WatchGuard announces the acquisition of advanced authentication provider, Datablink, with one mission – to bring secure authentication to SMB, mid-market, and distributed enterprises with a cloud-based solution, ideal for resale via their established channel & MSSP community.
COURSE of the MONTH
7 days, 23 hours left to enrollBecome a Premium Member and unlock a new, free course in leading technologies each month.
Solved
Use Access lists on mpls network, but now can't access internet
Posted on 2008-06-11
Ok Here it goes....
I found a network on our mpls link that isn't ours in our routing tables. So I am trying to put access lists on the switches at all our locations. However, when I apply the access lists all the internal networks can talk, but nothing can go out to the internet. I thought that I could put a rule to allow any traffic out but the switch will only allow you to apply an access group in. Besides that I don't know if cisco keeps track of sessions. ie. if a packet is allowed out, is it allow to receive the ack if theres no rule to specifically allow that ip?
Ok so heres what I have setup.
access-list 1 permit 10.10.0.0 0.0.255.255
access-list 1 permit 192.168.0.0 0.0.255.255
access-list 1 permit 172.16.0.0 0.0.255.255
I have tried applying the group on all ports of the switches and just the vlans.
It can traverse the mpls but won't allow you to go out to the internet.
I tried making a rule to allow any traffic and apply it to an interface out but there is no out command.
On the 3750s' I'm running 12.2(40)SE and on the 2960s' I'm running 12.2(25)see3.
Is there some kind of command you need to remember sessions or something?
I found a network on our mpls link that isn't ours in our routing tables. So I am trying to put access lists on the switches at all our locations. However, when I apply the access lists all the internal networks can talk, but nothing can go out to the internet. I thought that I could put a rule to allow any traffic out but the switch will only allow you to apply an access group in. Besides that I don't know if cisco keeps track of sessions. ie. if a packet is allowed out, is it allow to receive the ack if theres no rule to specifically allow that ip?
Ok so heres what I have setup.
access-list 1 permit 10.10.0.0 0.0.255.255
access-list 1 permit 192.168.0.0 0.0.255.255
access-list 1 permit 172.16.0.0 0.0.255.255
I have tried applying the group on all ports of the switches and just the vlans.
It can traverse the mpls but won't allow you to go out to the internet.
I tried making a rule to allow any traffic and apply it to an interface out but there is no out command.
On the 3750s' I'm running 12.2(40)SE and on the 2960s' I'm running 12.2(25)see3.
Is there some kind of command you need to remember sessions or something?
[X]
Welcome to Experts Exchange
Add your voice to the tech community where 5M+ people just like you are talking about what matters.
- Help others & share knowledge
- Earn cash & points
- Learn & ask questions
2-
2
4 Comments
OK, first you would need to put an allow any statement in as there is an implicit deny at the bottom of every access list.
Second to block the other networks you would need to put the deny at the TOP of the ACL. It would be more efficient to put it like this:
access-list 1 deny ip [unknown network]
access-list 1 permit ip any any
That will let your networks talk to each other and to the internet. The deny statement will be read and processed for the traffic you don't want and will drop it before it gets to the permit stage.
The "in" part of the command means into the interface, not the network. If you were to put that ACL into your edge interfaces you should be fine.
Second to block the other networks you would need to put the deny at the TOP of the ACL. It would be more efficient to put it like this:
access-list 1 deny ip [unknown network]
access-list 1 permit ip any any
That will let your networks talk to each other and to the internet. The deny statement will be read and processed for the traffic you don't want and will drop it before it gets to the permit stage.
The "in" part of the command means into the interface, not the network. If you were to put that ACL into your edge interfaces you should be fine.
I can see that this would work but if I start putting deny statements in then if another new network happens to pop up and I don't know about it the default would be to allow all traffic. Isn't there a way to do this with a default deny rather then default permit?
No. You need a default to allow any as you do not know to which addresses you will be sending internet traffic. The closest you could probably be come would be:
permit YOUR networks
deny 10.x
deny 192.x
deny 172.x (basically put in deny rules for all PRIVATE subnets)
permit any (to allow access to the internet)
permit YOUR networks
deny 10.x
deny 192.x
deny 172.x (basically put in deny rules for all PRIVATE subnets)
permit any (to allow access to the internet)
Featured Post
Question has a verified solution.
If you are experiencing a similar issue, please ask a related question
Phishing is at the top of most security top 10 efforts you should be pursuing in 2016 and beyond. If you don't have phishing incorporated into your Security Awareness Program yet, now is the time. Phishers, and the scams they use, are only going to …
Envision that you are chipping away at another e-business site with a team of pundit developers and designers. Everything seems, by all accounts, to be going easily.
If you're a developer or IT admin, you’re probably tasked with managing multiple websites, servers, applications, and levels of security on a daily basis. While this can be extremely time consuming, it can also be frustrating when systems aren't wor…
Visualize your data even better in Access queries. Given a date and a value, this lesson shows how to compare that value with the previous value, calculate the difference, and display a circle if the value is the same, an up triangle if it increased…
Suggested Courses
Course of the Month7 days, 23 hours left to enroll
765 members asked questions and received personalized solutions in the past 7 days.
Join the community of 500,000 technology professionals and ask your questions.