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</o:shapelayout></xml><![endif]--></head><body lang=EN-AU link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Thanks for this. My mistake was:<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>iptables -A FORWARD -p tcp -d 10.0.0.2 --dport 80 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>instead of:<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT <br>iptables -A FORWARD -d 10.0.0.2 -p tcp --dport 443 -m state --state NEW -j ACCEPT<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Having separate statements for the established, related packets and new package resolved my problem<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Thanks for all your help<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Alex<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'> plug <plug-bounces@plug.org.au> <b>On Behalf Of </b>Byron Hammond via plug<br><b>Sent:</b> Thursday, 12 February 2026 9:14<br><b>To:</b> Alex H. <alex@spottedmouse.com><br><b>Cc:</b> plug@plug.org.au<br><b>Subject:</b> Re: [plug] IPTables<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Not answering the question here but I just wanted to add that you will need to have `sysctl net.ipv4.ip_forward` enabled as well if not already.<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Google something like "ip4 forward sysctl"<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Wed, 11 Feb 2026 at 18:54, Alex H. via plug <<a href="mailto:plug@plug.org.au">plug@plug.org.au</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Hi all,</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Just having some fun with iptables. I am trying to route traffic from AWS(10.0.0.1) to my local server (10.0.0.2) using wireguard. </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>I have setup a connection on vpn0 on both servers, but I am struggling a little with iptables.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>While I am experimenting I setup the following iptables rules using this script on the AWS VPN server. </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>I plan to include some of these inside the wireguard configuration once I have it all working.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>root@vpn:~# cat routeTraffic.sh</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>#!/bin/bash</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -F</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -X</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -F</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -X</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t mangle -F</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t mangle -X</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -P INPUT DROP</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -P OUTPUT DROP</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -P FORWARD ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p tcp -m tcp --dport 22 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i vpn0 -p tcp -m tcp --dport 22 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p tcp -m tcp --dport 25 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p tcp -m tcp --dport 53 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p udp -m udp --dport 53 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p tcp -m tcp --dport 80 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p tcp -m tcp --dport 443 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -p udp -m udp --dport 55107 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i vpn0 -p udp -m udp --dport 55107 -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -i ens5 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A OUTPUT -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US># 1. Redirect the incoming packet to the tunnel destination</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -A PREROUTING -p tcp --dport 53 -j DNAT --to-destination <a href="http://10.0.0.2:53" target="_blank">10.0.0.2:53</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -A PREROUTING -p udp --dport 53 -j DNAT --to-destination <a href="http://10.0.0.2:53" target="_blank">10.0.0.2:53</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination <a href="http://10.0.0.2:80" target="_blank">10.0.0.2:80</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -A PREROUTING -p tcp --dport 443 -j DNAT --to-destination <a href="http://10.0.0.2:443" target="_blank">10.0.0.2:443</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US># 2. Allow the traffic through via the FORWARD chain</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A FORWARD -p tcp -d 10.0.0.2 --dport 53 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A FORWARD -p udp -d 10.0.0.2 --dport 53 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A FORWARD -p tcp -d 10.0.0.2 --dport 80 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A FORWARD -p tcp -d 10.0.0.2 --dport 443 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -A FORWARD -j LOG</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US># 3. Apply Masquerading to ensure return traffic goes back through the server</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>iptables -t nat -A POSTROUTING -o vpn0 -j MASQUERADE</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Initially I had “iptables -P FORWARD DROP” with the hope of adding a white-list of allowed rules. However, this didn’t work. I then added the LOG statement which produces the following:</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Feb 11 10:46:19 <a href="http://vpn.host.com" target="_blank">vpn.host.com</a> kernel: IN=vpn0 OUT=ens5 MAC= SRC=10.0.0.2 DST=176.X.X.X LEN=60 TOS=0x00 PREC=0x00 TTL=63 ID=0 DF PROTO=TCP SPT=80 DPT=55784 WINDOW=64296 RES=0x00 ACK SYN URGP=0</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Feb 11 10:46:19 <a href="http://vpn.host.com" target="_blank">vpn.host.com</a> kernel: IN=vpn0 OUT=ens5 MAC= SRC=10.0.0.2 DST=176.X.X.X LEN=52 TOS=0x00 PREC=0x00 TTL=63 ID=42901 DF PROTO=TCP SPT=80 DPT=55784 WINDOW=502 RES=0x00 ACK URGP=0</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Feb 11 10:46:19 <a href="http://vpn.host.com" target="_blank">vpn.host.com</a> kernel: IN=vpn0 OUT=ens5 MAC= SRC=10.0.0.2 DST=176.X.X.X LEN=2788 TOS=0x00 PREC=0x00 TTL=63 ID=42902 DF PROTO=TCP SPT=80 DPT=55784 WINDOW=502 RES=0x00 ACK PSH URGP=0</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Feb 11 10:46:19 <a href="http://vpn.host.com" target="_blank">vpn.host.com</a> kernel: IN=vpn0 OUT=ens5 MAC= SRC=10.0.0.2 DST=176.X.X.X LEN=2788 TOS=0x00 PREC=0x00 TTL=63 ID=42904 DF PROTO=TCP SPT=80 DPT=55784 WINDOW=502 RES=0x00 ACK PSH URGP=0</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Feb 11 10:46:38 <a href="http://vpn.host.com" target="_blank">vpn.host.com</a> kernel: IN=vpn0 OUT=ens5 MAC= SRC=10.0.0.2 DST=176.X.Y.Y LEN=52 TOS=0x00 PREC=0x00 TTL=63 ID=0 DF PROTO=TCP SPT=443 DPT=59476 WINDOW=64860 RES=0x00 ACK SYN URGP=0</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Any suggestions on what FORWARD rule I need to add for this to work with FORWARD DROP ? It looks like these are the response packets which come from VPN0 and are going back to the internet on ENS5. I though the “NEW,ESTABLISHED,RELATED” statement would handle these as they are part of the response in return an accepted request.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Any thought or suggestions would be most helpful.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Kind regards</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>Alex</span><o:p></o:p></p></div></div><p class=MsoNormal>_______________________________________________<br>PLUG discussion list: <a href="mailto:plug@plug.org.au" target="_blank">plug@plug.org.au</a><br><a href="https://lists.plug.org.au/mailman/listinfo/plug" target="_blank">https://lists.plug.org.au/mailman/listinfo/plug</a><br>Committee e-mail: <a href="mailto:committee@plug.org.au" target="_blank">committee@plug.org.au</a><br>PLUG Membership: <a href="http://www.plug.org.au/membership" target="_blank">http://www.plug.org.au/membership</a><o:p></o:p></p></div></blockquote></div></div></body></html>