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Standard ACL 37 — block host .11 from the Library server
Security Intermediate 5 devices 4 checked tasks 100 points Plan lab
Host 10.56.1.11 must not reach the Library server at 10.56.2.10, but the rest of its LAN must. Write a standard ACL (number 46), put it close to the destination — outbound on the server-facing interface — and prove both outcomes. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
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The scenario
Host 10.56.1.11 must not reach the Library server at 10.56.2.10, but the rest of its LAN must. Write a standard ACL (number 46), put it close to the destination — outbound on the server-facing interface — and prove both outcomes.
Your role: a security engineer. Level: Intermediate Done when: all 4 goals show as passed (100 points).
Network status
Devices: 1 router, 1 switch, 3 PCs, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. R-Trichy starts with addresses (G0/0 10.56.1.1/24, G0/1 10.56.2.1/24). Host-11 is a host with 10.56.1.11/24, gateway 10.56.1.1. Host-12 is a host with 10.56.1.12/24, gateway 10.56.1.1. Library-Server is a host with 10.56.2.10/24, gateway 10.56.2.1. SW-Trichy starts with an empty configuration. Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
ACL 46 denies host 10.56.1.11 and permits everyone else (30 pts) It is applied outbound on Gi0/1 (the server side) (20 pts) Host .11 can no longer reach the server (25 pts) Host .12 still can (25 pts) The activity, in order
ACL 46 denies host 10.56.1.11 and permits everyone else Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config It is applied outbound on Gi0/1 (the server side) Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config Host .11 can no longer reach the server Why: Blocking traffic is half of security. You prove a block by showing the same ping that worked before now fails. Verify with: ping 10.56.2.10 Host .12 still can Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 10.56.2.10 Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: Placing a standard ACL near the source, blocking too much Common mistake: Forgetting the final permit any (implicit deny) Common mistake: Applying in instead of out Why this matters
A standard ACL looks only at the source address, so it belongs as close to the destination as possible — otherwise it blocks the source from everything. Every ACL ends in an invisible deny, so a permit any is needed.
What you will be able to do
Write a numbered standard ACL
Apply it in the right direction on the right interface
Test a deny and a permit
The network
ISR 2911, Catalyst 2960-24TT, PC — 5 devices in all, already cabled.
Gi0/1 Gi0/0 10.56.1.1/24 Fa0/1 Fa0 Fa0/2 Fa0 Fa0 Gi0/1 10.56.2.1/24 R-Trichy SW-Trichy Host-11 10.56.1.11/24 · gw 10.56.1.1 Host-12 10.56.1.12/24 · gw 10.56.1.1 Library-Server 10.56.2.10/24 · gw 10.56.2.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
R-Trichy ISR 2911 configure it SW-Trichy Catalyst 2960-24TT configure it Host-11 PC 10.56.1.11 / 255.255.255.0 gw 10.56.1.1 Host-12 PC 10.56.1.12 / 255.255.255.0 gw 10.56.1.1 Library-Server PC 10.56.2.10 / 255.255.255.0 gw 10.56.2.1
Cabling
SW-Trichy Gi0/1 ↔ R-Trichy Gi0/0 SW-Trichy Fa0/1 ↔ Host-11 Fa0 SW-Trichy Fa0/2 ↔ Host-12 Fa0 Library-Server Fa0 ↔ R-Trichy Gi0/1
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
R-Trichy interface g0/0
ip address 10.56.1.1 255.255.255.0
no shutdown
exit
interface g0/1
ip address 10.56.2.1 255.255.255.0
no shutdown
exit Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 ACL 46 denies host 10.56.1.11 and permits everyone else 30 On R-Trichy: show running-config contains the line(s) matching access-list 46 deny\s+(host )?10\.56\.1\.11[\s\S]*access-list 46 permit any. 2 It is applied outbound on Gi0/1 (the server side) 20 On R-Trichy: show running-config contains the line(s) matching interface GigabitEthernet0/1 … ip access-group 46 out. 3 Host .11 can no longer reach the server 25 On Host-11: ping 10.56.2.10 must fail — the policy blocks it. 4 Host .12 still can 25 On Host-12: ping 10.56.2.10 must succeed.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
Placing a standard ACL near the source, blocking too much
Forgetting the final permit any (implicit deny)
Applying in instead of out
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
R-Trichy access-list 46 deny host 10.56.1.11
access-list 46 permit any
interface g0/1
ip access-group 46 out
exit Where this is examined
CCNA 5.6 Access Control Lists; Security+ 3.2.
This lab practises these topics in the zNetLaB certification courses:
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