User Guide
49
Packet Filter Policies
NTP
Network Time Protocol (NTP) is a protocol built on TCP/IP that controls local timekeeping. It
synchronizes computer clocks with other clocks located on the Internet.
Characteristics
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Internet Protocol(s): TCP, UDP
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Port Number(s): TCP 123 , UDP 123
OSPF
Open Shortest Path First (OSPF) is a routing protocol developed for IP networks based on the link-state
algorithm. OSPF is quickly replacing the use of RIP on the Internet because it gives smaller, more
frequent updates to routing tables and makes networks more stable.
Characteristics
•
Internet Protocol(s): OSPF
•
Port Number(s): Any port
pcAnywhere
pcAnywhere is a software application used to get remote access to Windows computers. To enable this
protocol, add the PCAnywhere policy. Then, allow access from the hosts on the Internet that must get
access to internal pcAnywhere servers, and to the internal pcAnywhere servers.
pcAnywhere is not a very secure policy and can put network security at risk, because it allows traffic
through the firewall without authentication. Also, your pcAnywhere server can receive denial-of-
service attacks. We recommend that you use VPN options to give more security.
Characteristics
•
Internet Protocol(s): UDP, TCP
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Port Number(s): UDP 22, TCP 5631, UDP 5632, TCP 65301
Ping
You can use ping to confirm if a host can be found and is operating on the network. To find DOS-based
or Windows-based traceroute packets, configure a ping policy.
Outgoing ping is a good tool for troubleshooting. We do not recommend you allow ping connections
to your trusted network.
Characteristics
•
Internet Protocol(s): ICMP (type: 8, code: 255)
