Trying to Identify Unknown Firewall Traffic

Posted on 2013-06-21
Medium Priority
Last Modified: 2013-06-26
About once or twice a day I am seeing something like this in the any -> any rule from the inside interface:

6|Jun 21 2013|08:05:25
access-list inside_access_in permitted tcp inside/ -> WAN/ hit-cnt 1 first hit

6|Jun 21 2013|08:05:25
access-list inside_access_in permitted tcp inside/ -> WAN/ hit-cnt 1 first hit

None of our network or VLANS use this inside IP range so I'm not clear on how this can be routed in our network or sent out the firewall.  I tried doing a search on the and it only comes back to a RackSpace address.

I also did some searching on port 5223 and it seems to be used by Apple/Iphone products.  

Right now, our any -> any rule is set to allow on the inside interface because we are still testing restricting outbound access but it will soon be set to deny.  I'm just curious where this traffic is coming from and how it's getting out with this IP address.

Anyone familiar with this?
Question by:AllDaySentry
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LVL 25

Expert Comment

ID: 39266530
is it always to and port 5223?  What do you have for a firewall?  Do you have a managed switch?

What I'm thinking is have you perform a capture either from the firewall (if its capable) using an ACL to restrict what gets captured or if you have a managed switch you can mirror the firewall traffic to a different switch port, plug a computer into it and sniff the traffic.  After it happens again look at the traffic at that time to see if you can spot the protocol being used.

also, maybe via arp table lookups you can find out the MAC of that client.  see if its an apple device of some sort.  maybe find out if its an iOS device because like you saw 5223 should be something related to apple's push notification

Expert Comment

ID: 39266569
I think you are on the right track here. Port 5223 is used by Apple primarily for iCloud, but also for MobileMe, APNs, FaceTime, etc. You most likely have users in your company that have their devices connected to your network. When you block the port they will experience connectivity issues (unless they disconnect from the network and use 3G/4G).

I can't explain the rackspace IP, perhaps one of the users has hosted email account or something similar with rackspace on their phone or tablet.

Author Comment

ID: 39266573
Yes, the traffic is always to on port 5223.  The inside IP changes but its always a 10 address:,, etc.

We are using a ASA 5510 firewall.  We have a 3750 switch that does our internal L3 routing using subnets internally and we have one subnet.

Its only a couple hits a day and we are going to be setting the any -> any to deny soon but I'm confused how this even gets routed and where it's coming from.
LVL 25

Accepted Solution

Cyclops3590 earned 1000 total points
ID: 39266594
In that case, you can run a capture from the ASA then:


do an acl with two rules to match
any > eq 5223 eq 5223 > any

Sounds like you shouldn't have anything to worry about.  The capture will be able to tell you for sure.  I have to wonder if it will just be dropped though when trying to leave the inside interface as there is no route is my guess.  It might also be hairpinning you're seeing if you have same-security intra-interface turned on as the default route on the ASA would pry force it back out the outside interface. not really sure.  if nothing else, after  you get capture from the outside and inside interface (you should do two capture sessions) you might find out enough to run a packet-tracer to see exactly what rules are being hit and if it somehow does match a routing rule you're not expecting it to match

Author Closing Comment

ID: 39279026
I think you are right.  Its most likely hairpinning.  After reviewing the logs it does not look like any meaningful traffic.

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