creates a TCP/IP socket, binds it to the address
and listens on the socket for incoming connections.
On each incoming connection,
conditionally runs a program, with standard input reading from the socket,
and standard output writing to the socket, to handle this connection.
keeps listening on the socket for new connections, and can handle multiple
optionally checks for special instructions depending on the IP address or
hostname of the client that initiated the connection, see
either is a hostname, or a dotted-decimal IP address, or 0.
accepts connections to any local IP address.
accepts connections to
may be a name from /etc/services or a number.
consists of one or more arguments.
For each connection,
with file descriptor 0 reading from the network, and file descriptor 1
writing to the network.
By default it also sets up TCP-related environment variables, see
read instructions for handling new connections from the instructions
read instructions for handling new connections from the constant database
The constant database normally is created from an instructions directory by
This option only takes effect if the -i option is given.
While checking the instructions directory, check the time of last access of
the file that matches the clients address or hostname if any, discard and
remove the file if it wasn't accessed within the last
does not discard or remove a file if the user's write permission is not set,
for those files the timeout is disabled.
Default is 0, which means that the timeout is disabled.
Do not look up the local hostname in DNS, but use
This option must be set if
listens on port 53 to avoid loops.
Set uid and gid to the
uid and gid, as found in
is followed by a colon and a
set the gid to
gid, as found in
consists of a colon-separated list of group names,
set the group ids of all listed groups.
is prefixed with a colon, the
arguments are interpreted as uid and gids respectively, and not looked up in
the password or group file.
All supplementary groups are removed.
Handle up to
Default is 30.
If there are
defers acceptance of a new connection until an active connection is closed.
per host concurrency.
Allow only up to
connections from the same IP address simultaneously.
If there are
active connections from one IP address, new incoming connections from this IP
address are closed immediately.
is followed by
is written to the client if possible, before closing the connection.
for supported escape sequences in
For each accepted connection, the current per host concurrency is available
through the environment variable
can be overwritten by
doesn't keep track of connections.
Look up the client's hostname in DNS.
After looking up the client's hostname in DNS, look up the IP addresses in
DNS for that hostname, and forget about the hostname if none of the addresses
match the client's IP address.
You should set this option if you use hostname based instructions.
The -p option implies the -h option.
Allow a backlog of approximately
On some systems
is silently limited.
Default is 20.
no special environment.
Do not set up TCP-related environment variables.
Print verbose messsages to standard output.
Print more verbose messages to standard output.