Limit BitTorrent Sync connections to a specific network

Question

Is it possible to limit BitTorrent Sync connections to a a specific network using the client software? Right now the closest I can come up with would be IP limitations imposed on each client using a firewall. This seems like it would work fine, except for if any client somehow ventures outside those firewall restrictions.

Answer 1

If you are using Linux, iptables has a match called "owner" where you can apply certain rules based off the UID or GID of the process sending the data.

For instance:

• Put the IP's or CIDR network addresses in a file (one entry per line)
• Create a new user called btsync

• Run the following:

  #/bin/bash
  
  RESTRICTED_IP_FILE="/some/file"
  
  sudo iptables -N btsync_filter
  sudo iptables -I OUTPUT -m owner --uid-owner btsync -j btsync_filter
  
  while read ip; do 
      [[ -n "$ip" ]] && sudo iptables -A btsync_filter -d $ip -j DROP
  done < $RESTRICTED_IP_FILE
  
  sudo -u btsync btsync
  

This will run btsync as the user btsync and all packets from that process that are going to a restricted IP will be dropped.