Linux Security

Anything about security on linux. When topics are already covered in other pages, give links to them.

Setting umask

Default setting for umask on Ubuntu / Debian is 022, meaning all created files / folders are by default world readable.

To change the defaults (see [1]) to 027:

Add to /etc/sudoers:

Defaults umask = 0027
Defaults umask_override

Edit /etc/login.defs:

UMASK       027

Firewall

With UFW

TBC

With iptables

List the firewall rules

iptables -L

Stop the firewall:

iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT