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141
Firewall Security
Level Services Table
The following information is related to the Firewall options (High, Medium, and
Low) in the “Advanced Services” chapter of this manual (page
35
). The types of ser-
vices and their respective ports are listed in the two right-hand columns: the “In”
column details whether a particular service can be accessed by a user outside of the
network; and the “Out” column details whether a computer on the Gateway’s net-
work can access a particular incoming service.
For example, in the “High Security Level” section below, the http service uses port
80
. Since
no
is listed in the
In
column, a user outside the Gateway’s network can-
not access a computer on the network via the http service; in this case, no comput-
ers on the network can be used as a Web server (i.e., to host a Web site accessible to
outside users). However, since
yes is listed in the Out column, all computers on the
Gateway’s network can access the Internet via the http port.
If Basic Security is selected in the “Firewall” screen, firewall filtering is based on the
basic
NAT
firewall.
☞
Note
: This stateful packet inspection firewall is based on the
Globespan-Virata implementation and specification for release
8.2
.
High Security Level
Service Port In Out
http 80 no yes
dns 53 no yes
ftp 21 no no
telnet 23 no yes
smtp 25 no yes
pop3 110 no yes
nntp 119 no no
real audio/video 7070 no yes
icmp n/a no yes
H.323 1720 no no
T.120 1503 no no
SSH 22 no no
F