Using lsof to list all of the TCP and UDP listening sockets.
lsof - list open files
Detecting Listening Network Ports
One of the most important tasks is to detect and close network ports that are not needed.
To get a list of listening network ports (TCP and UDP sockets), you can run the following command:
netstat -tulp
Running a port scan from another server. (make sure that you have permissions to probe a machine):
How to turn on spoof protection
To turn on spoof protection, run a simple bash script:
Sysctl Hardening Modifies kernel operating values to strengthen TCP/IP stack against various attacks including syn floods.
sysctl.conf is a simple file containing sysctl values to be read in and set by sysctl(8)
EXAMPLES
TCP_SYNCookies protection
A SYN-flood attack has the ability to bring the network aspect of your linux box to a snail like crawl. TCP_SYNCookies protection attempts to stop this from taking a heavy toll on the machine. To enable tcp_syncookies protection, use the following command:
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
If it’s not enabled, there isn’t much you can do other than build a new kernel and reboot and use it.
Find if ssl certificate and key are paired correctly.
To view the contents of a certificate:
To view the contents of a private key:
If the modulus number and exponent of the cert and key match, they are paired correctly. If not, they are mismatched and apache will not start with ssl enabled.
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