Hi.
On Sat, 16 Jan 2016 12:02:57 -0500
Steve Matzura <s...@noisynotes.com> wrote:
> Well, I thought I was doing so well. I discover now that no one,
> including me, can get into my system any more via ssh. Here are the
> current iptables rules:
>
> *filter
> :INPUT ACCEPT [0:0]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [0:0]
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -m
> hashlimit --hashlimit-upto 1/hour --hashlimit-burst 16
> --hashlimit-mode srcip --hashlimit-name ssh --hashlimit-htable-expire
> 60000 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -m
> hashlimit --hashlimit-upto 1/hour --hashlimit-burst 16
> --hashlimit-mode srcip --hashlimit-name ssh --hashlimit-htable-expire
> 60000 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -m
> hashlimit --hashlimit-upto 1/hour --hashlimit-burst 16
> --hashlimit-mode srcip --hashlimit-name ssh --hashlimit-htable-expire
> 60000 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -m
> hashlimit --hashlimit-upto 1/hour --hashlimit-burst 16
> --hashlimit-mode srcip --hashlimit-name ssh --hashlimit-htable-expire
> 60000 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -m
> hashlimit --hashlimit-upto 1/hour --hashlimit-burst 16
> --hashlimit-mode srcip --hashlimit-name ssh --hashlimit-htable-expire
> 60000 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
> -A INPUT -p tcp -m tcp --dport 22 -m conntrack --ctstate NEW -m
> hashlimit --hashlimit-upto 1/hour --hashlimit-burst 16
> --hashlimit-mode srcip --hashlimit-name ssh --hashlimit-htable-expire
> 60000 -j ACCEPT
> COMMIT
>
> What'd I do?
>
Exactly this:
iptables -F INPUT
iptables -I INPUT -p tcp --dport 22 -m conntrack --ctstate NEW \
-m hashlimit --hashlimit 1/hour --hashlimit-burst 16 \
--hashlimit-mode srcip --hashlimit-name ssh \
--hashlimit-htable-expire 60000 -j ACCEPT
iptables -I INPUT -p tcp --dport 22 --tcp-flags SYN,RST,ACK SYN \
-j DROP
Note that the order of netfilter rules is top-down (i.e. highest
matching rule plays).
So, first rule on your current list, namely:
-A INPUT -p tcp -m tcp --dport 22 --tcp-flags SYN,RST,ACK SYN -j DROP
blocked anyone from using ssh.
Reco
