Portmap
Encyclopedia
The port mapper is an ONC RPC
service that runs on network nodes that provide other ONC RPC services..
Version 2 of the port mapper protocol maps ONC RPC program number/version number pairs to the network port number for that version of that program. When an ONC RPC server is started, it will tell the port mapper, for each particular program number/version number pair it supports for a particular transport protocol (TCP
or UDP
), what port number it is using for that particular program number/version number pair on that transport protocol. Clients wishing to make an ONC RPC call to a particular version of a particular ONC RPC service must first contact the port mapper on the server machine to determine the actual TCP or UDP port to use.
Versions 3 and 4 of the protocol, called the rpcbind protocol, map a program number/version number pair, and an indicator that specifies a transport protocol, to a transport-layer endpoint address for that program number/version number pair on that transport protocol.
The port mapper service always uses TCP or UDP port 111; a fixed port is required for it, as a client would not be able to get the port number for the port mapper service from the port mapper itself.
The port mapper must be started before any other RPC servers are started.
The port mapper service first appeared in SunOS
2.0.
port 2049 or UDP
port 2049, depending on what transport protocol the client wants to use, and that the mount protocol, both version 1 and 2, is running, and can be reached at UDP port 644 or TCP port 645, depending on what transport protocol the client wants to use.
$ rpcinfo -p
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100024 1 udp 32770 status
100021 1 udp 32770 nlockmgr
100021 3 udp 32770 nlockmgr
100021 4 udp 32770 nlockmgr
100024 1 tcp 32769 status
100021 1 tcp 32769 nlockmgr
100021 3 tcp 32769 nlockmgr
100021 4 tcp 32769 nlockmgr
100005 1 udp 644 mountd
100005 1 tcp 645 mountd
100005 2 udp 644 mountd
100005 2 tcp 645 mountd
100005 3 udp 644 mountd
100005 3 tcp 645 mountd
Open Network Computing Remote Procedure Call
Open Network Computing Remote Procedure Call is a widely deployed remote procedure call system. ONC was originally developed by Sun Microsystems as part of their Network File System project, and is sometimes referred to as Sun ONC or Sun RPC...
service that runs on network nodes that provide other ONC RPC services..
Version 2 of the port mapper protocol maps ONC RPC program number/version number pairs to the network port number for that version of that program. When an ONC RPC server is started, it will tell the port mapper, for each particular program number/version number pair it supports for a particular transport protocol (TCP
Transmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
or UDP
User Datagram Protocol
The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
), what port number it is using for that particular program number/version number pair on that transport protocol. Clients wishing to make an ONC RPC call to a particular version of a particular ONC RPC service must first contact the port mapper on the server machine to determine the actual TCP or UDP port to use.
Versions 3 and 4 of the protocol, called the rpcbind protocol, map a program number/version number pair, and an indicator that specifies a transport protocol, to a transport-layer endpoint address for that program number/version number pair on that transport protocol.
The port mapper service always uses TCP or UDP port 111; a fixed port is required for it, as a client would not be able to get the port number for the port mapper service from the port mapper itself.
The port mapper must be started before any other RPC servers are started.
The port mapper service first appeared in SunOS
SunOS
SunOS is a version of the Unix operating system developed by Sun Microsystems for their workstation and server computer systems. The SunOS name is usually only used to refer to versions 1.0 to 4.1.4 of SunOS...
2.0.
Example portmap instance
This shows the different programs and their versions, and which ports they use. For example, it shows that NFS is running, both version 2 and 3, and can be reached at TCPTransmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
port 2049 or UDP
User Datagram Protocol
The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
port 2049, depending on what transport protocol the client wants to use, and that the mount protocol, both version 1 and 2, is running, and can be reached at UDP port 644 or TCP port 645, depending on what transport protocol the client wants to use.
$ rpcinfo -p
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100024 1 udp 32770 status
100021 1 udp 32770 nlockmgr
100021 3 udp 32770 nlockmgr
100021 4 udp 32770 nlockmgr
100024 1 tcp 32769 status
100021 1 tcp 32769 nlockmgr
100021 3 tcp 32769 nlockmgr
100021 4 tcp 32769 nlockmgr
100005 1 udp 644 mountd
100005 1 tcp 645 mountd
100005 2 udp 644 mountd
100005 2 tcp 645 mountd
100005 3 udp 644 mountd
100005 3 tcp 645 mountd
External links
- rpcbind– universal addresses to RPC program number mapper
- RFC 1833 - the specification of the ONC RPC port mapping protocol.