Linux Firewall notes


>> Allow port 80 ONLY to private interface for Cloud Load Balancer
-A INPUT -i eth1 -p tcp -m conntrack --ctstate NEW -m tcp --dport 80 -j ACCEPT

>> Block whole subnet
# iptables -I INPUT -s -j DROP

>> Allow specific IP only
iptables -I INPUT -p tcp -s YourIP --dport 22 -j ACCEPT

>> Delete rules

iptables -vnL --line-numbers

iptables -D <chain> /et<rule_number>
iptables -D INPUT 4

-A INPUT -s <SOURCE_NETWORK/32> -p tcp -m tcp --dport 21 -m comment --comment "FTP port open" -j ACCEPT
-A INPUT -s <SOURCE_NETWORK/32> -p tcp -m multiport --dports 60000:65000 -m comment --comment "FTP passive mode ports" -j ACCEPT



service ufw status

ufw allow 80

ufw allow from <IP> to any port <port>

>> Allow network range
ufw allow

>> Delete rule
ufw status numbered
ufw delete <rule_number>

>> Allow port 80 only on eth1
ufw allow in on eth1 to [eth1 ip addr] port 80 proto tcp
# ufw allow from <SOURCE_IP>&nbsp;to any port 25
Rule added

# ufw delete allow from <SOURCE_IP> to any port 25
Rule deleted

ufw insert 1 allow from <ip address>

ufw deny from <ip address>
ufw deny from <ip address/24>


CENTOS / RH – Firewalld

Saved rules in: /etc/sysconfig/iptables

firewall-cmd --permanent --zone=public --add-service=http
firewall-cmd --permanent --zone=public --add-service=https
firewall-cmd --reload

firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<SOURCE_IP>" port port="10000" protocol="tcp" accept'

firewall-cmd --reload

firewall-cmd --list-all

firewall-cmd --add-service http --permanent
firewall-cmd --add-service https --permanent
systemctl restart firewalld.service
firewall-cmd --list-services

>> Add manual rule in firewalld

firewall-cmd --permanent --direct --add-rule ipv4 filter INPUT 0 -s -m comment --comment "NFS Network" -j ACCEPT

>> Remove manual added rule in firewalld
vim /etc/firewalld/direct.xml