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Ejabbered

Architecture Overview

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  • Message buffer
  • No internal state kept. Helps in case of node failure.
  • Connection
    • The client-to-server connection (typically on TCP/5222) is handled by the module ejabberd_c2s. The server-to-server connection (typically on TCP/5269) is handled by the modules ejabberd_s2s, ejabberd_s2s_in, ejabber_s2s_out. The HTTP bindings are handled by the ejabberd_http module.
  • Router
    • The router handles the routing of most of the messages, i.e., when a Jabber client sends a to another entity, how is the message routed to the correct destination?
    • First ejabberd determines whether the message is a local or a remote one. It does so by looking at the "to" attribute to see if the host implied by the "to" attribute is hosted in itself.
    • If so, the message is local; and is handled by ejabberd_local; otherwise, it is treated as an s2s message.
  • Modules
    • In addition to the core Jabber and Router logics, there is a large part of the ejabberd that can be plugged in only when necessary, and they are called modules.
    • Modules can be started/stopped dynamically at any time, thus making the ejabberd server highly extensible even at runtime.
    • Modules are widely used for various extensions (the so-called 'XEP's).
  • Hooks
    • A hook is a way by which you can change the behavior of ejabberd by injecting your new code into the system, without changing any existing code.
    • For example, if you want to roll up your message filter to filter out messages you don't want, you can add a module hooking to the "filter_packet/3" hook.
    • If you want to keep track of all the messages clients sent, you can write a function hooking to 'user_send_packet/3'.
  • Access Control
    • Access Control. All users (including real jabber client users as well as administrators) are stored the same way in ejabberd.
    • Their privileges are determined by the groups they belong to.
    • Hence, the access control modules in ejabberd allow us to distinguish users from their groups, thus providing different services for different users.
    • Utils and Libraries. Some other libraries and utils exist in ejabberd for common purposes, e.g.: XML processing, SASL authentication, Encodings, Logger, etc. It is worth noting the ejabberd_logger is a very good logger module perfectly usable by any other projects.
  • The main difference between the jabber:component:* namespaces and the 'jabber: client' or 'jabber: server' namespace is authentication.

PUB-SUB

  • Subscribe

  • Unsubscribe

  • Configure

  • Retrieve message/item

  • Publish message

  • Delete message

  • Create node

  • Configure

  • Delete Node

  • Purge Node

  • Manage subscription

  • Manage affiliation

  • A core router for high-level use case implementation

  • Plugins to handle nodes, subscriptions, items at a lower level and interfacing with the database

  • NodeTree Plugin

    • Handles storage and organization of PubSub nodes
    • get create delete node
    • tree both internal odbc backend
    • virtual no backend
    • dag XEP 0248

  • node_flat

  • odbc - open database connectivity

  • https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

IRC

  • Server
    • backbone
  • Clients
    • Unique nickname having a max length of 9 Chars
  • Channels

    • for channel

    • @ for operator

The standard structure of a network of IRC servers is a tree.[35] Messages are routed along only necessary branches of the tree but network state is sent to every server[36] and there is generally a high degree of implicit trust between servers. This architecture has a number of problems. A misbehaving or malicious server can cause major damage to the network[37] and any changes in structure, whether intentional or a result of conditions on the underlying network, require a net-split and net-join. This results in a lot of network traffic spurious quit/join messages to users[38] and temporary loss of communication to users on the splitting servers. Adding a server to a large network means a large background bandwidth load on the network and a large memory load on the server. Once established, however, each message to multiple recipients is delivered in a fashion similar to multicast, meaning each message travels a network link exactly once.[39] This is a strength in comparison to non-multicasting protocols such as Simple Mail Transfer Protocol (SMTP) or Extensible Messaging and Presence Protocol (XMPP).

  • Servers provide the three basic services required for real-time conferencing defined by the "Internet Relay Chat: Architecture" [IRC-ARCH]: client locator (via the client protocol [IRC-CLIENT]), message relaying (via the server protocol defined in this document) and channel hosting and management (following specific rules [IRC- CHAN]).

Actor Model

  • Actors instead of objects
  • No shared state between actors
  • Asynchronous message passing
  • Mailboxes to buffer incoming messages
  • React to messages
    • change own state
    • can send messages to others
  • Messages
  • Mailbox - (Message Queue)

System Up & Running takeaways

Log

  • /usr/local/var/log/ejabberd/ejabberd.log

Scripts

/usr/local/sbin/ejabberdctl
/usr/local/sbin/ejabberdctl start 
/usr/local/sbin/ejabberdctl stop
/usr/local/sbin/ejabberdctl live
/etc/init.d/ejabberd
sudo vim /etc/ejabberd/ejabberd.yml
sudo cat /usr/local/etc/ejabberd/ejabberd.yml
ejabberdctl register admin1 example.org FgT5bk3

Running endpoint

Port scan result

PORT STATE SERVICE

21/tcp open ftp

22/tcp open ssh

25/tcp filtered smtp

26/tcp open rsftp

53/tcp open domain

80/tcp open HTTP

110/tcp open pop3

111/tcp filtered rpcbind

135/tcp filtered msrpc

139/tcp filtered netbios-ssn

143/tcp open imap

443/tcp open https

445/tcp filtered microsoft-ds

465/tcp open smtps

587/tcp open submission

993/tcp open imaps

995/tcp open pop3s

2222/tcp open EtherNetIP-1

3306/tcp open MySQL

5432/tcp open PostgreSQL

6666/tcp filtered irc

6667/tcp filtered irc

12345/tcp filtered netbus

  • Other alternative
    • Matrix, which is pull-based

References