Network Engineering

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Discussion on Access-Control-Lists (ACL) or Access-Control-Entries (ACE)

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Allow one way SSH on extended IP access list on Cisco switch

interface GigabitEthernet1/0/11 ip access-group VM01-BLOCK-SSH-ACCESS-OUT out objective: 10.10.10.104 -x-> any 10.10.10.0/24 via SSH any 10.10.10.0/24 via SSH ---> 10.10.10.104 Question: ...
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39 views

Cisco L2 switch port ACL options

I'm trying to understand Cisco Switch ACL options I can potentially use to limit traffic. Switch is a IE2000 series with Lanbase IOS. It is L2, with trunk port to uplink switches, multiple VLANs on ...
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93 views

Access list command for specific IP range in Cisco Router 1921

For example: router(config)#ip access-list extended 101 router(config-ext-nacl)#10 per icmp any host 192.168.1.10 From second command line, how to write a command permit icmp any host range 192.168.1....
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51 views

VLAN Filtering not working

On Cisco devices I'm looking to enable some filtering for one specific vlan (id 110). Here is my config : (192.33.57.177 is the DHCP server host) ip access-list extended VLAN110-DHCP permit ip any ...
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1answer
18 views

Blocking 2 VLANs from accessing a specific VLAN on a network

I'm working on a project in packet tracer and I have a server connected to VLAN 10. VLAN 10 has a single server device on it and the IP scope is a /30. I have 8 other VLANs across 2 sites. The 2 ...
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2answers
35 views

meaning of acl configurations?

how do we know what ACL configuration mean? an example access-list 89 permit tcp host 192.168.10.2 any eq www? does this allow the traffic from the host 192.168.10.2 inside? i'm a bit confused. any ...
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33 views

When do ACLs on SVIs get applied on Cisco Catalyst devices?

I don't understand exactly when an ACL will get applied when on an SVI. Given the following (pseudo) configuration int vlan 100 ip address 10.0.0.1 255.255.255.0 ip access-list in in ip access-...
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45 views

Juniper MX Routing Engine Firewall Filter

I'm having difficulties with something I initially thought would be rather simple. I need to apply an outbound firewall filter on an MX10003's management interface. I'm currently using Lo0.0 as the ...
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3answers
97 views

Egress filtering by blocking unused ports

Our company wants to block data exfiltration. They want to control outbound traffic going out from unused ports. I did traffic flow analysis at our edge firewalls to know which ports are used by our ...
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2answers
361 views

Permit ping and traceroute and deny all other services using an ACL

my topology is shown below: I would like the networks that are connected to Hermes-Router to be accessible from all the other stations only when I use ping and traceroute. I tried to do this using an ...
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32 views

How to configure an ACL on ASA when the inside source IP address is translated by NAT? [closed]

I don't know how to configure an ACL when inside source nat is enabled. In my example, I want to realize bidirectional communication with TCP port 30000 between 172.16.100.100(inside) and 10.10.10.10(...
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1answer
326 views

DNS expire-entry-timer has negative affect on ASA using FQDN ACL

I have a Cisco ASA using FQDN egress ACLs for a host that changes IP addresses every 10 mins (Apple APNS IP address pool). As soon as the TTL expires for the addresses, my internal server requests a ...
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1answer
416 views

Cisco Nexus 9300 TCAM carving

I have Cisco Nexus C9396PX L3 switch and i have configured bunch of ACL (inbound) on it to deny/permit traffic. now if i am trying to add more ACL then getting error that your TCAM table is full. here ...
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2answers
235 views

Restricting TFTP access from Host to Router using extended ACL in Cisco IOS

I am trying the below Extended ACLs to restrict TFTP but still I am able to upload files to the router using tftp. Not sure, what is wrong, can you all help? Approach 1: permit udp host <ip> ...
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4answers
149 views

ACL on routers to block TCP/UDP ports

How routers understand the layer 4 port numbers to be blocked in ACL? When an ACL to block TCP/UDP traffic with certain port numbers is applied on a router/L3 interface , how will router understand ...
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1answer
66 views

N2K-C2248TP-1GE question

We are working with Cisco 2960 and Cisco 4948 switches as our top of rack switches and we want to purchase some N2K-C2248TP-1GE , and connect N2K-C2248TP-1GE to our edge switches, (our edge switches ...
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1answer
238 views

delete object network in cisco ASA with packet tracert

I used 5506 as firewall and I am trying to delete object network I created and it gives error as ERROR: unable to delete the object configuration. object (inside-net-obj) is being used. commands I ...
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1answer
66 views

configure IPv6 ACL on interface WS-C3750X-48

I am using  WS-C3750X-48 model switch. license is lanbase. I have activated cmd on my switch: sdm prefer dual-ipv4-and-ipv6 routing. Then i did reload. After that, i will able to config IPv6 on ...
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1answer
39 views

Router Standard ACL

I was configuring Standard ACL on router 1841 on Cisco Packet Tracer with the help of command access-list 1 permit 172.16.40.3 0.0.0.0 and access-list 1 deny 172.16.40.4 0.0.0.0 and then I applied ...
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2answers
134 views

Nat ACL Question?

I am so confused with fundamentals that I used to be an expert in, so I have this topology Please answer to my questions separately, Question 1) So if I have two DNS severs, and ofc two IP address(81....
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1answer
166 views

Access control on Cisco router with switchports?

I am working with a series 800 router which has inbuilt switchports. I want to use 2 switchports for a VLAN (say VLAN 100). On one port will have devices: 192.168.1.10 192.168.1.30 Connected to ...
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1answer
188 views

how to send tcp packets between 2 hosts on same network

iam using mininet network simulation tool and i need to send tcp packets between 2 host hosts are 10.0.0.1,10.0.0.2 ,i used the hping3 but is sends ip packets also i used this command hping3 -c 1 [...
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3answers
451 views

How to add multiple ip address in destination ip in acl rule

Iam trying to block a certain host from sending any message to any host in the network is there is a way to do that or i have to deny host by host ?
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1answer
44 views

Using Extended ACL on destination instead of source

In the diagram we are required to block all the external user ping requests to the sever. For this I have created the following ACL on R1: access-list 105 deny icmp any any echo access-list 105 ...
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1answer
41 views

What interface would ACLs be under if two services were connected over a S-2-S VPN?

I am using the ADSM for ASA tool. I am trying to connect a service to a mysql server using port 3306. The service runs on a server that is on another network to the mysql server. It has been ...
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3answers
135 views

Using Standard or Extended ACL for Telnet Connections

In the picture shown the left bottom router is to be secured from any telnet requests. Now will I use Extended ACL on every router router or can I use the standard ACL just?
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3answers
85 views

ACL for DNS clarification

I do not understand why the second ACL is needed if all I want is to ensure all networks use a certain DNS server (for example 192.0.2.1) access-list 112 permit udp any host 192.0.2.1 eq domain ...
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1answer
62 views

How do I apply ACL in the given topology?

I am trying to understand the concept of standard and extended ACL. In the given topology, the top router is Front Desk(192.168.11.0/24). The left router is Nurses (192.168.7.0/24), left bottom is ...
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1answer
29 views

How to group 3 hosts in ACE Ipv6 statement

I know for ipv6 ACE there is no wildcard mask, so if I want to add three hosts in one statement, for example, which prefix should I use for that network? (network 2001:db8:cafe:1/64, ::1 reserved as ...
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1answer
45 views

ACL not blocking IP or ICMP packets out of an interface

I created this network to do some general practice. Every host on the network can ping every other host. The routers are just using a basic RIPv2 configuration. All of the interfaces can ping all the ...
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1answer
108 views

Create ACL for VLAN

I've multiple switches in LAN network environment configured with 3 VLANs, namely VLAN A, VLAN B and VLAN C. Since VLAN A is only allow to access internet without having accessibility to internal ...
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1answer
178 views

What can I use to block all the ports of the WAN in a Cisco router?

I have set up my small network using Cisco ISR C1111-8p and a Cisco Wireless AP C1832i. What can I use to block all the ports of the WAN? Is there any security advantage blocking them rather than ...
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1answer
957 views

Why does the Implicit Rule prevent traffic from passing?

I an testing traffic forwarding between different DMZ with different security levels. DMZ: interface GigabitEthernet0/1.351 vlan 351 nameif dmz security-level 10 ip address 10.100.20.1 255.255....
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2answers
468 views

Providing wildcard mask in extended ACL

Is it necessary to provide a wildcard mask in extended ACL? For example, if I want to block 192.168.5.2 from gaining access to 192.168.7.2, can I write the command as follows? access-list 107 deny ...
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1answer
33 views

source and destination in access-list

I am a bit confused in the concept of source and destination. Consider that I have to create an extended acl which blocks the access of 192.16.3.0/24 from 192.16.7.0/24. In this case my source is 192....
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1answer
31 views

Permit only WEB server in ACL on router? [closed]

In that topology I need to configure 192.168.1.0/24 will block 10.10.20.20 host 192.168.2.0/24 will block 10.10.10.0/24 network All users can view web page but can't ping etc ... I done that top 2 ...
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2answers
172 views

ACL: Deny specific host not working

I'm trying to create an acl for use with a nat but I can't get the deny statements working. All hosts on a private network should be accessible, except from a server which should not be accessible ...
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0answers
305 views

ACL to only output multicast traffic and allow IGMP messages back to router [closed]

In the EDIT, I have created a set of ACL so that an interface on router 1 can only allow multicast packets out to router 2 and allow for any IGMP messages to come into the router 1. Is what I have ...
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0answers
276 views

TCAM utilization on Nexus 9396 switches

I have Cisco Nexus 9396 switch which is running L3 mode and i have configured bunch of IPv4 access-list in Ingress for firewalling to block certain traffic. I am reading about TCAM and wanted to ...
3
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1answer
568 views

Allowing only routed traffic, block intra-VLAN forwarding

In a mixed network of Dell and HP/Aruba devices, we would like to block all communication between client computers, and only allow them to communicate with servers located on a different VLAN*. There ...
3
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1answer
304 views

Traffic not send in IPsec with a Cisco ASA

I try to set up a site to site IPsec between an Ericsson router and a Cisco ASA, as shown below: My tunnel is UP and R1 seems to be working fine. However, my ASA does not forward traffic between ...
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1answer
275 views

ASA access-list to object group

I'm not too familar with the ASA, is there a way to make this ACL into an object group and be easier to maintain? access-list VPN-ALLOCATIONS extended permit esp 172.16.1.128 255.255.255.252 172.16....
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1answer
426 views

L3 and L2 interfaces in ACL

What is L3 and L2 interfaces in ACL feature and why ethernet access-lists will not support L3 interfaces
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1answer
29 views

Issue with Connectivity Over Next Hop Gateway (ASA) to Point to Point

I'm having an issue routing traffic from a backup gateway on a different ISP, to our main gateway, which uses a point to point connection to a data center, with the majority of our infrastructure. ...
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1answer
23 views

ACL and ACEs Query

So i'm configuring a basic network and I need to create a couple of Extended ACLs. Now my question is, does this ACE permit any TCP connection to the following subnet? permit tcp 192.168.10.0 0.0.0....
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104 views

Block internet on a Cisco catalyst 3560 port

Good day Is there a way to block a specific port in a Cisco Catalyst 3560 switch to block the user from accessing the internet but still have full access to the internal corporate resources. The ...
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1answer
183 views

Can we apply ACL in default route?

I have default route setup as ip route 0.0.0.0/0 172.16.15.2 where 172.16.15.2 is internet connected router with NAT. Here is some snippet of the router configuration: interface GigabitEthernet0/...
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1answer
45 views

Exclude 10.63.128.0 10.63.255.255 or 10.63.128.0/17 range from 10.0.0.0/10

Please help to suggest a method to exclude IP range 10.63.128.0 10.63.255.255 from 10.0.0.0/10. I have a access list 3100 to filter the traffic with rule 10 10.0.0.0 0.63.255.255 and now I have to ...
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1answer
49 views

I can't connect to a denied network in Packet Tracer

I'm making a little practice in packet tracer and I'm configuring ACL. I want that the network call "Free WiFi Clientes" can not access to IT but when I deny that network in Router 3 I try to ping ...
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1answer
1k views

ASA5515 - QM FSM error / failed to establish L2L SA when transferring large files

I was hoping someone could help me with a problem I’m having - a little clarification or advice would be much appreciated: The Issue: I have set a new backup server and I want to back up data from ...

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