750 kerberos-iv Kerberos  version 4 (v4) Services  765 webster  Network Dictionaries  767  phonebook  Network Phone book  873 rsync rsync  File Transfer service  992 telnets   telnet via Secure Sockets Layer (Telnets)  993 imaps  Internet Message Access Protocol via Secure Sockets Layer (IMAPS)  994 ircs  Internet Relay Chat via Secure Sockets Layer (IRCS)  995 pop3s  Post Office Protocol version 3 (POPS3) through Secure Sockets Layer  linux*/

Prerequisite: First you must know that the port is not independent, it is dependent on the process. When a process is turned on, its corresponding port is turned on and the process shuts down, and the port is closed. The next time a process is turned on again, the corresponding port is turned on again. Instead of purely understanding that a port is closed, you can disable a port.

1. "~$ NETSTAT-ANP" can be used to see which ports are open.

(Note: The parameter '-n ' will convert the application to port display, that is, the address of the number format, such as: nfs->2049, ftp->21, so you can open two terminals, one for each corresponding to the port number of the program)

2. The program that applies the port can then be viewed by "~$ Lsof-i: $PORT" ($PORT refers to the corresponding port number). Or you can view the file/etc/services, from which you can find the service that corresponds to the port.

(Note: Some ports cannot be found through Netstat, the more reliable method is "~$ sudo nmap-st-o localhost")

3. To close a port, you can:

1) Disable the port via the Iptables tool, such as:

"~$ sudo iptables-a input-p tcp--dport $PORT-j DROP"

"~$ sudo iptables-a output-p tcp--dport $PORT-j DROP"

2) or turn off the corresponding application, the port will naturally shut down, such as:

"~$ kill-9 pid" (PID: Process number)

such as: Through "~$ NETSTAT-ANP | grep ssh "

There is a display: TCP 0 127.0.0.1:2121 0.0.0.0:* LISTEN 7546/ssh

Then: "~$ kill-9 7546"

("~$ chkconfig" can be used to view the open state of the system service.)

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LINUX port number and POW (2,n) Table