July 7, 2017 / Greg / 0 Comments
I’ve had an IPv6 tunnel from HE.net for quite some time now. Back when I was running the ASA 5505 as my edge, I had to put a router behind it to create the tunnel. Then, when I replaced the ASA with an SRX 220 back in December 2015, I was able to build the tunnel natively on the SRX. Since that time, Time Warner has gotten around to providing IPv6 in my area and I’ve tried a couple different times to get it working with no luck. Now, I’ve finally decided that I wasn’t going to stop working on it until I got it working, and I’ve done just that, so it’s time to tell you guys how to do it yourself.
First a few caveats… Obviously, Time Warner (now Spectrum) needs to provide IPv6 in your area and that your modem supports it. I don’t remember how I found out that they finally had it here, but it was probably a fellow network engineer at TWC that told me. Second, realize that you’re going to have to reboot the SRX, so you’re going to lose connectivity for a bit. The reason you’ll need to reboot is that we need to enable IPv6 flow mode, otherwise the SRX will just drop IPv6 traffic. Let’s start with that…
Obviously, ssh into the SRX and enter config mode. Then enter the following command:
set security forwarding-options family inet6 mode flow-based
Then you’ll need to reboot with “request system reboot”. Once it comes back up, you’re ready to move on.
Your ge-0/0/0.0 interface probably looks something this at present:
greg@SRX220H# show interfaces ge-0/0/0.0
description “Uplink to Cable Modem”;
family inet {
dhcp;
}
We’re going to need to change the dhcp daemon that you’re using on that interface because if we were to continue on with what’s coming, you’d get an error. Then we’re going to add the ipv6 dhcpv6-client config to the same interface. Here’s your commands:
delete interfaces ge-0/0/0 unit 0 family inet dhcp
set interfaces ge-0/0/0 unit 0 family inet dhcp-client
set interfaces ge-0/0/0 unit 0 family inet6 dad-disable
set interfaces ge-0/0/0 unit 0 family inet6 dhcpv6-client client-type statefull
set interfaces ge-0/0/0 unit 0 family inet6 dhcpv6-client client-ia-type ia-na
set interfaces ge-0/0/0 unit 0 family inet6 dhcpv6-client client-ia-type ia-pd
set interfaces ge-0/0/0 unit 0 family inet6 dhcpv6-client client-identifier duid-type duid-ll
set interfaces ge-0/0/0 unit 0 family inet6 dhcpv6-client update-router-advertisement interface vlan.0
Now we need to set our firewall to allow some traffic:
set security zones security-zone untrust interfaces ge-0/0/0.0 host-inbound-traffic system-services dhcpv6
set security zones security-zone untrust interfaces ge-0/0/0.0 host-inbound-traffic protocols router-discovery
That should be pretty self explanatory. You need to allow dhcpv6 through the firewall for all this to work, and we’re going to use router-discovery to figure things out. Once you commit that, the SRX should ask TWC for an IPv6 address. Let’s check to see if we got one…
greg@SRX220H# run show dhcpv6 client binding
IP/prefix Expires State ClientType Interface Client DUID
2607:fcc8:ffc0:5:14c9:b140:XXXX:XXXX/128 600553 BOUND STATEFUL ge-0/0/0.0 LL0x3-54:e0:32:ec:XX:XX
2605:a000:XXXX:XXXX::/64 600553 BOUND STATEFUL ge-0/0/0.0 LL0x3-54:e0:32:ec:XX:XX
It looks like we have an address! Now, we need to add a route… we’ll find our next hop by running the previous command and adding detail:
greg@SRX220H# run show dhcpv6 client binding detail
Client Interface: ge-0/0/0.0
Hardware Address: 54:e0:32:ec:XX:XX
State: BOUND(DHCPV6_CLIENT_STATE_BOUND)
ClientType: STATEFUL
Lease Expires: 2017-07-14 08:01:52 EDT
Lease Expires in: 600551 seconds
Lease Start: 2017-07-07 08:01:52 EDT
Bind Type: IA_NA IA_PD
Client DUID: LL0x3-54:e0:32:ec:XX:XX
Rapid Commit: Off
Server Ip Address: fe80::201:5cff:fe78:XXXX
Client IP Address: 2607:fcc8:ffc0:5:14c9:b140:XXXX:XXXX/128
Client IP Prefix: 2605:a000:XXXX:XXXX::/64
DHCP options:
Name: server-identifier, Value: LL_TIME0x1-0x1d7c50b0-00:50:56:XX:XX:XX
Yes, the lease started about an hour before I posted this. I was so excited that I had to post immediately! Anyway, we’re looking for that Server IP Address. Once we have that, let’s add a static route to it.
set routing-options rib inet6.0 static route ::/0 qualified-next-hop fe80::201:5cff:fe78:XXXX interface ge-0/0/0.0
The qualified-next-hop is going to give you a lot more control over a standard next-hop. Commit the config. Once everything is committed, it’s time to test, so we’ll ping Google’s DNS server.
# run ping 2001:4860:4860::8888
You should get a response. IPv6 is now working! W00T! In order to get your network clients talking to the internet on IPv6, you’ll have to configure them to use IPv6. As you can see up above in the dhcpv6 client binding detail, there’s a “Client IP Prefix”. That’s the prefix assigned to you. If you do a “run show interfaces vlan.0 terse”, you’ll see that it now has an inet6 address that looks like 2605:a000:XXXX:XXXX:1::1/80. That’s going to be your IPv6 router / gateway address. You can statically assign IP’s by just counting up from that last ::1, so assign 2605:a000:XXXX:XXXX:1::2/80 to your workstation and try to ping 2001:4860:4860::8888. If you get a response, you’re good to go.
So, that’s the commands I had to enter to get IPv6 working on my SRX. YMMV depending on TWC’s configuration in your area, but this should get you pretty damn close.
August 3, 2010 / Greg / 1 Comment
In my last post I taught you how to forward a port on the ASA 5505 running version 8.3 from the CLI. Some of you prefer to use the ASDM to do you changes, so I guess I’ll show you how to do it from there. The ASDM is a bit of a learning curve for someone that’s used to the CLI, and most CLI guys hate a GUI with a great passion. I can go either way. I use the ASDM to make some changes simply because I want to learn it and there’s some guys coming into the field today that were taught on the GUI rather than a command line.
In this lesson I’m using ASDM version 6.3(1) and ASA version 8.3(1). Since we added a web server in the last post, let’s make this one an FTP server. The FTP server’s IP is the same as the web server, 10.9.8.7/24 and we’re running over the standard FTP port, 21.
First off, we want to start up the ASDM and connect to the ASA. Once there, click on the 
button at the top of the screen, then the 
button near the bottom left, and finally select 
near the top left. You’ll now be at a screen that looks something like this:
Click for larger version
Now we need to create a new object, so click on “Add” under Addresses, then “Network Object”.
Now we need to fill out our new window. Once you fill out the name, IP address and description, you need to drop down the NAT box and fill it out. Click the “Add Automatic Address Translation Rules” box, leave the type as “static” and set the translated address as the outside interface.
We now need to go to the Advanced menu from the Add Network Object window and setup the port forwarding. The source will be inside, destination is outside. Protocol in this instance is TCP and our port is 21, both real and mapped.
Click “OK” twice and your object will be created as well as the port forward. Now we just need to add the access rule. On the left side of the screen, just above the NAT Rules is your Access Rules. From there we want to click “Add” and “Access Rule”.
We need to create the rule on the outside interface, coming from any IP to the FTPServer using FTP as the service.
Once you click OK, your rule is added. You don’t have to add a description like I did in the image above this one, I just did that for the hell of it. When you click “Apply” at the bottom of the screen, the ASDM will issue the commands to the ASA. I have preview turned on, so I can always see what commands are being sent to the device before they are actually sent. If you followed all the steps above and you have preview turned on, you’ll see the following:
And you’ll notice that those are the exact 4 commands that I gave in the last post about doing it from the CLI! Now you can forward any port you want from either the CLI or the ASDM!
On a side note, I know a lot of guys hate the ASDM. When I was writing this post and going through all of this I was kinda upset when I saw that I had 10 pictures for 4 lines of code. The good thing about the ASDM is that you have everything right there at your disposal and you really don’t need to know the vernacular of IOS. The drawback is that it will take you longer to get things done at first, but once you get used to it, it can be just as fast.
August 3, 2010 / Greg / 1 Comment
So it’s been a month and a half since I posted an update, and it’s 4:15 am right now. I can’t sleep and I found out there’s another networking blog out there using the same WP theme as me, so I figured I better put something up here since it was fresh in my mind. Well, now that the niceties are out of the way, let’s get to work.
I recently added an ASA 5505 to my home network at the edge. Obviously, when I did, all of my port forwards went to hell because the ASA is now blocking everything. I run a web server on one of my servers here and I like to be able to access it because I keep a lot of tech manuals and other stuff on there. Well, I went about trying to set up port forwarding the old way and learned real quick that this pops up when I do:
ERROR: This syntax of nat command has been deprecated.
Please refer to “help nat” command for more details.
Yeah, that sucks. On the new version of the ASA OS, global has gone the way of the dodo. I did a bunch of searches on Google to figure it out and everything I ran across was very hard to decipher. That’s why I’m writing this. You can setup a port forward in 4 quick and easy steps. Just change the things that are underlined to fit your network and you’ll be just fine.
In this example, we want to be able to access a web server behind the firewall. We’ll assume you are using the standard HTTP port, the web server’s internal IP address is 10.9.8.7/24, and that you at least know what you’re doing enough to be configuring an ASA in the first place. I’ll give you the steps, then I’ll explain.
Step 1: Create a new object group for you web server.
asa5505(config)# object network Webserver
Step 2: Add the IP of the web server to the network group.
asa5505(config-network-object)# host 10.9.8.7
Step 3: Forward the port via the NAT command.
asa5505(config-network-object)# nat (inside,outside) static interface service tcp www www
Step 4: Exit back to the root and add the access list
asa5505(config)# access-list outside_access_in permit tcp any object Webserver eq www
That’s it! Now, let’s explain what’s going on here. Cisco has started moving more and more towards use of object groups in their configs. It makes things easier, especially when you have a situation where you have 20 web servers behind the firewall and you want to add 1 more in. Rather than having to rewrite a whole bunch of ACL’s, you just add the IP of the new web server into the object group and everything is done for you. After you create the object group (in this instance a network object, you can also create service objects), you add the IP of the specific object (or objects) that you want to point to. So here our web server is 10.9.8.7. If you want to send port 80 to more than 1 IP on your internal network, just add more IP’s to that object group.
Now is the fun part. While we’re in the object group, we need to NAT port 80 only to that specific object group, hence you’re still at “asa5505(config-network-object)#” prompt. Now type “end” to get back to the regular config terminal and we need to open that port in the ACL. Yes, www = 80. You can type either one and you get the same result. If I have to go through and explain NAT, how it works and why I enter in that specific command to forward the port, then there’s a possibility that I’d need to send you an invoice for my time because we would be here for a while.
This works for ANY port forward. If you want to RDP into a machine, simply replace port 80 (all those www’s you see up there) with 3389. There is one caveat. You can only do one port forward per object group. So let’s say that our web server is also an FTP server and you want port 21 to forward as well as port 80. You’re going to have to create a whole new object group (object network FTPServer), put the same IP in the group (host 10.9.8.7), do the nat command again (nat (inside,outside) static interface service tcp ftp ftp), exit back to the root of config, and add the access list (access-list outside_access_in permit tcp any object FTPServer eq ftp).
This should get you up and running with you port forwards in no time flat. It is a bit of a pain in the ass to have to create a new object group for every port you want to forward, and maybe there’s someone out there that’s reading this right now thinking “dude, you don’t have to create more than one group! You can just do…”. Well, you need to enlighten the world with this knowledge and post it in the comments section. And if you’re too scared to do so, shoot me an email to greg(at)gregledet(dot)net.
I’d also like to thank Stefan Fouant for an excellent class today on JUNOS Switching. I learned a lot in his class and you can learn a lot from his website. Check it out and tell him Greg sent ya!
