NAME¶
tcpsvd - TCP/IP service daemon
SYNOPSIS¶
tcpsvd [-hpEvv] [-c
n] [-C n:msg] [-b n] [-u
user] [-l name] [-i dir|-x
cdb] [ -t
sec]
host port prog
DESCRIPTION¶
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 instructions depending on the IP
address or hostname of the client that initiated the connection, see
ipsvd-instruct(5).
OPTIONS¶
- 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. Set uid and gid to the user's uid
and gid, as found in /etc/passwd, before running prog. If
user is followed by a colon and a group, set the gid to
group's gid, as found in /etc/group, instead of
user's gid. If group consists of a colon-separated list of
group names, set the group ids of all listed groups. If user is
prefixed with a colon, the user and all group arguments are
interpreted as uid and gids respectively, and not looked up in the
password or group file. 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.
SEE ALSO¶
ipsvd(7),
sslsvd(8),
udpsvd(8),
ipsvd-instruct(5),
ipsvd-cdb(8),
sslio(8)
http://smarden.org/ipsvd/
AUTHOR¶
Gerrit Pape <pape@smarden.org>