G. Pape
ipsvd
tcpsvd - TCP/IP service daemon
tcpsvd [-hpEvv] [-c n] [-C n:msg]
[-b n] [-u user] [-l name] [-i dir|-x cdb] [ -t sec] host port prog
tcpsvd
creates a TCP/IP socket, binds it to the address host:port, and listens
on the socket for incoming connections.
On each incoming connection, tcpsvd
conditionally runs a program, with standard input reading from the socket,
and standard output writing to the socket, to handle this connection. tcpsvd
keeps listening on the socket for new connections, and can handle multiple
connections simultaneously.
tcpsvd optionally checks for special intructions
depending on the IP address or hostname of the client that initiated the
connection, see ipsvd-instruct(5).
- host
- host either is a hostname,
or a dotted-decimal IP address, or 0. If host is 0, tcpsvd accepts connections
to any local IP address.
- port
- tcpsvd accepts connections to host:port. port
may be a name from /etc/services or a number.
- prog
- prog consists of one
or more arguments. For each connection, tcpsvd normally runs prog, 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 tcp-environ(5)
- -i dir
- read instructions for handling new connections
from the instructions directory dir. See ipsvd-instruct(5) for details.
- -x
cdb
- read instructions for handling new connections from the constant database
cdb. The constant database normally is created from an instructions directory
by running ipsvd-cdb(8).
- -t sec
- timeout. 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
sec seconds; tcpsvd 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.
- -l name
- local hostname. Do
not look up the local hostname in DNS, but use name as hostname. This option
must be set if tcpsvd listens on port 53 to avoid loops.
- -u user[:group]
- drop permissions. Switch user ID to user’s UID, and group ID to user’s primary
GID after creating and binding to the socket. If user is followed by a colon
and a group name, the group ID is switched to the GID of group instead.
All supplementary groups are removed.
- -c n
- concurrency. Handle up to n connections
simultaneously. Default is 30. If there are n connections active, tcpsvd
defers acceptance of a new connection until an active connection is closed.
- -C n[:msg]
- per host concurrency. Allow only up to n connections from the
same IP address simultaneously. If there are n active connections from one
IP address, new incoming connections from this IP address are closed immediately.
If n is followed by :msg, the message msg is written to the client if possible,
before closing the connection. By default msg is empty. See ipsvd-instruct(5)
for supported escape sequences in msg.
For each accepted connection, the
current per host concurrency is available through the environment variable
TCPCONCURRENCY. n and msg can be overwritten by ipsvd(7) instructions, see
ipsvd-instruct(5). By default tcpsvd doesn’t keep track of connections.
- -h
- Look
up the client’s hostname in DNS.
- -p
- paranoid. 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.
- -b n
- backlog. Allow a backlog of approximately
n TCP SYNs. On some systems n is silently limited. Default is 20.
- -E
- no special
environment. Do not set up TCP-related environment variables.
- -v
- verbose. Print
verbose messsages to standard output.
- -vv
- more verbose. Print more verbose
messages to standard output.
ipsvd(7), udpsvd(8), ipsvd-instruct(5),
ipsvd-cdb(8), sslio(8)
http://smarden.org/ipsvd/
Gerrit Pape <pape@smarden.org>
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