{"id":19600354,"url":"https://github.com/0xkayala/common-protocols","last_synced_at":"2026-03-04T11:03:09.323Z","repository":{"id":189201289,"uuid":"680240405","full_name":"0xKayala/Common-Protocols","owner":"0xKayala","description":"A Dictionary of Common-Protocols such as TCP, UDP, ICMP and VoIP","archived":false,"fork":false,"pushed_at":"2023-08-18T17:40:03.000Z","size":38,"stargazers_count":2,"open_issues_count":0,"forks_count":1,"subscribers_count":2,"default_branch":"main","last_synced_at":"2025-02-26T15:31:43.537Z","etag":null,"topics":["icmp","protocols","tcp","udp","voip"],"latest_commit_sha":null,"homepage":"https://github.com/0xKayala/Common-Protocols","language":null,"has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"gpl-3.0","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/0xKayala.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null}},"created_at":"2023-08-18T17:30:49.000Z","updated_at":"2024-10-03T05:17:36.000Z","dependencies_parsed_at":null,"dependency_job_id":"4b79f4b1-ca1d-45be-bb7e-da30f668428f","html_url":"https://github.com/0xKayala/Common-Protocols","commit_stats":null,"previous_names":["0xkayala/common-protocols"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/0xKayala/Common-Protocols","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/0xKayala%2FCommon-Protocols","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/0xKayala%2FCommon-Protocols/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/0xKayala%2FCommon-Protocols/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/0xKayala%2FCommon-Protocols/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/0xKayala","download_url":"https://codeload.github.com/0xKayala/Common-Protocols/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/0xKayala%2FCommon-Protocols/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":30078416,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-03-04T08:01:56.766Z","status":"ssl_error","status_checked_at":"2026-03-04T08:00:42.919Z","response_time":59,"last_error":"SSL_connect returned=1 errno=0 peeraddr=140.82.121.5:443 state=error: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["icmp","protocols","tcp","udp","voip"],"created_at":"2024-11-11T09:14:31.278Z","updated_at":"2026-03-04T11:03:09.255Z","avatar_url":"https://github.com/0xKayala.png","language":null,"readme":"# Common Protocols\n\n\u003cp\u003eInternet protocols are standardized rules and guidelines defined in RFCs that specify how devices on a network should communicate with each other. They ensure that devices on a network can exchange information consistently and reliably, regardless of the hardware and software used. For devices to communicate on a network, they need to be connected through a communication channel, such as a wired or wireless connection. The devices then exchange information using a set of standardized protocols that define the format and structure of the data being transmitted. The two main types of connections used on networks are \u003ca href=\"https://en.wikipedia.org/wiki/Transmission_Control_Protocol\"\u003eTransmission Control Protocol\u003c/a\u003e (\u003ccode\u003eTCP\u003c/code\u003e) and \u003ca href=\"https://en.wikipedia.org/wiki/User_Datagram_Protocol\"\u003eUser Datagram Protocol\u003c/a\u003e (\u003ccode\u003eUDP\u003c/code\u003e).\u003c/p\u003e\n\u003cp\u003eWe need to deal with and know the different and most used protocols. As we have already learned, these protocols are the basis of all communication between our devices and computers in the networks. We have compiled below many of these protocols that we will be dealing with throughout the modules. The better we understand them, the more effectively we can work with them.\u003c/p\u003e\n\n## Transmission Control Protocol\n\u003cp\u003e\u003ccode\u003eTCP\u003c/code\u003e is a \u003ccode\u003econnection-oriented\u003c/code\u003e protocol that establishes a virtual connection between two devices before transmitting data by using a \u003ca href=\"https://en.wikipedia.org/wiki/Transmission_Control_Protocol#Connection_establishment\"\u003eThree-Way-Handshake\u003c/a\u003e. This connection is maintained until the data transfer is complete, and the devices can continue to send data back and forth as long as the connection is active.\u003c/p\u003e\n\u003cp\u003eFor example, When we enter a URL into our web browser, the browser sends an HTTP request to the server hosting the website using \u003ccode\u003eTCP\u003c/code\u003e. The server responds by sending the HTML code for the website back to the browser using \u003ccode\u003eTCP\u003c/code\u003e. The browser then uses this code to render the website on our screen. This process relies on a \u003ccode\u003eTCP\u003c/code\u003e connection being established between the browser and the web server and maintained until the data transfer is complete. As a result, \u003ccode\u003eTCP\u003c/code\u003e is reliable but slower than UDP because it requires additional overhead for establishing and maintaining the connection.\u003c/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eProtocol\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eAcronym\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003ePort\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelnet\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eTelnet\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e23\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eRemote login service\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecure Shell\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSSH\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e22\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eSecure remote login service\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSimple Network Management Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSNMP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e161-162\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eManage network devices\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHyper Text Transfer Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eHTTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e80\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to transfer webpages\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHyper Text Transfer Protocol Secure\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eHTTPS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e443\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to transfer secure webpages\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDomain Name System\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eDNS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e53\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eLookup domain names\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFile Transfer Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eFTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e20-21\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to transfer files\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTrivial File Transfer Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eTFTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e69\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to transfer files\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetwork Time Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eNTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e123\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eSynchronize computer clocks\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSimple Mail Transfer Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSMTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e25\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for email transfer\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePost Office Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003ePOP3\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e110\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to retrieve emails\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Message Access Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIMAP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e143\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to access emails\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eServer Message Block\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSMB\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e445\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to transfer files\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetwork File System\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eNFS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e111\u003c/code\u003e, \u003ccode\u003e2049\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to mount remote systems\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBootstrap Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eBOOTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e67\u003c/code\u003e, \u003ccode\u003e68\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to bootstrap computers\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eKerberos\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eKerberos\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e88\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for authentication and authorization\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLightweight Directory Access Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eLDAP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e389\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for directory services\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRemote Authentication Dial-In User Service\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eRADIUS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1812\u003c/code\u003e, \u003ccode\u003e1813\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for authentication and authorization\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDynamic Host Configuration Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eDHCP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e67\u003c/code\u003e, \u003ccode\u003e68\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to configure IP addresses\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRemote Desktop Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eRDP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e3389\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for remote desktop access\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetwork News Transfer Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eNNTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e119\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to access newsgroups\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRemote Procedure Call\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eRPC\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e135\u003c/code\u003e, \u003ccode\u003e137-139\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to call remote procedures\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIdentification Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIdent\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e113\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to identify user processes\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Control Message Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eICMP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e0-255\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed to troubleshoot network issues\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Group Management Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIGMP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e0-255\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for multicasting\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOracle DB (Default/Alternative) Listener\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eoracle-tns\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1521\u003c/code\u003e/\u003ccode\u003e1526\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThe Oracle database default/alternative listener is a service that runs on the database host and receives requests from Oracle clients.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIngres Lock\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eingreslock\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1524\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIngres database is commonly used for large commercial applications and as a backdoor that can execute commands remotely via RPC.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSquid Web Proxy\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003ehttp-proxy\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e3128\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eSquid web proxy is a caching and forwarding HTTP web proxy used to speed up a web server by caching repeated requests.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecure Copy Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSCP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e22\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eSecurely copy files between systems\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSession Initiation Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSIP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e5060\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for VoIP sessions\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSimple Object Access Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSOAP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e80\u003c/code\u003e, \u003ccode\u003e443\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for web services\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecure Socket Layer\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSSL\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e443\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eSecurely transfer files\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTCP Wrappers\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eTCPW\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e113\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for access control\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetwork Time Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eNTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e123\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eSynchronize computer clocks\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Security Association and Key Management Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eISAKMP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e500\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for VPN connections\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMicrosoft SQL Server\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003ems-sql-s\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1433\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for client connections to the Microsoft SQL Server.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eKerberized Internet Negotiation of Keys\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eKINK\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e892\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for authentication and authorization\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOpen Shortest Path First\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eOSPF\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e520\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for routing\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePoint-to-Point Tunneling Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003ePPTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1723\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIs used to create VPNs\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRemote Execution\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eREXEC\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e512\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis protocol is used to execute commands on remote computers and send the output of commands back to the local computer.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRemote Login\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eRLOGIN\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e513\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis protocol starts an interactive shell session on a remote computer.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eX Window System\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eX11\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e6000\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a computer software system and network protocol that provides a graphical user interface (GUI) for networked computers.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelational Database Management System\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eDB2\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e50000\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eRDBMS is designed to store, retrieve and manage data in a structured format for enterprise applications such as financial systems, customer relationship management (CRM) systems.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\n## User Datagram Protocol\n\u003cp\u003eOn the other hand, \u003ccode\u003eUDP\u003c/code\u003e is a \u003ccode\u003econnectionless\u003c/code\u003e protocol, which means it does not establish a virtual connection before transmitting data. Instead, it sends the data packets to the destination without checking to see if they were received.\u003c/p\u003e\n\u003cp\u003eFor example, when we stream or watch a video on a platform like YouTube, the video data is transmitted to our device using \u003ccode\u003eUDP\u003c/code\u003e. This is because the video can tolerate some data loss, and the transmission speed is more important than the reliability. If a few packets of video data are lost along the way, it will not significantly impact the overall quality of the video. This makes \u003ccode\u003eUDP\u003c/code\u003e faster than TCP but less reliable because there is no guarantee that the packets will reach their destination.\u003c/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eProtocol\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eAcronym\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003ePort\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eDomain Name System\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eDNS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e53\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a protocol to resolve domain names to IP addresses.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTrivial File Transfer Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eTFTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e69\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is used to transfer files between systems.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetwork Time Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eNTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e123\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt synchronizes computer clocks in a network.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSimple Network Management Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSNMP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e161\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt monitors and manages network devices remotely.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRouting Information Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eRIP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e520\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is used to exchange routing information between routers.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Key Exchange\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIKE\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e500\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eInternet Key Exchange\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBootstrap Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eBOOTP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e68\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is used to bootstrap hosts in a network.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDynamic Host Configuration Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eDHCP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e67\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is used to assign IP addresses to devices in a network dynamically.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelnet\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eTELNET\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e23\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a text-based remote access communication protocol.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMySQL\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eMySQL\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e3306\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is an open-source database management system.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTerminal Server\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eTS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e3389\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a remote access protocol used for Microsoft Windows Terminal Services by default.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetBIOS Name\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003enetbios-ns\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e137\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is used in Windows operating systems to resolve NetBIOS names to IP addresses on a LAN.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMicrosoft SQL Server\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003ems-sql-m\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1434\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eUsed for the Microsoft SQL Server Browser service.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUniversal Plug and Play\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eUPnP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e1900\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a protocol for devices to discover each other on the network and communicate.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePostgreSQL\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003ePGSQL\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e5432\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is an object-relational database management system.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVirtual Network Computing\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eVNC\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e5900\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a graphical desktop sharing system.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eX Window System\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eX11\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e6000-6063\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a computer software system and network protocol that provides GUI on Unix-like systems.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSyslog\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eSYSLOG\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e514\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a standard protocol to collect and store log messages on a computer system.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Relay Chat\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIRC\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e194\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a real-time Internet text messaging (chat) or synchronous communication protocol.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOpenPGP\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eOpenPGP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e11371\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a protocol for encrypting and signing data and communications.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Protocol Security\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIPsec\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e500\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIPsec is also a protocol that provides secure, encrypted communication. It is commonly used in VPNs to create a secure tunnel between two devices.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternet Key Exchange\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eIKE\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e11371\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eIt is a protocol for encrypting and signing data and communications.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eX Display Manager Control Protocol\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003eXDMCP\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003e\u003ccode\u003e177\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eXDMCP is a network protocol that allows a user to remotely log in to a computer running the X11.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\n## ICMP\n\u003cp\u003e\u003ca href=\"https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol\"\u003eInternet Control Message Protocol\u003c/a\u003e (\u003ccode\u003eICMP\u003c/code\u003e) is a protocol used by devices to communicate with each other on the Internet for various purposes, including error reporting and status information. It sends requests and messages between devices, which can be used to report errors or provide status information.\u003c/p\u003e\n\u003ch4\u003eICMP Requests\u003c/h4\u003e\n\u003cp\u003eA request is a message sent by one device to another to request information or perform a specific action. An example of a request in ICMP is the \u003ccode\u003eping\u003c/code\u003e request, which tests the connectivity between two devices. When one device sends a ping request to another, the second device responds with a \u003ccode\u003eping reply\u003c/code\u003e message.\u003c/p\u003e\n\u003ch4\u003eICMP Messages\u003c/h4\u003e\n\u003cp\u003eA message in ICMP can be either a request or a reply. In addition to ping requests and responses, ICMP supports other types of messages, such as error messages, \u003ccode\u003edestination unreachable\u003c/code\u003e, and \u003ccode\u003etime exceeded\u003c/code\u003e messages. These messages are used to communicate various types of information and errors between devices on the network.\u003c/p\u003e\n\u003cp\u003eFor example, if a device tries to send a packet to another device and the packet cannot be delivered, the device can use ICMP to send an error message back to the sender. ICMP has two different versions:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ccode\u003eICMPv4\u003c/code\u003e: For IPv4 only\u003c/li\u003e\n\u003cli\u003e\n\u003ccode\u003eICMPv6\u003c/code\u003e: For IPv6 only\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eICMPv4 is the original version of \u003ccode\u003eICMP\u003c/code\u003e, developed for use with IPv4. It is still widely used and is the most common version of ICMP. On the other hand, ICMPv6 was developed for IPv6. It includes additional functionality and is designed to address some of the limitations of ICMPv4.\u003c/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eRequest Type\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eEcho Request\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message tests whether a device is reachable on the network. When a device sends an echo request, it expects to receive an echo reply message. For example, the tools \u003ccode\u003etracert\u003c/code\u003e (Windows) or \u003ccode\u003etraceroute\u003c/code\u003e (Linux) always send ICMP echo requests.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eTimestamp Request\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message determines the time on a remote device.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eAddress Mask Request\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message is used to request the subnet mask of a device.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eMessage Type\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eEcho reply\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message is sent in response to an echo request message.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eDestination unreachable\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message is sent when a device cannot deliver a packet to its destination.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eRedirect\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eA router sends this message to inform a device that it should send its packets to a different router.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003e time exceeded\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message is sent when a packet has taken too long to reach its destination.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eParameter problem\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message is sent when there is a problem with a packet's header.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eSource quench\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eThis message is sent when a device receives packets too quickly and cannot keep up. It is used to slow down the flow of packets.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAnother crucial part of ICMP for us is the \u003ca href=\"https://en.wikipedia.org/wiki/Time_to_live\"\u003eTime-To-Live\u003c/a\u003e (\u003ccode\u003eTTL\u003c/code\u003e) field in the ICMP packet header that limits the packet's lifetime as it travels through the network. It prevents packets from circulating indefinitely on the network in the event of routing loops. Each time a packet passes through a router, the router decrements the \u003ccode\u003eTTL value by 1\u003c/code\u003e. When the TTL value reaches \u003ccode\u003e0\u003c/code\u003e, the router discards the packet and sends an ICMP \u003ccode\u003eTime Exceeded\u003c/code\u003e message back to the sender.\u003c/p\u003e\n\u003cp\u003eWe can also use \u003ccode\u003eTTL\u003c/code\u003e to determine the number of hops a packet has taken and the approximate distance to the destination. For example, if a packet has a \u003ccode\u003eTTL\u003c/code\u003e of 10 and takes 5 hops to reach its destination, it can be inferred that the destination is approximately 5 hops away. For example, if we see a ping with the \u003ccode\u003eTTL\u003c/code\u003e value of \u003ccode\u003e122\u003c/code\u003e, it could mean that we are dealing with a Windows system (\u003ccode\u003eTTL 128\u003c/code\u003e by default) that is 6 hops away.\u003c/p\u003e\n\u003cp\u003eHowever, it is also possible to guess the operating system based on the default \u003ccode\u003eTTL\u003c/code\u003e value used by the device. Each operating system typically has a default \u003ccode\u003eTTL\u003c/code\u003e value when sending packets. This value is set in the packet's header and is decremented by 1 each time the packet passes through a router. Therefore, examining a device's default \u003ccode\u003eTTL\u003c/code\u003e value makes it possible to infer which operating system the device is using. For example: Windows systems (\u003ccode\u003e2000/XP/2003/Vista/10\u003c/code\u003e) typically have a default \u003ccode\u003eTTL\u003c/code\u003e value of 128, while macOS and Linux systems typically have a default \u003ccode\u003eTTL\u003c/code\u003e value of 64 and Solaris' default \u003ccode\u003eTTL\u003c/code\u003e value of 255. However, it is important to note that the user can change these values, so they should be independent of a definitive way to determine a device's operating system.\u003c/p\u003e\n\n## VoIP\n\u003cp\u003e\u003ca href=\"https://www.fcc.gov/general/voice-over-internet-protocol-voip\"\u003eVoice over Internet Protocol\u003c/a\u003e (\u003ccode\u003eVoIP\u003c/code\u003e) is a method of transmitting voice and multimedia communications. For example, it allows us to make phone calls using a broadband internet connection instead of a traditional phone line, like Skype, Whatsapp, Google Hangouts, Slack, Zoom, and others.\u003c/p\u003e\n\u003cp\u003eThe most common VoIP ports are \u003ccode\u003eTCP/5060\u003c/code\u003e and \u003ccode\u003eTCP/5061\u003c/code\u003e, which are used for the \u003ca href=\"https://en.wikipedia.org/wiki/Session_Initiation_Protocol\"\u003eSession Initiation Protocol\u003c/a\u003e (SIP). However, the port \u003ccode\u003eTCP/1720\u003c/code\u003e may also be used by some VoIP systems for the \u003ca href=\"https://en.wikipedia.org/wiki/H.323\"\u003eH.323 protocol\u003c/a\u003e, a set of standards for multimedia communication over packet-based networks. Still, SIP is more widely used than H.323 in VoIP systems.\u003c/p\u003e\n\u003cp\u003eNevertheless, SIP is a signaling protocol for initiating, maintaining, modifying, and terminating real-time sessions involving video, voice, messaging, and other communications applications and services between two or more endpoints on the Internet. Therefore, it uses requests and methods between the endpoints. The most common SIP requests and methods are:\u003c/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eMethod\u003c/strong\u003e\u003c/th\u003e\n\u003cth\u003e\u003cstrong\u003eDescription\u003c/strong\u003e\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eINVITE\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eInitiates a session or invites another endpoint to participate.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eACK\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eConfirms the receipt of an INVITE request.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eBYE\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eTerminate a session.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eCANCEL\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eCancels a pending INVITE request.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eREGISTER\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eRegisters a SIP user agent (UA) with a SIP server.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ccode\u003eOPTIONS\u003c/code\u003e\u003c/td\u003e\n\u003ctd\u003eRequests information about the capabilities of a SIP server or user agent, such as the types of media it supports.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003ch4\u003eInformation Disclosure\u003c/h4\u003e\n\u003cp\u003eHowever, SIP allows us to enumerate existing users for potential attacks. This can be done for various purposes, such as determining a user's availability, finding out information about the user's capabilities or services, or performing brute-force attacks on user accounts later on.\u003c/p\u003e\n\u003cp\u003eOne of the possible ways to enumerate users is the SIP \u003ccode\u003eOPTIONS\u003c/code\u003e request. It is a method used to request information about the capabilities of a SIP server or user agents, such as the types of media it supports, the codecs it can decode, and other details. The \u003ccode\u003eOPTIONS\u003c/code\u003e request can probe a SIP server or user agent for information or test its connectivity and availability.\u003c/p\u003e\n\u003cp\u003eDuring our analysis, it is possible to discover a \u003ccode\u003eSEPxxxx.cnf\u003c/code\u003e file, where \u003ccode\u003exxxx\u003c/code\u003e is a unique identifier, is a configuration file used by Cisco Unified Communications Manager, formerly known as Cisco CallManager, to define the settings and parameters for a Cisco Unified IP Phone. The file specifies the phone model, firmware version, network settings, and other details.\u003c/p\u003e\n","funding_links":[],"categories":[],"sub_categories":[],"project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2F0xkayala%2Fcommon-protocols","html_url":"https://awesome.ecosyste.ms/projects/github.com%2F0xkayala%2Fcommon-protocols","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2F0xkayala%2Fcommon-protocols/lists"}