This repo is fork of Linux ISG project from Oleg A. Arkhangelsky.

It is based on a non-original copy of source code recovered from old archive. Previously this code was published under GNU License so there is no problem to restore it in public.

• Restore (write from scratch) match userspace library because it was lost during recovery
• Linux kernel version 4.19+ is supported

• The code is really full of global spinlocks and currently do not scale well on multi-CPU servers. I will try to rewrite it with a new lockless techniques in future.
• A userspace daemon should be rewritten because perl is not fast enought in case of creating lots of new sessions per second.
• IPv6 support is fully absent. I think that shoud be fixed.

cd /opt
git clone https://github.com/junjunk/lisg.git

apt install -y linux-headers-$(uname -r) iptables-dev build-essential
OR
apt-get -y install linux-headers-$(uname -r) iptables-dev build-essential

cpan install Net::Radius::Packet

chmod 777 /opt/lisg/kernel/configure && /opt/lisg/kernel/configure && make clean && make && make install
modprobe ipt_ISG
echo ipt_ISG >> /etc/modules

traffic is not dropping during the authorization of freeradius:
modprobe ipt_ISG tg_deny_action=1

Use iptables to setup rules in FORWARD chain to specify how to init session

iptables -A FORWARD -s 192.0.0.0/24 -j ISG --session-init
iptables -A FORWARD -d 192.0.0.0/24 -j ISG

This commands will advise ISG module to initiate session for every IP address from 192.0.0.0/24 network and to policy traffic to 192.0.0.0/24 network in case of active session

uncomment on the config.pl

#$cfg{unauth_service_name_list} = [ "AREDIR" ];

#$cfg{srv}{REDIR}{type} = "tagger";

#$cfg{srv}{REDIR}{traffic_classes} = [ "ALL_OTHER" ];

-A PREROUTING -m isg --service-name REDIR -p tcp -m multiport --dports 80,443 -j DNAT --to-destination 192.168.0.1

This command will make DNAT for every HTTP packet that found in ISG with service REDIRECT. Possible usage to redirect to authorization web-site.

Additional documentation can be found by your favorite search engine