owampd.limits
Section: File Formats (5)
Updated: $Date: 2006-11-07 00:54:55 -0500 (Tue, 07 Nov 2006) $
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NAME
owampd.limits - One-way latency server policy configuration file
DESCRIPTION
The owampd.limits file is used to define the policy configuration
for the owampd program. It allows the system administrator to
allocate the resources in a variety of ways.
There are two parts to the policy configuration:
- Authentication
-
Who is making the request? This can be very specific to an individual
user or it can be more general in that the connection is coming from
some particular network.
- Authorization
-
Now that the connection has been generally identified, what will owampd
allow it to do?
The authentication is done by assigning a limitclass to each new
connection as it comes in. Each limitclass has a set of limits
associated with it. The limitclasses are hierarchical, so a connection
must pass the limit restrictions of the given limitclass as well as all
parent classes.
Within the owampd.limits file, assign lines are used to
assign a limitclass to a given connection. limit lines are
used to define a limitclass and set the limits associated with that
limitclass. The file is read sequentially, and it is not permitted
to use a limitclass before it is defined using a limit line.
The format of this file is:
-
- *
-
Comment lines are any line where the first non-whitespace character is '#'.
These lines are counted to return line numbers in error
messages but are otherwise ignored by owampd.
- *
-
Lines may be continued using the semi-standard '\' character followed
immediately by a newline. This is the only valid place for the '\'
character. If it is found elsewhere a syntax error is reported.
- *
-
Blank lines are treated as comment lines.
- *
-
All other lines must conform to the syntax of a limit line or
an assign line.
CONFIGURATION OPTIONS
- limit
-
This directive is used to define the limitclass hierarchy. It
defines the limitclassname as well as the limits associated with
that class. A limitclassname may only be defined once. The
format of the limit directive is:
-
limit limitclassname with
limtype=value[,limtype=value]*
limitclassname defines the name of the class with the given
limits. Whitespace is used as a separator but is otherwise
ignored. limitclassname may be used as a directory name component
within owampd, so take care not to use characters that would be
invalid. (i.e. '*' or '/' would be particularly bad.)
limtype and value indicate the particular type of limit and
value to apply to this limitclass. The available settings for
limtype are:
limtype | valid values | default
|
|
|
|
bandwidth | integer (bits/sec) | 0 (unlimited)
|
disk | integer (bytes) | 0 (unlimited)
|
delete_on_fetch | on/off | off
|
parent | already defined limitclassname | null
|
- allow_open_mode
-
This limit is only useful if the class is assigned
to a netmask. It is used to limit specific IP/netmask identities
to only encrypted or authenticated mode transactions or
to allow open mode.
- bandwidth
-
Maximum amount of bandwidth to allow limitclass
to use concurrently in all one-way tests. 0 indicates unlimited
by policy, but remember this is checked all the way to
the root of the hierarchy. (If you want an unlimited limitclass, your
root must be unlimited as well as the whole path down
to the given limitclass.)
- disk
-
Maximum amount of disk space to allow a given limitclass
to consume. This defines a limit that is used during the authorization
of a given test request (this is a soft limit). If the estimated file size
for a test request is larger than the disk limit, the test request will
be denied.
Additionally, because a given test can actually consume
more space than this estimate due to duplicate packets, the diskfudge
factor is used upon the completion of a test to decide if the file should
be kept. If the new file causes the disk space used by a limitclass
to be larger than the disk limit
multiplied by the diskfudge factor (this defines the hard limit)
the file will be deleted.
- delete_on_fetch
-
Indicates that buffered data files should be automatically be deleted
by the owampd server as soon as they are fetched.
- parent
-
The first limit line cannot have a parent since
none have been defined yet. As such, the first
line defines the root of your class hierarchy.
All remaining limit lines MUST assign a parent.
(It is hierarchical, after all.)
- assign
-
The assign directive is used to assign a limitclass to a
given connection. Basically, it authenticates the connection.
The format of the assign directive is:
-
assign authtype [args] limitclassname
authtype identifies the type of authentication being used. Whitespace
is used as a separator but is otherwise ignored. limitclassname must
have been previously defined with the limit directive earlier
in the file.
The available settings for authtype are:
- default
-
Used if no other assignment matches. It takes no args.
- net subnet
-
Assign a specific subnet to a given limitclass.
subnet must be specified using VLSM notation (IP/nbits).
The only arg is the subnet.
For example:
-
- 127.0.0.1/32
-
would match only the loopback IPv4 address.
- ::1/128
-
would match only the loopback IPv6 address.
- 192.168.1.0/24
-
would match all hosts on the 192.168.1.XXX network.
There must be no set bits in the non-masked portion of the address part
of the subnet specification. i.e., 192.168.1.1/24 would be
an invalid subnet due to the bit set in the fourth octet.
- user user
-
Assign a specific user to a given limitclass.
The user must be defined in the owampd.pfs file.
AUTHENTICATION PROCESS
owampd determines if it should allow a connection from
the client based upon the authentication mode of the request and the source
IP address of the connection. If the client connection is in authenticated or
encrypted mode, the daemon does not do any filtering based upon the
source address of the connection. (See the -A option to owping
and the authmode option in owampd.conf.)
In these modes owampd simply uses the identity of the
connection to determine the limitclass limits. If the connection
is made in open mode, then owampd first uses the source address to
determine if owampd should allow an open mode connection from
that subnet at all. (This is
the purpose of the allow_open_mode limtype described above.)
If open mode is allowed from this subnet, then the limitclass
is determined by the closest subnet match defined by the assign net
lines in the owampd.limits file.
EXAMPLES
An initial limit line might look like:
-
-
- limit root with \
bandwidth=900m, \
disk=2g, \
allow_open_mode=off
This would create a limitclass named root. Because no
parent is
specified, this must be the first limitclass defined in the
file. This limitclass has very liberal limits (900m limit on
bandwidth, and 2 GB of disk space). However, open mode authentication
is not enabled for
this limitclass, so the connections that get these limits must
successfully authenticate using an AES key derived from the pass-phrase
in the owampd.pfs file.
If an administrator also wants to create a limitclass that is used
to deny all requests, they might add:
-
-
- limit jail with \
parent=root, \
bandwidth=1, \
disk=1, \
allow_open_mode=off
This would create a limitclass named jail. Because the limits
for bandwidth and disk are so low, virtually all tests will be denied.
allow_open_mode is off, so initial connections that are not in
authenticated or encrypted mode will be dropped immediately.
(It would not make much sense to assign a user identity to this
limitclass. If you don't want connections from a particular user
identity the best thing to do is to remove that user from
the owampd.pfs file.)
If the administrator wanted to allow a limited amount of open tests, they
could define a limitclass like:
-
-
- limit open with \
parent=root, \
bandwidth=10k, \
disk=10m, \
allow_open_mode=on
This could be used to allow testing by random connections.
It limits those tests to 10 kilobits of bandwidth and 10 Mbytes of
buffer space.
Now, these three limitclasses might be assigned to specific connections
in the following ways:
-
# default open
assign default open
# badguys subnet
assign net 192.168.1.0/24 jail
# network admins
assign user joe root
assign user jim root
assign user bob root
This set of assign lines specifically denies access from any
open mode connection from the badguys subnet. It specifically
allows access to authenticated or encrypted mode transactions that can
authenticate as the identities joe jim or bob (even from
the badguys subnet). All other connections would match the
assign default rule and get the limits associated with the open
limitclass.
SEE ALSO
owping(1), owampd(8), owampd.limits(5), owampd.pfs(5), aespasswd(1),
and the http://e2epi.internet2.edu/owamp/ web site.
ACKNOWLEDGMENTS
This material is based in part on work supported by the National Science
Foundation (NSF) under Grant No. ANI-0314723. Any opinions, findings and
conclusions or recommendations expressed in this material are those of
the author(s) and do not necessarily reflect the views of the NSF.
Index
- NAME
-
- DESCRIPTION
-
- CONFIGURATION OPTIONS
-
- AUTHENTICATION PROCESS
-
- EXAMPLES
-
- SEE ALSO
-
- ACKNOWLEDGMENTS
-
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Time: 17:52:42 GMT, January 23, 2009