catalinux / cpublaster (public) (License: GPLv3) (since 2016-02-05) (hash sha1)
This project tries to alleviate the aliasing problems of the modern CPUs.
It is a preloadable shared object.
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README:
Name: force_bind

Author: Catali(ux) M. BOIE - catab at embedromix dot ro

Start date: 2010-10-26

Description: Force binding on a specific IP and/or port.
Works with both IPv4 and IPv6.
It is useful if you have a binary application without sources
and without the possibility to configure address or port to
bind to.

License: GPLv3

How it works: force_bind is a shared object that is loaded with LD_PRELOAD and hooks 'bind' function.
Forcing an IP/port to bind to is done with environments variables.

Examples:
0. Output debug stuff in a log file (for debugging):
export FORCE_NET_VERBOSE=999
export FORCE_NET_LOG="xxx.log"
your_program_here

1. Force bind to 127.0.0.1, port 33, verbose operations:
export FORCE_NET_VERBOSE=1
export FORCE_BIND_ADDRESS_V4=127.0.0.1
export FORCE_BIND_PORT_V4=33
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

2. Force binding to 127.0.0.2, port unchanged
export FORCE_BIND_ADDRESS_V4=127.0.0.2
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

3. Force binding to ::1 (IPv6), port unchanged
export FORCE_BIND_ADDRESS_V6=::1
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

4. Changing TOS on all sockets to 30
export FORCE_NET_TOS=30
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

5. Force Keep alive to 60 seconds:
export FORCE_NET_KA=60
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

6. Force MSS to 1400
export FORCE_NET_MSS=1400
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

7. Force bandwidth to 1000 bytes/s for _all_ connections, cumulated
export FORCE_NET_BW=1000
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

8. Force bandwidth to 20000 bytes/s per socket
export FORCE_NET_BW_PER_SOCKET=20000
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
scp root@machine1:/image.iso .

9. Force REUSEADDR
export FORCE_NET_REUSEADDR=1
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

10. Force NODELAY
export FORCE_NET_NODELAY=1
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

11. Force client connections (for example 'telnet', 'ssh',
'firefox') to connect from a specified address, not the auto
selected one:
export FORCE_NET_VERBOSE=1
export FORCE_BIND_ADDRESS_V4=127.0.0.2
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

12. Set a FLOWINFO (flow label + class) for a client connection:
export FORCE_NET_VERBOSE=1
export FORCE_NET_FLOWINFO=0x7812345 # class 0x78, label 0x12345
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here
A tcpdump of a connection will look like:
00:00:00:00:00:00 > 00:00:00:00:00:00, ethertype IPv6 (0x86dd),
length 94: (class 0x78, flowlabel 0x12345, hlim 64, next-header TCP (6) payload length: 40)
::1.56981 > ::1.krb524: Flags [S], cksum 0x0030 (incorrect -> 0x91cf),
seq 1154252590, win 32752, options [mss 16376,sackOK,TS val 28395104 ecr 0,nop,wscale 4], length 0

13. Force FWMARK on a connection (only root is allowed):
export FORCE_NET_VERBOSE=1
export FORCE_NET_FWMARK=0x1234
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
your_program_here

14: Force priority (between 0 and 6 for non-root users). You can
use 'tc' command from iproute to set-up 'prio' qdisc and to
assign prio to queues:
# 0. setup
export FORCE_NET_VERBOSE=1
export LD_PRELOAD=${LD_PRELOAD}:/usr/lib/force_bind.so
# 1. Make sure you have a 'prio' qdisc attached to eth0, for example:
tc qdisc add ev eth0 root handle 1: prio
# 2. Assign applications to classed (bands):
export FORCE_NET_PRIO=6 # interactive, band 0
your_voip_program_here
export FORCE_NET_PRIO=0 # best effort, band 1
your_mail_program_here
export FORCE_NET_PRIO=2 # bulk, band 2
your_remote_backup_program_here
# 3. Run tc statistics so you can see the classification:
tc -s class show dev eth0


Installation:
- ./configure
- make
- make install
Hints:
Before first commit, do not forget to setup your git environment:
git config --global user.name "your_name_here"
git config --global user.email "your@email_here"

Clone this repository using HTTP(S):
git clone https://rocketgit.com/user/catalinux/cpublaster

Clone this repository using ssh (do not forget to upload a key first):
git clone ssh://rocketgit@ssh.rocketgit.com/user/catalinux/cpublaster

Clone this repository using git:
git clone git://git.rocketgit.com/user/catalinux/cpublaster

You are allowed to anonymously push to this repository.
This means that your pushed commits will automatically be transformed into a merge request:
... clone the repository ...
... make some changes and some commits ...
git push origin main