Re: Firewall blocking my new Debian 11 server ports 80 and 443
On 5/28/22 22:11, Tom Browder wrote:
> As the bare-iron server came from my long-time cloud provider (since
> Debian 6), incoming ports 80 and 443 are blocked.
>
> I ran my usual iptables command for new servers from them, but this
> time the default settings were different so it didn't work.
Try to flush the tables and (re)set default policies for the existing
chains.
> Output from "sudo iptables -S" before my attempt:
>
> -P INPUT ACCEPT
> -P FORWARD ACCEPT
> -P OUTPUT ACCEPT
> -N f2b-sshd
> -A INPUT -p tcp -m multiport --dports 22 -j f2b-sshd
> -A f2b-sshd -s 62.204.41.56/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 61.177.173.48/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 167.172.187.120/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 43.156.124.69/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 43.154.46.209/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 61.177.172.98/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 122.160.233.137/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -j RETURN
>
> My usual incantation and response:
>
> # sudo iptables -A IN_public_allow -p tcp -m tcp --dport 80 -m
> conntrack --ctstate NEW,UNTRACKED -j ACCEPT
> iptables: No chain/target/match by that name.
You have no chain "IN_public_allow". Probably you should create it.
> Then I tried:
>
> # sudo iptables -A INPUT -p tcp -m tcp --dport 80 -m conntrack
> --ctstate NEW,UNTRACKED -j ACCEPT
> # sudo iptables -A INPUT -p tcp -m tcp --dport 443 -m conntrack
> --ctstate NEW,UNTRACKED -j ACCEPT
It's a good practice to set input/output network interfaces.
> Again checking status:
>
> # sudo iptables -S
> -P INPUT ACCEPT
> -P FORWARD ACCEPT
> -P OUTPUT ACCEPT
> -N f2b-sshd
> -A INPUT -p tcp -m multiport --dports 22 -j f2b-sshd
> -A INPUT -p tcp -m tcp --dport 80 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 443 -m conntrack --ctstate
> NEW,UNTRACKED -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 80 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT
You have second rule for port 80/tcp, do you need it?
> -A f2b-sshd -s 62.204.41.56/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 61.177.173.48/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 167.172.187.120/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 43.156.124.69/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 43.154.46.209/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 61.177.172.98/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -s 122.160.233.137/32 -j REJECT --reject-with icmp-port-unreachable
> -A f2b-sshd -j RETURN
>
> But no open ports in spite of the output shown.
>
> I am considering moving to ufw but am reluctant due to the possibility
> of getting locked-out of my remote server. I am used to logging in
> with two separate terminals to avoid that during initial setup but
> want to make sure that is safe.
>
Kind regards
Georgi
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