IPTables Firewall Configuration in RHEL5
Firewall are two types hardware firewall and software firewall. The important work of firewall is to monitor and control the incoming and outgoing packets.
IPtables is an important firewall in linux. TCP wrapper and SELinux is also a firewall.
Package: iptables
Service: iptables
Operations
There are 3 operations iptables can do
- Accept
Allow the packet
- Drop
Drop the packet and don’t send error message to sender.
- Reject
Drop the packet and send error message to sender.
- i - incoming interface
- O - outgoing interface
- A – append (edit the previous input)
- D - Delete
- F – Flush
- L - list
- I - Input (insert)
- j - target
- P - packets
- d - destination IP
- S - source IP
- –sport -source port address
- –dport - destination port address
#vim /etc/sysconfig/iptables-config
To drop all incoming packets
By this any incoming packets will not come, but packets will be sent to others. This entry is considered as a first entry in iptables.
#iptables -I INPUT -j REJECT
#service iptables save
#service iptables restart
#chkconfig iptables ON
Stop the iptables firewall
#service iptables stop
To delete First entry
This delets the first entry in iptables.
#iptables -D INPUT 2
To view all iptables entries
#iptables -L
