Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007 Installation Manual page 843

proxy server between the hosts of the internal network and the Internet. Masquerad-
ing is not needed for services a proxy server provides.
FW_MASQ_NETS (masquerading)
Specify the hosts or networks to masquerade, leaving a space between the individ-
ual entries. For example:
FW_MASQ_NETS="192.168.0.0/24 192.168.10.1"
FW_PROTECT_FROM_INT (firewall)
Set this to yes to protect your firewall host from attacks originating in your internal
network. Services are only available to the internal network if explicitly enabled.
Also see FW_SERVICES_INT_TCP and FW_SERVICES_INT_UDP.
FW_SERVICES_EXT_TCP (firewall)
Enter the TCP ports that should be made available. Leave this blank for a normal
workstation at home that should not offer any services.
FW_SERVICES_EXT_UDP (firewall)
Leave this blank unless you run a UDP service and want to make it available to
the outside. The services that use UDP include include DNS servers, IPsec, TFTP,
DHCP and others. In that case, enter the UDP ports to use.
FW_SERVICES_INT_TCP (firewall)
With this variable, define the services available for the internal network. The nota-
tion is the same as for FW_SERVICES_EXT_TCP, but the settings are applied to
the internal network. The variable only needs to be set if
FW_PROTECT_FROM_INT is set to yes.
FW_SERVICES_INT_UDP (firewall)
See FW_SERVICES_INT_TCP.
After configuring the firewall, test your setup. The firewall rule sets are created by en-
tering SuSEfirewall2 start as root. Then use telnet, for example, from an
external host to see whether the connection is actually denied. After that, review /var/
log/messages, where you should see something like this:
Mar 15 13:21:38 linux kernel: SFW2-INext-DROP-DEFLT IN=eth0
OUT= MAC=00:80:c8:94:c3:e7:00:a0:c9:4d:27:56:08:00 SRC=192.168.10.0
DST=192.168.10.1 LEN=60 TOS=0x10 PREC=0x00 TTL=64 ID=15330 DF PROTO=TCP
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