MWRPFrottleDevDiscussion

daemon 1
verbose 1
logfile /var/log/frottle.log
clientstatsfile /var/www/html/frottle/client.html
masterinfofile /var/www/html/frottle/master.html
#MODE-CLIENT  INTERFACE  MASTER IP       PRIORITY PORTS  PORT    QUEUESIZE
client        wlan0      10.10.144.49    22,53           999     100
client        eth0       10.10.255.1     22,53,5001      -       100
client        eth2       10.10.129.1     -               1001

#                        CLIENTMODE          
#MODE-MASTER  INTERFACE  (SELF/CLIENT/NONE)  TIMEOUT POLLPARAMS
master        eth1       self                100     60000,10,6000,7,5000,5,4000
master        wlan1      -                   200

This patch contains a number of small changes to frottle 0.2.1

To install:

   apply patch from inside the frottle directory
   patch -p1 < path-to-patch/frottle-0.2.1-mwPre0.1.diff

The changes were done in order to make configuring frottle easier in a
multi-interface environment.

1. New command line arguments

 frottle master | client <interface> <port>

 --mode master | client
   This argument is used to select an alternative configuration file:
       master  /etc/frottle-master.conf
       client  /etc/fottle-client.conf
   Mode parameters still need to be set in the configuration file.
  
 --interface <interface>
   This argument allows the interface specified in the configuration file
   to be overridden.

 --port <port>
   This argument allows the Master port specified in the configuration file
   to be overriden. Care should be used with this argument as only a correct
   combination of Master IP addr and Master port will allow a client to
   connect to a master instance.

2. Support for re-named binary.

If the frottle binary is launched using the name frottlemaster
either renamed, hard or soft linked then it will default to -mode master

3. New configuration file options

#pidFile
#pidfile /var/run/frottle.pid

If this option is defined the process ID will be written to the file specified.
No checking for multiple instance is done at this stage. If the file already
exists then the pid will be added to the file. On shutdown the file is unlinked
(this will be a problem in the case of multiple instances).
pre and post scripts are supported for Master and Client configurations.
The specified script will be called with the following arguments:

 scriptname interface masterport
 

#Master pre-script
#masterprescript /usr/local/frottle_master_pre.sh

#Client pre-script
#clientprescript /usr/local/frottle_client_pre.sh

#Master post-script
#masterpostscript /usr/local/frottle_master_post.sh

#Client post-script
#clientpostscript /usr/local/frottle_client_post.sh

#Client re-register timeout
#clientreregister 10

The client retry time was hard coded. this is now configurable. If the client
does not hear from the master after this time it assumes it has been dropped
and will try to re-connect. 10 was the hard coded default, may be a little high.

#Client timeout
#clienttimeout 60

The client will timeout if nothing is hear from the master after this time.
It will fall out of the frottle configuration. This was hard coded and
is now configurable.

#Client link speed
#clientlink 0

In some cases the IOCTL that is used to return the link speed will fail in
the client. This will leave the client at the fastest linkspeed default. This
may not be desirable. Setting clientlink to non zero ( set to the link rate )
it will override the internal default. Use this to reduce the TX window in
clients on a slow link to prevent them hogging the available time.

4. Bug fixes

Bandwidth allocation was testing for link speed >=5 else ==2 else other.
This was changed to >=5 else >=2 else other.

Errors in the management of the client concetion state meant that once a
conncetion was timed out it would repeatedly go through flushing the queued
packets when this was not necessary.

5. Known Issues
Need some more work on the thread join for multiple interface support. This is
only on shutdown and sems to work Ok.

Config file parsing logic has a error where it is looking for blank lines.
This is cosmetic but should be fixed at some stage.

The link speed setting from the wireless interface divides the value returned
from the IOCTL cal by 1000000. It may be it should be divided by 10,000,000.
As it stands if the value returned is 54,000,000 then it is going to be 54.
In the code the time slice is allocated according to >=5, >=2, <2. As it
stands all links will be in the top allocation category. ( this needs checking)

QUEUE is a special target, which queues the packet for userspace processing. For this to be useful, two further components are required:

• a "queue handler", which deals with the actual mechanics of passing packets between the kernel and userspace; and
• a userspace application to receive, possibly manipulate, and issue verdicts on packets.

The standard queue handler for IPv4 iptables is the ip_queue module, which is distributed with the kernel and marked as experimental.

The following is a quick example of how to use iptables to queue packets for userspace processing:


With this rule, locally generated outgoing ICMP packets (as created with, say, ping) are passed to the ip_queue module, which then attempts to deliver the packets to a userspace application. If no userspace application is waiting, the packets are dropped.

To write a userspace application, use the libipq API. This is distributed with iptables. Example code may be found in the testsuite tools (e.g. redirect.c) in CVS.

The status of ip_queue may be checked via:


The maximum length of the queue (i.e. the number packets delivered to userspace with no verdict issued back) may be controlled via:


The default value for the maximum queue length is 1024. Once this limit is reached, new packets will be dropped until the length of the queue falls below the limit again. Nice protocols such as TCP interpret dropped packets as congestion, and will hopefully back off when the queue fills up. However, it may take some experimenting to determine an ideal maximum queue length for a given situation if the default value is too small.

ipq_packet_msg structure
Just a dump of the ipq_packet_msg structure.

ipq_packet_msg structure defined in /usr/include/linux/netfilter_ipv4/ip_queue.h:


typedef struct ipq_packet_msg {

   unsigned long packet_id; /* ID of queued packet */
   unsigned long mark; /* Netfilter mark value */
   long timestamp_sec; /* Packet arrival time (seconds) */
   long timestamp_usec; /* Packet arrvial time (+useconds) */
   unsigned int hook; /* Netfilter hook we rode in on */
   char indev_nameIFNAMSIZ; /* Name of incoming interface */

   unsigned short hw_protocol; /* Hardware protocol (network order) */
   unsigned short hw_type; /* Hardware type */
   unsigned char hw_addrlen; /* Hardware address length */
   unsigned char hw_addr8; /* Hardware address */
   size_t data_len; /* Length of packet data */
   unsigned char payload0; /* Optional packet data */

} ipq_packet_msg_t;

Version 7 (old) modified Mon, 26 Jul 2021 12:49:29 +0000 by Dan