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inndstart(8)
NAME
inndstart - Start innd
SYNOPSIS
inndstart [-P port] [-I address] [innd-options]
DESCRIPTION
The purpose of inndstart is to raise system file descriptor limits, open
the privileged news transfer port, and then start innd(8), passing it the
open file descriptor for the news port. inndstart is used since only
privileged programs can perform those two operations and since innd should
not run privileged. It is installed setuid root and drops privileges to
the news user (set at configure time) before running innd.
Normally there is no need to run inndstart directly. Instead, run
rc.news(8) as the news user, and it will handle running inndstart
appropriately for you.
Since inndstart is setuid root, it is extremely restrictive about who can
run it and what it is willing to do. See the section on "SECURITY" for the
full details.
inndstart can only be run by the news user; if run by any other user, it
will abort. It will also only bind to ports 119, 433, or a port number
given at configure time with --with-innd-port among those ports below 1024,
although it can bind to any port above 1024. This is to prevent various
security exploits possible by binding to arbitrary privileged ports.
Before running innd, inndstart cleans out the environment and sets only
those environment variables listed in the section on "ENVIRONMENT".
OPTIONS
-P port
Bind to port instead of whatever is specified by port in inn.conf(5).
Note that this is subject to the constraints mentioned above.
-I address
Bind as address instead of whatever is specified by bindaddress in
inn.conf(5). The default behavior is to bind to INADDR_ANY, and that's
what's desired almost all the time. This option, and the inn.conf(5)
parameter, may be useful if the machine has multiple interface cards
and innd should only be listening on a particular one.
All other options given on the command line are passed verbatim to innd.
In addition, inndstart will give the -p option to innd, specifying the file
descriptor of the open network socket.
SECURITY
inndstart is setuid root, and therefore an expected point of attack. It
has therefore been carefully written with security in mind. In a normal
INN installation, it is installed setuid root and executable only by users
in the news group.
Ideally, everything about inndstart's operations would be hard-coded so
that it could not be modified. Fighting against this desire, however, is
the ideal that as much of INN's operation as possible should be
configurable at run-time using inn.conf(5), and the news system should be
able to an alternate inn.conf by setting INNCONF to the path to that file
before starting any programs. The configuration data therefore can't be
trusted.
The security model used is:
· inndstart can only be executed by the news user and news group, as
determined at configure time and compiled into inndstart as constants.
Similarly, inndstart will always setuid() and setgid() to those users
before running innd. This is to prevent a user other than news but in
the news group from using inndstart to leverage that access into access
to the news account.
· As mentioned above, inndstart will only bind to a very limited set of
ports below 1024. There are various attacks that can be performed using
random low-numbered ports, including exploits of the rsh family of
commands on some systems.
· inndstart does as little as possible as root, dropping privileges before
performing any operations that do not require elevated privileges.
This program therefore gives the news user the ability to revoke system
file descriptor limits and bind to the news port, and nothing else.
DIAGNOSTICS
inndstart may log the following messages to syslog (like the rest of INN,
syslog is the best place to find detailed debugging information):
can't bind: %s
(Fatal) Unable to bind to the designated port. This usually means that
something else is already running on the news port. Check with
netstat(8) and make sure that inetd(8) doesn't think it's running a
service on the same port you're trying to run innd on.
can't exec %s: %s
(Fatal) inndstart was unable to execute innd. Make sure that pathbin
is set correctly in inn.conf and that innd is located in that directory
and is executable by the news user.
can't getrlimit(NOFILE)
(Warning) Unable to obtain the current system resource limit on file
descriptors. Chances are something is wrong with the *rlimit()
functions. The file descriptor limit was left unchanged from the
system default.
can't open socket: %s
(Fatal) Something went wrong in creating the network socket. Chances
are your system is out of resources of some kind.
can't setgid(%d): %s
(Fatal) Dropping privileges to the news group failed for some reason.
can't setgroups: %s
(Warning) Dropping all supplemental groups except the news group failed
for some reason, and the process group membership was left unchanged.
This message may indicate a minor security hole if the news user is in
extra groups.
can't setrlimit(NOFILE, %d)
(Warning) Unable to set the system file descriptor limit to the
specified value. Either that value is too high for your system or
something else went wrong. The file descriptor limit was left
unchanged. Try changing rlimitnofile in inn.conf to a smaller value.
can't setsockopt: %s
(Warning) inndstart attempts to set SO_REUSEADDR so that if innd exits,
it can be restarted again immediately without waiting for the port to
time out. For some reason, this failed, and that option was not set on
the port.
can't setuid(%d): %s
(Fatal) Dropping privileges to the news user failed for some reason.
can't stat pathrun (%s): %s
(Fatal) pathrun as specified in inn.conf doesn't exist.
getgrnam(%s) failed
(Fatal) Unable to determine the GID for the compiled-in news group. Is
the news group listed in /etc/group?
getpwnam(%s) failed
(Fatal) Unable to determine the UID for the compiled-in news user. Is
the news user listed in /etc/passwd?
invalid address %s
(Fatal) -I was specified on the command line, but the argument wasn't a
valid address. Addresses must be given as numeric IP addresses.
invalid bindaddress in inn.conf (%s)
(Fatal) The bindaddress specified in inn.conf could not be converted to
an IP address. See inn.conf(5) for more information about valid
values.
invalid port %s
(Fatal) -P was specified on the command line, but the argument wasn't a
valid port. Ports must be port numbers; service names are not allowed.
missing address after -I
(Fatal) -I was given on the command line, but no address was given
after the option.
missing port after -P
(Fatal) -P was given on the command line, but no port was given after
the option.
pathrun (%s) not a directory
(Fatal) pathrun as specified in inn.conf isn't a directory. This is
where innd will create its local control socket; it should always be a
directory.
pathrun (%s) owned by group %d, not %s (%d)
(Fatal) pathrun specified in inn.conf must be owned by the news group.
This is checked for security reasons.
pathrun (%s) owned by user %d, not %s (%d)
(Fatal) pathrun specified in inn.conf must be owned by the news user.
This is checked for security reasons.
ran by GID %d, who isn't %s (%d)
(Fatal) Someone not in the news group attempted to run inndstart. If
you were running inndstart as the news user, make sure that the news
user's default group is the news group you picked at compile time
(`news' by default).
ran by UID %d, who isn't %s (%d)
(Fatal) Someone other than the news user attempted to run inndstart.
inndstart may only be run by the news user for security reasons.
seteuid(%d) failed: %s
(Fatal) Unable to change the effective UID. This usually means that
inndstart was installed with the wrong permissions. If it does have
the correct permissions (setuid root) and seteuid() to root (UID 0) is
failing, this may mean that your system has seteuid() but doesn't have
support for POSIX saved UIDs. If this is the case, please report this
to the INN maintainers.
setreuid(%d, %d) failed: %s
(Fatal) Unable to change the real and effective UIDs. This message
usually means that inndstart was installed with the wrong permissions.
tried to bind to port %d
(Fatal) inndstart was told to bind to a low numbered port (under 1024)
other than 119, 433, or a port number given at configure time. This is
not allowed for security reasons.
EXAMPLES
Normally, inndstart is never run directly. However, a simple way to just
restart innd without running any other auxilliary programs or performing
any of the other checks done by rc.news(8) is to just run:
inndstart
as the news user.
To start innd on port 433, passing it the `-c21' option, use:
inndstart -P433 -c21
ENVIRONMENT
One environment variable affects the operation of inndstart itself:
INNCONF The full path to the inn.conf(5) file to read, rather than the
default. This can be used to run multiple copies of INN on the
same machine with different settings.
When executing innd, inndstart cleans out the entire environmnent and sets
only the following variables:
BIND_INADDR
Passed verbatim from inndstart's environment. This is apparently
used on Linux.
HOME Set to pathnews from inn.conf.
LOGNAME Set to the news master, as determined at configure time.
PATH Set to pathbin from inn.conf, pathetc from inn.conf, and then /bin,
/usr/bin, and /usr/ucb in that order.
SHELL Set to the path to the system Bourne shell as determined by
configure (probably /bin/sh).
TMPDIR Set to pathtmp from inn.conf.
TZ Passed verbatim from inndstart's environment.
USER Set to the news master, as determined at configure time.
FILES
inn.conf
Read for pathnews, pathbin, pathrun, pathtmp, rlimitnofile,
bindaddress, and port.
pathbin/innd
The binary that is executed as innd and passed the open network socket.
pathrun
Checked for existence and the right ownership.
HISTORY
Written by Russ Allbery <rra@stanford.edu> for InterNetNews.
$Id: inndstart.8,v 1.2 1999/10/23 16:25:47 rra Exp $
SEE ALSO
inn.conf(5), innd(8)
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