By the port number, it can be divided into three categories: (1) Well Known Ports: From 0 to 1023, they are tightly bound to some services. Usually the communication of these ports clearly indicates the protocol of a certain service. For example: port 80 is actually always HTTP communication. (2) Registered Ports: From 1024 to 49151. They are loosely tied to some services. This means that there are many services that are bound to these ports, and these ports are also used for many other purposes. For example, many systems handle dynamic ports starting around 1024. (3) Dynamic and/or Private Ports: from 49152 to 65535. In theory, these ports should not be assigned to services. In fact, machines typically allocate dynamic ports from 1024. But there are exceptions: SUN's RPC port starts at 32768. 0 is usually used to analyze operating system
. This method works because in some systems, 0” is an invalid port, and when you try to connect to it using a normal closed port, it will produce different results. A typical scan: use the IP address of 0.0.0.0, set the ACK bit and broadcast it at the Ethernet layer. 1 tcpmux TCP Port Service Multiplexer Transmission Control Protocol Port Service Multiplexer Selector 2 compressnet Management Utility compressnet Management Utility 3 Compressnet Compression Process Compression Process 5 rje Remote Job Entry Remote Job Login 7 Echo Echo Echo 9 Discard Discard Discard 11 systat Active Users Online User 13 daytime Daytime Time 17 qotd Quote of the Day Daily Reference 18 msp Message Send Protocol Message Delivery Protocol 19 chargen Character Generator Character Generator 20 ftp-data File Transfer[Default Data] File Transfer Protocol (default data port) 21 Ftp File Transfer[Control] File Transfer Protocol (Control) 22 ssh SSH Remote Login Protocol SSH Remote Login Protocol 23 telnet Telnet Terminal Emulation Protocol 24 any private mail system Reserved for personal mail system 25 smtp Simple Mail T Ransfer Simple Mailing Protocol 27 nsw-fe NSW User System FE NSW User System Field Engineer 29 msg-icp MSG ICP MSG ICP 31 msg-auth MSG Authentication MSG Verification 33 dsp Display Support Protocol Display Support Protocol 35 any private printer server Reserved for Personal Printer Service 37 time Time Time 38 rap Route Access Protocol Route Access Protocol 39 rlp Resource Location Protocol Resource Mapping Protocol 41 graphics Graphics Graphic 42 nameserver WINS Host Name Server WINS Host Name Service 43 nicname Who Is "绰号" who is Service 44 Mpm-flags MPM FLAGS Protocol MPM (message processing module) flag protocol 45 mpm Message Processing Module [recv] message processing module 46 mpm-snd MPM [default send] message processing module (default send port) 47 ni-ftp NI FTP NI FTP 48 auditd Digital Audit Daemon number Audio background service 49 tacacs Login Host Protocol (TACACS) TACACS login host protocol 50 re-mail-ck Remote Mail Checking Protocol Remote mail check protocol [unfinished] 51 la-maint IMP Logical Address Maintenance IMP (interface information processor) logical address Maintenance 52 xns-time XNS Time Protocol Xerox Network Service System Time Protocol 53 domain Domain Name Server Domain Name Server 54 xns-ch XNS Clearinghouse Xerox Network Service System Ticket Exchange 55 isi-gl ISI Graphics Language ISI Graphics Language 56 xns-auth XNS Authentication Xerox Network service system verification 57 ? any private terminal access Reserved personal terminal access 58 xns-mail XNS Mail Xerox network service system mail 59 any private file service Reserved personal file service 60 Unassigned Undefined 61 ni-mail NI MAIL NI mail? 62 acas ACA Services Asynchronous Communication Adapter Service 63 whois+ whois+ WHOIS+ 64 covia Communications Integrator (CI) Communication Interface 65 tacacs-ds TACACS-Database Service TACACS Database Service 66 sql*net Oracle SQL*NET Oracle SQL*NET 67 bootps Bootstrap Protocol Server Bootstrap Protocol Server 68 bootpc Bootstrap Protocol Client Bootstrap Protocol Client 69 tftp Trivial File Transfer Small File Transfer Protocol 70 gopher Gopher Information Retrieval Protocol 71 netrjs-1 Remote Job Service Remote Job Service 72 netrjs-2 Remote Job Service Remote Job Service 73 netrjs-3 Remote Job Service Remote Job Service 74 netrjs -4 Remote Job Service Remote Service Service 75 any private dial out service reserved for personal dial-out service 76 deos Distributed External Object Store Distributed external object storage 77 any private RJE service Reserved for personal remote job input service 78 vettcp vettcp Correct TCP ? 79 finger Finger Query information such as remote host online users 80 http World Wide Web HTTP Global Information Network Hypertext Transfer Protocol 81 hosts2-ns HOSTS2 Name Server HOST2 Name Service 82 xfer XFER Utility Transfer Utility 83 mit-ml-dev MIT ML Device Modular Smart Terminal ML device 84 ctf Common Trace Facility public tracking device 85 mit-ml-dev MIT ML Device modular intelligent terminal ML device 86 mfcobol Micro Focus Cobol Micro Focus Cobol programming language 87 any private terminal link reserved for personal terminal connection 88 kerberos Kerberos Kerberros Safety certification system
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