Servers Overview

Name

SERVERS -- Servers Available in XRPi.

Description

In the XRPi context, servers are processes which accept connections or data from users (i.e. clients) and provide specific services (e.g. file transfer) to those clients.

They are often associated with a specific TCP or UDP "service port" number, for example TCP port 21 for file transfer, UDP port 53 for DNS server and so on.

XRPi contains a number of servers and makes them available by default, although they may be disabled by the sysop if necessary.

The policy of making services available by default is an attempt to provide useful services to the Amateur Radio Packet Network (amprnet) with minimal effort on the part of the sysop. If services were disabled by default, most sysops wouldn't enable them, either because they didn't understand them, or because they couldn't be bothered.

Access to the benign servers is unrestricted, but most are protected by password and IP access control lists.

The following servers are available in XRPi

	Name     Port   Proto	Function
	---------------------------------------------------
	ECHO     7      TCP     Echoes data back
	DISCARD  9      TCP     Discards data
	FTP      21     TCP     File Transfer
	TELNET   23     TCP     XRPi user session
	DNS      53     UDP     Domain Name System
	FINGER   79     TCP     User information
	HTTP     80     TCP     Web server
	TTYLINK  87     TCP     XRPi user session
	RLOGIN   513    TCP     Remote Login (sysop)
	SOCKS    1080   TCP     SOCKS Proxy
	APRS     1448   TCP     Serves APRS data
	TELPROXY 2323   TCP     Raw TCP to AX25 bridge
	CHAT     3600   TCP     Conferencing
	AGWHOST  8000   TCP     AGW Packet Engine emulator
	RHP      9000   TCP     Remote application support
	PMS	    -     -     Personal Mail Server

For details of how to move the above ports or disable the servers, please see the TCP-PORTS page.

Brief Overview Of XRPi Servers

AGWHOST: Emulates the AGW TCP host interface, enabling XRPi to support applications (e.g. UI-View) that were designed for use with the AGW Packet Engine. (more info)
APRS: Shares APRS data between clients such as UI-View, RF ports and the Internet APRS-IS systems. (more info)
CHAT: Allows groups of users to hold conferences, either locally or globally via a network of interconnected servers. (more info)
DISCARD: This simply dumps anything sent to it. It is a useful tool for test purposes. This server is also available from the command prompt. (more info)
DNS: Answers Domain Name System (DNS) queries, to provide a hostname to IP-address translation service. (more info)
ECHO: Anything the user sends is echoed back to him. This is a useful tool for test purposes. This server is also available from the command prompt. (more info)
FINGER: Allows users to retrieve information about other users or any other topics provided by the sysop. This server is also available from the command prompt. (more info)
FTP: Allows sysops to upload, download, move and rename files, create and remove directories etc. Not available to users. (more info)
HTTP: Serves HTML (web) pages, and provides a rudimentary browser interface to XRPi. (more info)
PMS: A no-frills mailbox which can handle both private mail and bulletins. It is available from AX25 and the XRPi command prompt, but currently has no TCP port of its own. (more info)
RHP: Allows XRPi to support a wide range of applications which may be located on the same PC or remotely. (more info)
RLOGIN: Secure remote login for sysops only, providing full syop-mode access. (more info)
SOCKS Proxy: Circuit level proxy allowing applications to access external services through a firewall as an alternative to NAT. (more info)
TELNET: Provides regular user access to the XRPi command prompt.
TELPROXY: The Telnet Proxy server allows TCP/IP applications to make fully transparent raw binary connections (i.e. ones capable of handling compressed forwarding) to AX25 or NetRom destinations. (more info)
TTYLINK: Provides regular user access to the XRPi command prompt, i.e. duplicates the function of port 23.

See also

AGWHOST(6) -- AGWHOST Server
APRS(6) -- APRS Server
CHAT(6) -- Chat Server
DISCARD(6) -- Discard Server
DNS(6) -- DNS Server
ECHO(6) -- Echo Server
FINGER(6) -- Finger Server
FTP(6) -- FTP Server
HTTP(6) -- HTTP Server
PMS(6) -- Personal Mail Server
RHP(6) -- RHP Server
RLOGIN(6) -- Rlogin Server
SOCKS(6) -- SOCKS Proxy Server
TELPROXY(6) -- Telnet Proxy Server
TCP-PORTS(6) -- TCP Service Ports