Access-control list
32
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11
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Search complete. 32 mentions across 11 episodes found for "Access-control list".
Oct 15, 2026
Ethan BanksHOST
One of those actions might be permitting or denying traffic, and maybe that's the most common use case that you run into, but you can do a lot of other things, and so we're going to talk through some of that.
Ethan BanksHOST
Classification, what do we mean by classifying traffic? Typically, when you're reading about access lists, ACLs, classification is done by examining information in layers three and four.
Ethan BanksHOST
So when I say layer three, four, Holly, what do you think of?
Holly PodbielakHOST
I think about, why are we talking about layer two? But you think about things like IP addresses, protocols, destination and source ports.
5 MINS LATER
Holly PodbielakHOST
We did a lot on the SRX.
Holly PodbielakHOST
So just practicing those firewall filters.
Holly PodbielakHOST
I didn't have that many customers doing security, but ACLs came up all the time.
Holly PodbielakHOST
I think a lot of the time it was on those Cisco switches.
Ethan BanksHOST
Um, and- Classification.
Ethan BanksHOST
What do we mean by classifying traffic? Typically, when you're reading about access list, ACLs, uh, classification is, is done by examining information in, in layers three and four.
Ethan BanksHOST
So when I say layer three/four, Holly, what do you, uh, what do you think of?
Holly PodbielakHOST
[laughs] I think about why aren't we talking about layer two? Um-
6 MINS LATER
Ethan BanksHOST
Mm-hmm
Holly PodbielakHOST
...
Holly PodbielakHOST
but ACLs came up all the time.
Holly PodbielakHOST
I think a lot of the time it was on those Cisco-
Ethan BanksHOST
And so, so we're, we're gonna talk through some of that.
Ethan BanksHOST
Um- Classification, what do we mean by classifying traffic? Typically, when you're reading about access list, ACLs, uh, classification is, is done by examining information in, in layers three and four.
Ethan BanksHOST
So when I say layer three, four, Holly, what do you, uh, what do you think of?
Holly PodbielakHOST
[laughs] I think about why aren't we talking about layer two? Um-
6 MINS LATER
Ethan BanksHOST
Mm-hmm
Holly PodbielakHOST
...
Holly PodbielakHOST
but ACLs came up all the time.
Holly PodbielakHOST
I think a lot of the time it was on those Cisco-
speaker_4HOST
The perimeter guards of the network.
speaker_5HOST
They are, and they utilize access control lists, or ACLs, to ruthlessly filter incoming and outgoing traffic.
speaker_5HOST
Remember our tennis ball analogy?
speaker_4HOST
Yeah, throwing them at the wall.
Herman PoppleberryHOST
It's protecting nothing because nothing reaches it.
Herman PoppleberryHOST
Any policy you relied on there has to be rebuilt as ACLs on the switch.
Herman PoppleberryHOST
That's the single most common Layer 3 mistake.
Herman PoppleberryHOST
People enable routing, feel the speed, and never think about where the packets stopped going.
CornHOST
To say the obvious thing directly, replacing a firewall with a Layer 3 switch is a security downgrade, not a consolidation.
Herman PoppleberryHOST
It isn't a consolidation.
Herman PoppleberryHOST
A switch with ACLs isn't a firewall.
Herman PoppleberryHOST
It doesn't do stateful inspection.
Abhi ShamsudarGUEST
Talking very strictly, very traditional functions.
Abhi ShamsudarGUEST
You write ACLs.
Abhi ShamsudarGUEST
Unless you start doing Mac-to-Mac ACLs, then if, which is not scalable, anything in Traviland has always been a function of, you know, some form of tagging to prevent tag-to-tag conversation.
Abhi ShamsudarGUEST
But, you know, it has served us well.
Abhi ShamsudarGUEST
Until IP spaces have started exploding, you can't keep up with the amount of IP subnets you create.
Abhi ShamsuddharGUEST
Ta-talking very str-strictly very, uh, traditional functions.
Abhi ShamsuddharGUEST
Uh, you write ACLs, uh, unless you start doing MAC-to-MAC, uh, [chuckles] ACLs, then if, if it's not scalable, uh, anything inter VLAN has always been a function of, uh, you know, some form of tagging to prevent that, that conversation.
Abhi ShamsuddharGUEST
But-
Drew Connery-MurrayHOST
Uh-huh
Abhi ShamsudarGUEST
Talking very strictly, very traditional functions.
Abhi ShamsudarGUEST
You write ACLs.
Abhi ShamsudarGUEST
Unless you start doing Mac-to-Mac ACLs, then if, which is not scalable, anything in Traviland has always been a function of, you know, some form of tagging to prevent tag-to-tag conversation.
Abhi ShamsudarGUEST
But, you know, it has served us well.
Abhi ShamsudarGUEST
Until IP spaces have started exploding, you can't keep up with the amount of IP subnets you create.
BaluHOST
Network ACLs, on the other hand, operate at subnet level and are stateless, meaning you must explicitly allow both the inbound and return traffic with separate rules.
BaluHOST
And NACLs support both allow and deny rules.
BaluHOST
Stateful and instance level is a security group.
BaluHOST
Stateless and subnet level is an NACL.
Jack KlechaGUEST
hundreds of sites globally, numerous data centers, a lot of cloud infrastructure, and that's what, millions of ACL lines?
John WoolwineGUEST
Millions of lines of ACLs, yeah.
Jack KlechaGUEST
And now we're talking, throw in exponentially more agents talking to themselves, talking to more data sources, and we can't scale our ACLs that far.
Jack KlechaGUEST
But these
John WoolwineGUEST
agents are coming and going and moving around, so static policy is not going to work.
Jack KlechaGUEST
It's like, go now.
John WoolwineGUEST
So, okay, thinking a little bit about just policy and the network, today's world is largely human-driven.
John WoolwineGUEST
We've got millions of lines of ACLs.
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