Linux Efficient IP Tables to protect a Debian VPS

[Tatuy1]

I have tried several iptables to defend my server of the ddos attacks, but the result is massive kicks.

 

[rsdsebek]

You have to protect all ports - not only 7171/7172, but also ssh/sftp port and http port. I use something like this and for now it works:

iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --set --name HTTP --rsource
iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --set --name LOGIN --rsource
iptables -A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --set --name GAME --rsource
iptables -A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --set --name SSH --rsource
iptables -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP

IPTables will help you only, when the DDoS attack doesn't exceed your bandwith rate - if it does, then there is nothing you can do, besides renting a dedicated server/VPS with DDoS protection.

My best

 

[Tatuy1]

Thank you very much. You are very kind. It works.

 

[rsdsebek]

You have to protect all ports - not only 7171/7172, but also ssh/sftp port and http port. I use something like this and for now it works:

iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --set --name HTTP --rsource
iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --set --name LOGIN --rsource
iptables -A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --set --name GAME --rsource
iptables -A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --set --name SSH --rsource
iptables -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP

IPTables will help you only, when the DDoS attack doesn't exceed your bandwith rate - if it does, then there is nothing you can do, besides renting a dedicated server/VPS with DDoS protection.

My best

Whoa, there is a slight error in above, though it should work. But to be sure, here you have a proper script:

iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --set --name HTTP --rsource
iptables -A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name HTTP --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --set --name LOGIN --rsource
iptables -A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name LOGIN --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --set --name GAME --rsource
iptables -A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name GAME --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --set --name SSH --rsource
iptables -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP

 

[Tatuy1]

Thank you very much!!! but I have some problems. Look:
I tested with:
-A INPUT -j REJECT
-A FORWARD -j REJECT
To reject all other inbound - default deny unless explicitly allowed policy and the server not allowing me to connect.

And then, apparently using this configuration everything works properly:

*filter

# Allows all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0
-A INPUT -i lo -j ACCEPT
-A INPUT ! -i lo -d 127.0.0.0/8 -j REJECT

# Accepts all established inbound connections
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# Allows all outbound traffic
# You could modify this to only allow certain traffic
-A OUTPUT -j ACCEPT

# Allows HTTP, 7171, 7172 and SSH connections
-A INPUT -p tcp --dport 80 -j ACCEPT
-A INPUT -p tcp --dport 7171 -j ACCEPT
-A INPUT -p tcp --dport 7172 -j ACCEPT
-A INPUT -p tcp --dport 22 -j ACCEPT

-A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --set --name HTTP --rsource
-A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name HTTP --rsource -j DROP
-A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --set --name LOGIN --rsource
-A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name LOGIN --rsource -j DROP
-A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --set --name GAME --rsource
-A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name GAME --rsource -j DROP
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --set --name SSH --rsource
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP

# Allow ping
#  note that blocking other types of icmp packets is considered a bad idea by some
#  remove -m icmp --icmp-type 8 from this line to allow all kinds of icmp:
#  https://security.stackexchange.com/questions/22711
-A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT

# log iptables denied calls (access via 'dmesg' command)
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7

# Reject all other inbound - default deny unless explicitly allowed policy:
-A INPUT -j REJECT
-A FORWARD -j REJECT

COMMIT

What do you think?

 

[Tatuy1]

With my first test I used something like this:

-A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --set --name HTTP --rsource
-A INPUT -p tcp -m tcp --dport 80 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name HTTP --rsource -j DROP
-A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --set --name LOGIN --rsource
-A INPUT -p tcp -m tcp --dport 7171 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name LOGIN --rsource -j DROP
-A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --set --name GAME --rsource
-A INPUT -p tcp -m tcp --dport 7172 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name GAME --rsource -j DROP
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --set --name SSH --rsource
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m recent --update --seconds 1 --hitcount 15 --rttl --name SSH --rsource -j DROP
-A INPUT -j REJECT
-A FORWARD -j REJECT

But the problem is it block me all access, may be I needed:

-A INPUT -p tcp --dport 80 -j ACCEPT
-A INPUT -p tcp --dport 7171 -j ACCEPT
-A INPUT -p tcp --dport 7172 -j ACCEPT
-A INPUT -p tcp --dport 22 -j ACCEPT

But do not know if this is risky or it will give me the same problems as before. What do you recommend me my dear friend?

 

[rsdsebek]

You should throw out all rules in IPTables and leave only that rules, that I gave you. If you have almost clean Ubuntu installation, it should work flawlessly.
IPTables is completely blocking access because of those lines:

-A INPUT -j REJECT
-A FORWARD -j REJECT

because it is ordered to reject all incoming and forwarded data. Clean IPTables config, add rules from post #4 and everything should work.