Chapter 10 Firewalls
P-660HWP-Dx User’s Guide
40
10.4.2.1 ICMP Vulnerability
ICMP is an error-reporting protocol that works in concert with IP. The following ICMP types
trigger an alert:
10.4.2.2 Illegal Commands (NetBIOS and SMTP)
The only legal NetBIOS commands are the following - all others are illegal.
All SMTP commands are illegal except for those displayed in the following tables.
10.4.2.3 Traceroute
Traceroute is a utility used to determine the path a packet takes between two endpoints.
Sometimes when a packet filter firewall is configured incorrectly an attacker can traceroute
the firewall gaining knowledge of the network topology inside the firewall.
Often, many DoS attacks also employ a technique known as "
IP Spoofing
" as part of their
attack. IP Spoofing may be used to break into systems, to hide the hacker's identity, or to
magnify the effect of the DoS attack. IP Spoofing is a technique used to gain unauthorized
access to computers by tricking a router or firewall into thinking that the communications are
coming from within the trusted network. To engage in IP spoofing, a hacker must modify the
packet headers so that it appears that the packets originate from a trusted host and should be
allowed through the router or firewall. The P-660HWP-Dx blocks all IP Spoofing attempts.
10.5 Stateful Inspection
With stateful inspection, fields of the packets are compared to packets that are already known
to be trusted. For example, if you access some outside service, the proxy server remembers
things about your original request, like the port number and source and destination addresses.
This “remembering” is called
saving the state.
When the outside system responds to your
request, the firewall compares the received packets with the saved state to determine if they
Table 56
ICMP Commands That Trigger Alerts
5
REDIRECT
13
TIMESTAMP_REQUEST
14
TIMESTAMP_REPLY
17
ADDRESS_MASK_REQUEST
18
ADDRESS_MASK_REPLY
Table 57
Legal NetBIOS Commands
MESSAGE:
REQUEST:
POSITIVE:
VE:
RETARGET:
KEEPALIVE:
Table 58
Legal SMTP Commands
AUTH
DATA
EHLO
ETRN
EXPN
HELO
HELP
NOOP
QUIT
RCPT
RSET
SAML
SEND
SOML
TURN
VRFY
Содержание 802.11g HomePlug AV ADSL2+ Gateway P-660HWP-Dx
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Страница 7: ...Safety Warnings P 660HWP Dx User s Guide 39 ...
Страница 8: ...Safety Warnings P 660HWP Dx User s Guide 40 ...
Страница 10: ...Contents Overview P 660HWP Dx User s Guide 36 ...
Страница 20: ...Table of Contents P 660HWP Dx User s Guide 44 ...
Страница 32: ...List of Tables P 660HWP Dx User s Guide 40 ...
Страница 33: ...35 PART I Introduction Introducing the P 660HWP Dx 35 Introducing the Web Configurator 43 ...
Страница 34: ...36 ...
Страница 41: ...Chapter 1 Introducing the P 660HWP Dx P 660HWP Dx User s Guide 41 Figure 7 P 660HWP Dx with ISDN ...
Страница 42: ...Chapter 1 Introducing the P 660HWP Dx P 660HWP Dx User s Guide 42 ...
Страница 56: ...Chapter 2 Introducing the Web Configurator P 660HWP Dx User s Guide 48 ...
Страница 57: ...35 PART II Wizards Wizard Setup for Internet Wireless Access 59 Bandwidth Management Wizard 73 ...
Страница 58: ...36 ...
Страница 78: ...Chapter 4 Bandwidth Management Wizard P 660HWP Dx User s Guide 54 ...
Страница 80: ...36 ...
Страница 98: ...Chapter 5 WAN Setup P 660HWP Dx User s Guide 52 ...
Страница 142: ...Chapter 8 Powerline P 660HWP Dx User s Guide 42 ...
Страница 155: ...35 PART IV Security Firewalls 157 Firewall Configuration 169 Content Filtering 191 Certificates 195 ...
Страница 156: ...36 ...
Страница 176: ...Chapter 11 Firewall Configuration P 660HWP Dx User s Guide 54 Figure 99 Firewall Edit Rule ...
Страница 190: ...Chapter 11 Firewall Configuration P 660HWP Dx User s Guide 68 ...
Страница 194: ...Chapter 12 Content Filtering P 660HWP Dx User s Guide 72 ...
Страница 218: ...36 ...
Страница 222: ...Chapter 14 Static Route P 660HWP Dx User s Guide 38 ...
Страница 238: ...Chapter 16 Dynamic DNS Setup P 660HWP Dx User s Guide 38 ...
Страница 250: ...Chapter 17 Remote Management Configuration P 660HWP Dx User s Guide 46 ...
Страница 262: ...Chapter 18 Universal Plug and Play UPnP P 660HWP Dx User s Guide 58 ...
Страница 263: ...35 PART VI Maintenance and Troubleshooting System 265 Logs 271 Tools 289 Diagnostic 295 Troubleshooting 297 ...
Страница 264: ...36 ...
Страница 270: ...Chapter 19 System P 660HWP Dx User s Guide 40 ...
Страница 288: ...Chapter 20 Logs P 660HWP Dx User s Guide 52 ...
Страница 294: ...Chapter 21 Tools P 660HWP Dx User s Guide 40 ...
Страница 304: ...36 ...
Страница 340: ...Appendix C Internal SPTGEN P 660HWP Dx User s Guide 50 ...
Страница 364: ...Appendix E IP Subnetting P 660HWP Dx User s Guide 42 ...
Страница 368: ...Appendix F Command Interpreter P 660HWP Dx User s Guide 38 ...
Страница 388: ...Appendix K Legal Information P 660HWP Dx User s Guide 38 ...
Страница 394: ...Appendix L Customer Support P 660HWP Dx User s Guide 40 ...
Страница 402: ...Index P 660HWP Dx User s Guide 42 ...