I'm very new to Linux and bash. I'm working on a homelab (machine a) project.
My ultimate goal is to set up Nginx on my server and connect externally (machine c) to Docker apps File Browser, possibly Sonarr and a few other services. I'm following this video > LINK
I cannot port forward on my rubbish UK BT router so I have opted for a VPS (machine b). Mainly because I didn't want to have to deal with bandwidth limitations with Cloudflare or Oracle zero tier.
I have been looking for the right iptables command for the port forwarding. I have landed on the below.
sudo iptables -t nat -A PREROUTING -p tcp --dport 80 (Machine b) -j DNAT --to-destination x.x.x.x:18880 (machine a)
sudo iptables -t -A POSTROUTING -p tcp x.x.x.x(machine a) --dport 18880 -j SNAT to --to-source x.x.x.x (machine b)
sudo iptables -A FORWARD -p tcp -d x.x.x.x (machine a) --dport 18880 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
What I've done so far:
- I've enabled ipv4 port forwarding
- Flushed the nat table
- Initially, I enabled ufw but disabled it after I discovered iptables. - I also reset the ufw and there are no rules.
When I view the iptables rules this is what I get. Although I ran the prerouting command but it didn't appear.
If you have any suggestions feel free. This is still very new to me.
TIA
iptables-save output (shows all tables):
# Generated by iptables-save v1.8.4 on Mon Nov 6 20:37:01 2023
*filter
:INPUT DROP [54923:2610101]
:FORWARD DROP [120:5736]
:OUTPUT ACCEPT [402:21052]
:ts-forward - [0:0]
:ts-input - [0:0]
:ufw-after-forward - [0:0]
:ufw-after-input - [0:0]
:ufw-after-logging-forward - [0:0]
:ufw-after-logging-input - [0:0]
:ufw-after-logging-output - [0:0]
:ufw-after-output - [0:0]
:ufw-before-forward - [0:0]
:ufw-before-input - [0:0]
:ufw-before-logging-forward - [0:0]
:ufw-before-logging-input - [0:0]
:ufw-before-logging-output - [0:0]
:ufw-before-output - [0:0]
:ufw-logging-allow - [0:0]
:ufw-logging-deny - [0:0]
:ufw-not-local - [0:0]
:ufw-reject-forward - [0:0]
:ufw-reject-input - [0:0]
:ufw-reject-output - [0:0]
:ufw-skip-to-policy-forward - [0:0]
:ufw-skip-to-policy-input - [0:0]
:ufw-skip-to-policy-output - [0:0]
:ufw-track-forward - [0:0]
:ufw-track-input - [0:0]
:ufw-track-output - [0:0]
:ufw-user-forward - [0:0]
:ufw-user-input - [0:0]
:ufw-user-limit - [0:0]
:ufw-user-limit-accept - [0:0]
:ufw-user-logging-forward - [0:0]
:ufw-user-logging-input - [0:0]
:ufw-user-logging-output - [0:0]
:ufw-user-output - [0:0]
-A INPUT -j ts-input
-A INPUT
-A INPUT -j ufw-before-logging-input
-A INPUT -j ufw-before-input
-A INPUT -j ufw-after-input
-A INPUT -j ufw-after-logging-input
-A INPUT -j ufw-reject-input
-A INPUT -j ufw-track-input
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A FORWARD -j ts-forward
-A FORWARD -j ufw-before-logging-forward
-A FORWARD -j ufw-before-forward
-A FORWARD -j ufw-after-forward
-A FORWARD -j ufw-after-logging-forward
-A FORWARD -j ufw-reject-forward
-A FORWARD -j ufw-track-forward
-A OUTPUT -j ufw-before-logging-output
-A OUTPUT -j ufw-before-output
-A OUTPUT -j ufw-after-output
-A OUTPUT -j ufw-after-logging-output
-A OUTPUT -j ufw-reject-output
-A OUTPUT -j ufw-track-output
-A ts-forward -i tailscale0 -j MARK --set-xmark 0x40000/0xff0000
-A ts-forward -m mark --mark 0x40000/0xff0000 -j ACCEPT
-A ts-forward -s 100.64.0.0/10 -o tailscale0 -j DROP
-A ts-forward -o tailscale0 -j ACCEPT
-A ts-input -s 100.105.39.150/32 -i lo -j ACCEPT
-A ts-input -s 100.115.92.0/23 ! -i tailscale0 -j RETURN
-A ts-input -s 100.64.0.0/10 ! -i tailscale0 -j DROP
-A ts-input -i tailscale0 -j ACCEPT
-A ufw-after-input -p udp -m udp --dport 137 -j ufw-skip-to-policy-input
-A ufw-after-input -p udp -m udp --dport 138 -j ufw-skip-to-policy-input
-A ufw-after-input -p tcp -m tcp --dport 139 -j ufw-skip-to-policy-input
-A ufw-after-input -p tcp -m tcp --dport 445 -j ufw-skip-to-policy-input
-A ufw-after-input -p udp -m udp --dport 67 -j ufw-skip-to-policy-input
-A ufw-after-input -p udp -m udp --dport 68 -j ufw-skip-to-policy-input
-A ufw-after-input -m addrtype --dst-type BROADCAST -j ufw-skip-to-policy-input
-A ufw-after-logging-forward -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "
-A ufw-after-logging-input -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "
-A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-forward -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A ufw-before-forward -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A ufw-before-forward -p icmp -m icmp --icmp-type 12 -j ACCEPT
-A ufw-before-forward -p icmp -m icmp --icmp-type 8 -j ACCEPT
-A ufw-before-forward -j ufw-user-forward
-A ufw-before-input -i lo -j ACCEPT
-A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-input -m conntrack --ctstate INVALID -j ufw-logging-deny
-A ufw-before-input -m conntrack --ctstate INVALID -j DROP
-A ufw-before-input -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 12 -j ACCEPT
-A ufw-before-input -p icmp -m icmp --icmp-type 8 -j ACCEPT
-A ufw-before-input -p udp -m udp --sport 67 --dport 68 -j ACCEPT
-A ufw-before-input -j ufw-not-local
-A ufw-before-input -d 224.0.0.251/32 -p udp -m udp --dport 5353 -j ACCEPT
-A ufw-before-input -d 239.255.255.250/32 -p udp -m udp --dport 1900 -j ACCEPT
-A ufw-before-input -j ufw-user-input
-A ufw-before-output -o lo -j ACCEPT
-A ufw-before-output -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-output -j ufw-user-output
-A ufw-logging-allow -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW ALLOW] "
-A ufw-logging-deny -m conntrack --ctstate INVALID -m limit --limit 3/min --limit-burst 10 -j RETURN
-A ufw-logging-deny -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK] "
-A ufw-not-local -m addrtype --dst-type LOCAL -j RETURN
-A ufw-not-local -m addrtype --dst-type MULTICAST -j RETURN
-A ufw-not-local -m addrtype --dst-type BROADCAST -j RETURN
-A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j ufw-logging-deny
-A ufw-not-local -j DROP
-A ufw-skip-to-policy-forward -j DROP
-A ufw-skip-to-policy-input -j DROP
-A ufw-skip-to-policy-output -j ACCEPT
-A ufw-track-output -p tcp -m conntrack --ctstate NEW -j ACCEPT
-A ufw-track-output -p udp -m conntrack --ctstate NEW -j ACCEPT
-A ufw-user-input -p tcp -m tcp --dport 80 -j ACCEPT
-A ufw-user-input -p udp -m udp --dport 80 -j ACCEPT
-A ufw-user-input -p tcp -m tcp --dport 443 -j ACCEPT
-A ufw-user-input -p udp -m udp --dport 443 -j ACCEPT
-A ufw-user-limit -m limit --limit 3/min -j LOG --log-prefix "[UFW LIMIT BLOCK] "
-A ufw-user-limit -j REJECT --reject-with icmp-port-unreachable
-A ufw-user-limit-accept -j ACCEPT
COMMIT
# Completed on Mon Nov 6 20:37:01 2023
# Generated by iptables-save v1.8.4 on Mon Nov 6 20:37:01 2023
*nat
:PREROUTING ACCEPT [23534:1179042]
:INPUT ACCEPT [5148:292118]
:OUTPUT ACCEPT [257:18587]
:POSTROUTING ACCEPT [257:18587]
:ts-postrouting - [0:0]
-A PREROUTING -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.1.209:1880
COMMIT
# Completed on Mon Nov 6 20:37:01 2023
iptablesoutput is incomplete. Installpastebinit, then usesudo iptables-save | pastebinitand put the link in a comment here for us to see the full ruleset of IPTables (NAT rules don't show in standardiptablesoutput). Note also what you're doing is NAT, not Reverse Proxying. What is your intended goal here?