TROUBLESHOOTING THE NETWORK
input into the monitoring software so that they are indeed being watched.
INITIAL INSTALLATION ISSUES & ANSWERS Pick the Right Addresses: Most of the problems that develop during the initial installation of IP- enabled security devices center on the proper selection of static IP addresses for the new com- ponents, cabling deficiencies, and the use of soft- ware ports to allow remote access to a device from another network or over the Internet. Installers must investigate the current IP address-
es in use by the LAN to which the device(s) are to be connected. A simple way to do this is to perform the “ipconfig” command from any PC that is cur- rently connected to the target LAN:
SCREEN SHOT COURTESY OF THE AUTHOR
Cabling Testing: All cabling should be considered suspect until tested, whether the cabling was installed new by the security company or is existing cabling being repurposed for IP security communications. This testing process is often overlooked, even though over 50 percent of network connectivity problems stem from bad/poor cabling and connectors. Always test every UTP cable with a two-ended tester and replace any suspect connectors. A particular problem with RJ-45 male sockets is the spring clip that holds the connector into the female socket; these clips often lose their “spring” over time and don’t provide a solid lock-in when inserted into a device or switch. If it doesn’t click in securely, replace it now and avoid a spurious service call later when the weak connector clip causes the connection to fail.
Fiber optic links can be tested for continuity with
Performing the “ipconfig” command on one of your client’s LAN-connected PCs will provide the network address range, subnet mask and default gateway in use.
This report will show what IP address range is in use, what is the proper subnet mask setting, and the address of the default gateway or router. Using this information, security technicians then can select an unused address in the same range as those on the net- work, and input the same subnet mask and default gateway. Smart technicians will test the static IP address they’ve selected for the new component(s) by firing off a “Ping” test against the proposed IP address. If no responses occur, then there is nothing on the LAN currently using the selected IP address. This step is very important, because a duplicated IP address on a LAN will create communications fail- ures for both the existing device and the new device that duplicates the address.
SCREEN SHOT COURTESY OF THE AUTHOR
any flashlight. Just hold one connector end onto the turned-on flashlight and have someone else look at the other end. If the light comes through, the fiber and its connectors aren’t broken. If the light doesn’t go through, this particular fiber link is broken, with most breakage occurring at either of the connector ends or at any splices, if they exist. Be prepared to replace fiber connectors with the appropriate type when planning to use existing fiber links, as there have been many examples of mediocre to bad fiber connectors being installed onto unused or dark fibers. Software Port Programming: In most cases the maximum benefit of installing IP-enabled security devices is the ability to access the devices, such as an NVR, from remote locations over the Internet. To provide this accessibility, technicians need to understand and properly program the software port(s) into the proper locations in the network. The first setting is typically in the NVR or IP-enabled devices, most of which are default programmed to software port 80. This is also called the hypertext transfer protocol port or HTTP. Smart network security planning requires that this port number be changed, preferably to a number higher than 1600. Because there are 65,435 soft- ware ports, selecting a higher port number for a security device makes it harder for outside hackers to use scanning software to find an open port in a LAN from over the Internet, as they would need to scan thousands of ports to find the open ones. Once the port(s) has been selected in the LAN
This “ping” test shows that the address 192.168.1.77 is not is use by any other device on the LAN at the time the test was performed.
66 November 2010
device, the exact same port number(s) must be programmed into the default gateway router in the network address translation (NAT) field, and any firewalls that reside between the LAN and the
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174