Cisco Ethernet switch Instrukcja Użytkownika Pobierz pdf (Strona 52)

525252

© 2002, Cisco Systems, Inc. All rights reserved.

l2-security-bh.ppt

Spanning Tree Attacks and Methods

¥ Standard 802.1d STP takes 30-45

seconds to deal with a failure or

Root bridge change (nice DoS)

Generally only devices affected by the

failure notice the issue

PortFast and UplinkFast can greatly

improve this

¥ Sending BPDUs from the attacker

can force these changes and create

a DoS condition on the network

¥ As a link with macof: the TCN

message will result in the CAM table

aging all entries in 15 seconds if

they do not communicate (the

default is 300 seconds)

¥ Testing using brconfig on OpenBSD

was easily able to create the DoS

condition. Depending on the

topology it could also yield more

packets available for the attacker

1 2 ... 47 48 49 50 51 52 53 54 55 56 57 ... 83 84

Komentarze do niniejszej Instrukcji

Brak uwag