Commands

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Module 6: Layer 4 Troubleshooting

6.2.2

Gathering information on ACL operation

> Router#show logging [history | slot slot-number | summary]
> Router#show ip access-list [access-list-number | access-list-name]
> Router#clear access-list counters {access-list-number | access-list-name}

6.2.5

Gathering information on NAT configuration and operation

> Router#show ip nat statistics
> Router#show ip nat translations [verbose]
> Router#debug ip nat [access-list | detailed | h323 | pptp]
> Router#clear ip nat translation {* | [inside global-ip local-ip] [outside local-ip global-ip]}

6.2.6

Other useful information

> Router(config)#logging on
> Router(config)#logging buffered [buffer-size | level]
> Router#clock set hh:mm:ss day month year
> Router#clock set hh:mm:ss month day year
> Router(config)#ntp peer ip-address [version number] [key keyid] [source interface] [prefer]
> Router(config)#clock timezone zone hours-offset [minutes-offset]
> Router(config)#service timestamps message-type [uptime]
> Router(config)#service timestamps message-type datetime [msec] [localtime] [show-timezone]

6.3.3

Gathering transport layer information on UNIX machines

> man [tool_name]
> ipfwadm (UNIX kernel version 2.0)
> ipchains (UNIX kernel version 2.2)
> iptables (UNIX kernel version 2.4)
> ifconfig
> netstat
> route
> ip
> netcat

6.3.4

Common issues with NetBIOS networks

> netbios-name-server name-server-address
> netbios-node-type type

6.3.5

Gathering NetBIOS information

> netstat
> nbstat

6.4.3

Solving the component problems

> Router(config-ext-nacl)#deny protocol source source-wildcard destination destination-wildcard [precedence precedence] [tos tos] [log] [time-range time-range-name]

6.4.4

Dynamic NAT and extended ACLs

> Router(config)#ip nat translation timeout seconds
> Router(config)#ip nat translation udp-timeout seconds
> Router(config)#ip nat translation dns-timeout seconds
> Router(config)#ip nat translation tcp-timeout seconds
> Router(config)#ip nat translation finret-timeout seconds

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