Manuale d’uso / di manutenzione del prodotto 10~100 Series del fabbricante ZyXEL Communications
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ZyW ALL 10~100 Series Internet Security Gateway Reference Guide Versions 3.52, 3.60 and 3.61 March 2003.
ZyWALL 10~100 Series Internet Security Gateway ii Copyright Copyright Copyright © 2003 by Zy XEL Communications Corporation. The contents of this publi cation may not be reproduced i n any part or a .
ZyWALL 10~100 Series Internet Security Gateway FCC iii Federal Communications Commission (FCC) Interference S tatement This device complies with Part 15 of FCC rules. Operation is subject to the following two cond itions: This device m ay not cause harm ful interference.
ZyWALL 10~100 Series Internet Security Gateway iv Information for Canadian Users Information for Canadian Users The Industry Canada label identifies certified equipmen t. This certification means that the equipment meets certain telecommunications network pr otective, op eration, and safety requ irements.
ZyWALL 10~100 Series Internet Security Gateway Warranty v ZyXEL Limited W arranty ZyXEL warrants to the original end us er (purchaser) that this product is free from any defects in materials or workmanshi p for a peri od of up t o two years from the date of purchase .
ZyWALL 10~100 Series Internet Security Gateway vi Customer Support Customer Support When you contact your cu stomer support r epresenta tive please have t he followi ng inform ation ready: Please have th e following i nformation re a dy when you cont act customer support.
ZyWALL 10~100 Series Internet Security Gateway Table of Contents vii T able of Content s Copyright...................................................................................................................... ................................ii Federal Communications Commission (FCC) Interfer en ce S tatemen t.
ZyWALL 10~100 Series Internet Security Gateway viii Table of Contents Index ...........................................................................
ZyWALL 10~100 Series Internet Security Gateway List of Diagrams ix List of Diagrams Diagram 2-1 Id eal Se tup ........................................................................................................ ........................ 2-1 Diagram 2-2 “T riangl e Route” Pr oblem .
ZyWALL 10~100 Series Internet Security Gateway x List of Charts List of Chart s Chart 8-1 Classes of IP Addresses .............................................................................................. .................... 8-1 Chart 8-2 Allowed IP Ad dress Range By Class .
ZyWALL 10~100 Series Internet Security Gateway List of Charts xi Chart 13-1 1 Sample IPSec Logs Du ring Packet T ransmission .................................................................. 13-15 Chart 13-12 RFC-2408 IS AKMP Payload T ypes .........
ZyWALL 10~100 Series Internet Security Gateway xii Preface Preface About Y our ZyW A LL Congratulations on your pur chase of the ZyWALL Security Gateway. About This User's Manual This manual i s designed to provide background inf ormation on some of the Zy WALL’s features.
ZyWALL 10~100 Series Internet Security Gateway Preface xiii Synt ax Conventions • “Enter” means for you t o type one or more charact ers and press the carriage return. “Select” or “Choose” means for you t o use one of the predefined c hoices.
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General Information I Part I: General Information This part prov ides background information abo ut setting up your computer ’s IP address, triangle route, how functions are related, wireless LAN, 802.
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ZyWALL 10~100 Series Internet Security Gateway Setting Up Y our Computer ’s IP Address 1-1 Chapter 1 Setting up Your Computer’s IP Address All computers must have a 1 0M or 100M Et he rnet adapter card and TCP/IP installed.
ZyWALL 10~100 Series Internet Security Gateway Setting Up Your Computer’s IP Address 1-2 The Network window Configuration ta b displays a list of i nstalled com ponents. You need a network adapter, the T CP/IP prot ocol and C lient for Microsoft Networks.
ZyWALL 10~100 Series Internet Security Gateway Setting Up Y our Computer ’s IP Address 1-3 1. Click the IP Address tab. -If your IP address is dynamic, select Obtain an IP address automatically . -If you have a static IP address, select Specify an IP address and type your informatio n into the IP Address and Subne t Mask fields.
ZyWALL 10~100 Series Internet Security Gateway Setting Up Your Computer’s IP Address 1-4 3. Click the Gateway tab. -If you do not know your gateway’s IP address, remove previously installed gate ways. -If you have a gateway IP address, type it in the Ne w ga te way fie ld and click Add .
ZyWALL 10~100 Series Internet Security Gateway Setting Up Y our Computer ’s IP Address 1-5 1. For Windows XP, click start , Control Panel . In Windows 2000/NT, click Start , Settings , Control Panel . 2. For Windows XP, click Network Connections . For Windows 2000/NT, click Network and Dial-up Connections .
ZyWALL 10~100 Series Internet Security Gateway Setting Up Your Computer’s IP Address 1-6 4. Select Internet Protocol (TCP/IP) (under the General tab in Win XP) and click Properties . 5. The Internet Protocol TCP/IP Properties window opens (the General tab in Windows XP).
ZyWALL 10~100 Series Internet Security Gateway Setting Up Y our Computer ’s IP Address 1-7 6. -If you do not know your gateway's IP address, remove any previously installed gate ways in the IP Settin gs tab and click OK .
ZyWALL 10~100 Series Internet Security Gateway Setting Up Your Computer’s IP Address 1-8 7. In the Internet Protocol TCP/IP Properties window (the Gene ral t ab in Windows XP): -Click Obtain DNS server address automatically if you do not know your DNS server IP address(es).
ZyWALL 10~100 Series Internet Security Gateway Setting Up Y our Computer ’s IP Address 1-9 1. Click the Apple menu, Control Panel and double-click TCP/IP to open the TCP/IP Control Panel . 2. Select Ethernet built-in from the Connect v ia list. 3. For dynamically assigned settings, sel ect Using DHCP Server from the Configure: list.
ZyWALL 10~100 Series Internet Security Gateway Setting Up Your Computer’s IP Address 1-10 4. For statically assigned settings, do the follo wing: -From the Configure box, select Manually . -Type your IP address in the IP Address box. -Type your subnet mask in the Subnet mask box.
ZyWALL 10~100 Series Internet Security Gateway Setting Up Y our Computer ’s IP Address 1-1 1 2. Click Network in the icon bar. - Select Automatic from the Location list. - Select Built-in Ethernet from the Show list. - Click the TCP/IP tab. 3. For dynamically assigned settings, sel ect Using DHCP from the Configure list.
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ZyWALL 10~100 Series Internet Security Gateway T riangle Route 2-1 Chapter 2 Triangle Route The Ideal Setup When the firewall is on, your ZyWALL acts as a secure gateway between your LAN and the Intern et. In an ideal network top ology, all i ncoming and outgoing net work traffic pas ses through t he ZyWALL to protect your LAN against attacks.
ZyWALL 10~100 Series Internet Security Gateway Triangle Route 2-2 Diagram 2-2 “Triangle Route” Problem The “T riangle Route” Solutions This section presents you two solutions to the “triangle route” problem. IP Aliasing IP alias allows you to partition your network into logi cal sections over the same Ethernet interface.
ZyWALL 10~100 Series Internet Security Gateway T riangle Route 2-3 Gateways on the W AN Side A second sol ution to the “triangle r oute” proble m is to put all of your network g ateways on t he WAN si de as the following fig ure shows. This en sures that all incoming netwo rk traffic p asses through your ZyWALL to your LAN.
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ZyWALL 10~100 Series Internet Security Gateway The Big Picture 3-1 Chapter 3 The Big Picture The following figure giv es an overview of ho w filtering, the firewall, VPN and NAT are related.
ZyWALL 10~100 Series Internet Security Gateway The Big Picture 3-2.
ZyWALL 10~100 Series Internet Security Gateway Wireless LAN and IEEE 802.1 1 4-1 Chapter 4 Wireless LAN and IEEE 802.11 A wireless LAN (WLA N) provides a flexi ble data commun ications system that y ou can use to access various services (navigating the Internet, em ail, prin ter services, etc.
ZyWALL 10~100 Series Internet Security Gateway The Big Picture 4-2 The IEEE 802.11 specifies three di ffere nt transmission me thods for th e PHY, the layer responsible for transferring dat a between nodes.
ZyWALL 10~100 Series Internet Security Gateway Wireless LAN and IEEE 802.1 1 4-3 Diagram 4-1 Peer-to-Peer Communication in an Ad -hoc Network Infrastructure Wireless LAN Configuration For Infrastructure WLANs, m ultiple Access Points (APs) link the WLAN to the wired network and al low users to efficiently share network resources.
ZyWALL 10~100 Series Internet Security Gateway The Big Picture 4-4 could be any type of net work, it is almost invari ably an Ethernet LAN. Mo bile nodes ca n roam betwee n Access Points and seam less campus-wide coverage is possible.
ZyWALL 10~100 Series Internet Security Gateway Wireless LAN with IEEE 802.1x 5-1 Chapter 5 Wireless LAN With IEEE 802.1x As wireless networks becom e popular for both portable com puting and c o rporate networ ks, security i s now a priority. Security Flaws wi th IEEE 802.
ZyWALL 10~100 Series Internet Security Gateway Wireless LAN with IEEE 802.1x 5-2 • Support for RADIUS (Rem o te Au thentication Dial In User Service, RFC 2138, 2139) for centralized use r profile a nd accountin g managem ent on a ne twork RADI US server.
ZyWALL 10~100 Series Internet Security Gateway PPPoE 6-1 Chapter 6 PPPoE PPPoE in Action An ADSL m odem bridges a PPP session over Ethernet (PPP ove r Ethernet, R FC 2516) f rom your PC to an ATM PVC (Pe rmanent Virt ual Circuit ), which connect s to a DSL Ac cess Concentrat or where the PPP session terminates (see the next figure).
ZyWALL 10~100 Series Internet Security Gateway 6-2 PPPoE How PPPoE W orks The PPPoE driver m akes the Ethernet appear as a serial link to the PC and the PC runs PPP over it, while the modem bridges the Et hernet frames to the Access Concen trator (AC).
ZyWALL 10~100 Series Internet Security Gateway PPTP 7-1 Chapter 7 PPTP What is PPTP? PPTP (Point -to-Point T unneling Prot ocol) is a Microsoft proprietary protocol (R FC 2637 f or PPTP is informational only) to tunnel PPP frames.
ZyWALL 10~100 Series Internet Security Gateway 7-2 PPTP PPTP Protocol Overview PPTP is very si milar to L2TP, since L2T P is based on both PPTP a nd L2F (C isco’s Layer 2 Forwardin g). Conceptually, there are three parties in PPTP, name ly the PNS (PPTP Network Serve r), the PAC (PPTP Access Concentrator) and the PPTP user.
ZyWALL 10~100 Series Internet Security Gateway PPTP 7-3 Diagram 7-3 Example Message Exchange bet w een PC and an ANT PPP Data Connection The PPP frames are tunneled betwee n the PNS and PAC over GRE (General Ro uting Encapsulation, RFC 1701, 1702). The indiv idual calls within a tunnel are distingu ished using the Call ID field in the GRE header.
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ZyWALL 10~100 Series Internet Security Gateway IP Subnetting 8-1 Chapter 8 IP Subnetting IP Addressing Routers “route” base d on the network num ber.
ZyWALL 10~100 Series Internet Security Gateway 8-2 IP Subnetting A class “B” address (1 6 host bit s) can have 2 16 –2 or 65534 hosts. A class “A” address (24 host bits) can have 2 24 –2 hosts (app roxima tely 16 m illion hosts ).
ZyWALL 10~100 Series Internet Security Gateway IP Subnetting 8-3 With subnetting, the class arrangement of an IP address is ignored. For example, a class C address no longer has to have 24 bits of network number and 8 bits of ho st ID. With subnetting, some of the ho st ID bits are converted into netwo rk number bits.
ZyWALL 10~100 Series Internet Security Gateway 8-4 IP Subnetting The first three octets of the a ddress make up the networ k number (cl ass “C”). You wa nt to have two separat e networks. Divide the network 19 2.168.1.0 i nto two se parate subnet s by con verting one o f the host ID bits of the IP address to a networ k number bit.
ZyWALL 10~100 Series Internet Security Gateway IP Subnetting 8-5 192.168.1.0 with mask 255.255.255 .128 is the subnet its elf, and 192.168.1.1 27 with mask 255.255.255.12 8 is the directed broadcast addre ss for the first subnet. Theref ore, the lowest IP address t hat can be assigned to an actual host for the first subn et is 192.
ZyWALL 10~100 Series Internet Security Gateway 8-6 IP Subnetting Subnet Address: 192. 168.1.128 Lo west Ho st ID: 192.168.1.129 Broadcast Address: 192.168. 1.191 Hig hest Host ID: 192.168.1.190 Chart 8-10 Subnet 4 NETWORK NUMBER LAST OCTET BIT VA L UE IP Address 192.
ZyWALL 10~100 Series Internet Security Gateway IP Subnetting 8-7 Chart 8-12 Class C Subnet Planning NO. “BORROWED” HOST BITS SUBNET MASK NO. SUBNETS NO. HOSTS PER SUBNET 1 255.255.255.128 (/25) 2 126 2 255.255.255.192 (/26) 4 62 3 255.255.255.224 (/27) 8 30 4 255.
ZyWALL 10~100 Series Internet Security Gateway 8-8 IP Subnetting Chart 8-13 Class B Subnet Planning NO. “BORROWED” HOST BITS SUBNET MASK NO. SUBNETS NO. HOSTS PER SUBNET 9 255.255.255.128 (/25) 512 126 10 255.255.255.192 (/26) 1024 62 11 255.255.255.
Command and Log Information II Part II: Command and Log Information This part prov ides information on the command interp reter interface, firewall and NetBIOS commands and logs and password prot ection.
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ZyWALL 10~100 Series Internet Security Gateway Command Interpreter 9-1 Chapter 9 Command Interpreter The following describes how to use the command interpreter. Enter 24 in the main menu to bring up the system m a intenance m enu. Enter 8 to go t o Menu 24.
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ZyWALL 10~100 Series Internet Security Gateway Firewall Commands 10-1 Chapter 10 Firewall Commands The following descri bes the firewall comm ands. See the Command Interpreter appendix fo r information on the command structure.
ZyWALL 10~100 Series Internet Security Gateway 10-2 Firewall Commands Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION config display firewall attack This command sho ws all of the attack response settings. config display firewall e-mail This command sho ws all of the e-mail settings.
ZyWALL 10~100 Series Internet Security Gateway Firewall Commands 10-3 Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION config edit firewall e-mail hour <0-23> This command sets the hour when the firewall log is sent through e- mail if the ZyWALL is set to send it on an hourly, daily or weekly basis.
ZyWALL 10~100 Series Internet Security Gateway 10-4 Firewall Commands Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION config edit firewall attack minute-low <0-255> This command sets the threshold of half-op en sessions where the ZyWALL stops del eting half-opened sessions.
ZyWALL 10~100 Series Internet Security Gateway Firewall Commands 10-5 Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION Config edit firewall set <set #> connection-timeout <seconds> This command sets how long Z yWALL waits for a TCP session to be established befor e dropping the session.
ZyWALL 10~100 Series Internet Security Gateway 10-6 Firewall Commands Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION Config edit firewall set <set #> rule <rule #> alert <yes | no> This command sets whether or not the ZyWALL sends an alert e-mail when a DOS attack or a violation of a particular rule occurs.
ZyWALL 10~100 Series Internet Security Gateway Firewall Commands 10-7 Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION config edit firewall set <set #> rule <rule #> TCP destport- single <port #> This command sets a rule to have the ZyWALL check for TCP traffic with this destination address.
ZyWALL 10~100 Series Internet Security Gateway 10-8 Firewall Commands Chart 10-1 Fire w all Commands FUNCTION COMMAND DESCRIPTION config delete firewall set <set #> rule <rule #> This command removes the specified rul e in a firewall configuration set.
ZyWALL 10~100 Series Internet Security Gateway NetBIOS Filter Commands 11-1 Chapter 11 NetBIOS Filter Commands The following describes the NetBIOS packet filter commands.
ZyWALL 10~100 Series Internet Security Gateway 11-2 NetBIOS Filter Commands This command gives a read-only list of the current NetBIOS filter modes for a ZyWALL that does not have DMZ.
ZyWALL 10~100 Series Internet Security Gateway NetBIOS Filter Commands 11-3 Chart 11-1 NetBIOS Filter Default Settings NAME DESCRIPTION EXAMPLE WAN to DMZ This field displays whether NetBIOS packets are blocked o r forwarded from the WAN to the DMZ.
ZyWALL 10~100 Series Internet Security Gateway 11-4 NetBIOS Filter Commands <on|off> = For types 0 and 1 , use on to enable the filter and block NetBIOS packets. Use off to disable the filter and forward NetBIOS packets. For type 6 , use on to bloc k NetBIOS packets from being sent t hrough a V PN connection.
ZyWALL 10~100 Series Internet Security Gateway Boot Commands 12-1 Chapter 12 Boot Commands The BootMod ule AT comm an ds execute from within the router’s bootu p software, whe n debug mode i s selected before the m ain router firm ware (ZyNOS) is started.
ZyWALL 10~100 Series Internet Security Gateway 12-2 Boot Commands Diagram 12-2 Boot Module Comm ands AT just answer OK ATHE print help ATBAx change baudrate.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-1 Chapter 13 Log Descriptions Chart 13-1 System Error Logs LOG MESSAGE DESCRIPTION %s exceeds the max. number of session per host! This attempt to create a NAT session exceeds the maximum number of NAT session table entries allowed to be crea ted per host.
ZyWALL 10~100 Series Internet Security Gateway 13-2 Log Descriptions Chart 13-2 System Maintenanc e Logs TELNET Login Fail Someone has failed to log on to the router via telnet. FTP Login Successfully Someone has logged on to the router via ftp. FTP Login Fail Someone has failed to log on to the router via ftp.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-3 Chart 13-5 Attack Log s LOG MESSAGE DESCRIPTION attack IGMP The firewall detected an IGMP attack. attack ESP The firewall detected an ESP attack. attack GRE The firewall detected a GRE attack.
ZyWALL 10~100 Series Internet Security Gateway 13-4 Log Descriptions Chart 13-5 Attack Log s LOG MESSAGE DESCRIPTION syn flood TCP The firewall detected a TCP syn flood attack. ports scan TCP The firewall detected a TCP port scan attack. teardrop TCP The firewall detected a TCP teardrop attack.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-5 Chart 13-6 Access Logs LOG MESSAGE DESCRIPTION Firewall default policy: TCP (set:%d) TCP access matched the default po licy of the listed ACL set and the ZyWALL blocked or for warded it according to the ACL set’s configuration.
ZyWALL 10~100 Series Internet Security Gateway 13-6 Log Descriptions Chart 13-6 Access Logs LOG MESSAGE DESCRIPTION Firewall rule match: IGMP (set:%d, rule:%d) IGMP access matched the listed firewall rule and the ZyWALL blocked or forwarded it according to the rule’s configuration.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-7 Chart 13-6 Access Logs LOG MESSAGE DESCRIPTION Firewall rule NOT match: OSPF (set:%d, rule:%d) OSPF access did not match the listed firewall rule and the Z yWALL logged it.
ZyWALL 10~100 Series Internet Security Gateway 13-8 Log Descriptions Chart 13-6 Access Logs LOG MESSAGE DESCRIPTION Filter match DROP <set %d/rule %d> ICMP access matched the listed filter rule and the Z yWALL dropped the packet to block access.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-9 Chart 13-6 Access Logs LOG MESSAGE DESCRIPTION Firewall sent TCP reset packets The firewall sent out TCP reset packets. Packet without a NAT table entry blocked The router blocked a packet that did not h ave a corresponding NAT table entry.
ZyWALL 10~100 Series Internet Security Gateway 13-10 Log Descriptions Chart 13-7 ACL Setting Notes ACL SET NUMBER DIRECTION DESCRIPTION 9 DMZ to DMZ/ZyWALL ACL set 9 for packets traveling from the DMZ to the DM or the ZyWALL.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-11 Chart 13-8 ICMP Notes TYPE CODE DESCRIPTION 0 Echo message 11 Time Exceeded 0 Time to live exceeded in transit 1 Fragment reassemb.
ZyWALL 10~100 Series Internet Security Gateway 13-12 Log Descriptions Diagram 13-1 Example VPN Initiator IPSec Log VPN Responder IPSec Log The following f igure shows a typ ical log from the VPN connect ion pee r. Diagram 13-2 Example VPN Responder IPSec Log This menu is useful f or troubleshoot ing.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-13 The following table sh ows sample log messages during IKE key exchange. Chart 13-10 Sample IKE Key Exchange Logs LOG MESSAGE DESCRIPTION Send <Symbol> Mode request to <IP> Send <Symbol> Mode request to <IP> The ZyWALL has started negotiation with the peer.
ZyWALL 10~100 Series Internet Security Gateway 13-14 Log Descriptions Chart 13-10 Sample IKE Key Exchange Logs LOG MESSAGE DESCRIPTION !! Remote IP <IP start> / <IP end> conflicts If the security gateway is “0.0.0.0”, the ZyWALL will use the peer’s “Local Addr” as its “Remote Addr”.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-15 Chart 13-10 Sample IKE Key Exchange Logs LOG MESSAGE DESCRIPTION vs. My Local <IP address> The IP address type or IP address of an incoming packet does not match the peer IP address type or IP address configured on the loc al router.
ZyWALL 10~100 Series Internet Security Gateway 13-16 Log Descriptions The following table shows RFC-2408 I SAKMP payload types that the log displays. Please r efer to the RFC for detailed information on each type.
ZyWALL 10~100 Series Internet Security Gateway Log Descriptions 13-17 Log Commands Go to the command interpreter interface (the Comman d Interpret er Appendix explains how to access a nd use the commands).
ZyWALL 10~100 Series Internet Security Gateway 13-2 Log Descriptions Use the sys logs display [log category] comm and to show the logs in an individual ZyWALL log category.
ZyWALL 10~100 Series Internet Security Gateway Brute-Force Password Gu essing Protection 14-1 Chapter 14 Brute-Force Password Guessing Protection The followin g describes t he commands for enabling, disabli ng and con figuring the brute-force password guessing pr otection m echanism for the password .
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Index III Part III: Index This part prov ides an Index of key terms..
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ZyWALL 10~100 Series Internet Security Gateway Index A Index A Ad-hoc Configuration ...................................... 4-2 Alternative Subnet Mask Notation ................... 8-3 B Basic Service Set.............................................. 4-2 Big Picture .
ZyWALL 10~100 Series Internet Security Gateway B Index Infrastructure Configuration ............................ 4-3 IP Addressing .................................................. 8-1 IP Classes ......................................................
Un punto importante, dopo l’acquisto del dispositivo (o anche prima di acquisto) è quello di leggere il manuale. Dobbiamo farlo per diversi motivi semplici:
Se non hai ancora comprato il ZyXEL Communications 10~100 Series è un buon momento per familiarizzare con i dati di base del prodotto. Prime consultare le pagine iniziali del manuale d’uso, che si trova al di sopra. Dovresti trovare lì i dati tecnici più importanti del ZyXEL Communications 10~100 Series - in questo modo è possibile verificare se l’apparecchio soddisfa le tue esigenze. Esplorando le pagine segenti del manuali d’uso ZyXEL Communications 10~100 Series imparerai tutte le caratteristiche del prodotto e le informazioni sul suo funzionamento. Le informazioni sul ZyXEL Communications 10~100 Series ti aiuteranno sicuramente a prendere una decisione relativa all’acquisto.
In una situazione in cui hai già il ZyXEL Communications 10~100 Series, ma non hai ancora letto il manuale d’uso, dovresti farlo per le ragioni sopra descritte. Saprai quindi se hai correttamente usato le funzioni disponibili, e se hai commesso errori che possono ridurre la durata di vita del ZyXEL Communications 10~100 Series.
Tuttavia, uno dei ruoli più importanti per l’utente svolti dal manuale d’uso è quello di aiutare a risolvere i problemi con il ZyXEL Communications 10~100 Series. Quasi sempre, ci troverai Troubleshooting, cioè i guasti più frequenti e malfunzionamenti del dispositivo ZyXEL Communications 10~100 Series insieme con le istruzioni su come risolverli. Anche se non si riesci a risolvere il problema, il manuale d’uso ti mostrerà il percorso di ulteriori procedimenti – il contatto con il centro servizio clienti o il servizio più vicino.
