Solved

Remote teleworkers with CME

Posted on 2010-09-22
15
733 Views
Last Modified: 2012-05-10
Hi,

We have a Cisco 2811 ISR running CME 7.0. We do not use it as a router, only for voice.
Is there any *safe* way to allow remote teleworkers over the WAN? e.g. SIP clients securely authenticating to CME.
I know a possible solution is using VPN, but that creates a lot of overhead and is especially problematic on mobile platforms, so I'm wondering if it's possible to open some ports to CME and have clients connect directly (similar to public SIP providers).

Thanks in advance!
0
Comment
Question by:dilberty
  • 5
  • 4
  • 3
  • +1
15 Comments
 
LVL 34

Expert Comment

by:Istvan Kalmar
Comment Utility
Hi,

I advise to use VPN, becouse it is easy to crack the MD5 hashes of SIP!

0
 
LVL 9

Accepted Solution

by:
Alex Bahar earned 500 total points
Comment Utility
You can always create an ACL to allow ports 5060 and 5061 from your teleworker IP addresses. So non-teleworker IP addresses won't be able to register CME.
You can also use GRE tunnels, which will provide a very lightweight point to point VPN tunnels. It will make your life much easier. GRE tunnels can even carry routing updates if you're planning to run dynamic routing protocols on your remote sites.
0
 
LVL 2

Expert Comment

by:xReaper
Comment Utility
>> I advise to use VPN, becouse it is easy to crack the MD5 hashes of SIP!

Yes ? heh and how do you do that with complex password ?
0
 
LVL 34

Expert Comment

by:Istvan Kalmar
Comment Utility
HI,

Please try cain for hacking sip:

http://www.oxid.it/cain.html

it is working...
0
 
LVL 2

Expert Comment

by:xReaper
Comment Utility
Looks like you have no idea what are you are talking about here, this is such time when you better say nothing if you are not sure.
Do you have any idea how hash is used ?
You can bruteforce for ages, good luck.
0
 

Author Comment

by:dilberty
Comment Utility
Are you sure 5060 and 5061 are sufficient? don't I need UDP ports for voice?
0
 
LVL 2

Expert Comment

by:xReaper
Comment Utility
>Are you sure 5060 and 5061 are sufficient? don't I need UDP ports for voice?

Sure, but he talks about ACL, i think what he wanted to say thay you can use ACL for 5060, and open udp ports for averyone, anywas if sip dialog do not pass there is not point to add ACL to the rtp(udp) ports for voice.
And you dont need to use 5060 5061, use only one where your cme is binded to.
0
Why You Should Analyze Threat Actor TTPs

After years of analyzing threat actor behavior, it’s become clear that at any given time there are specific tactics, techniques, and procedures (TTPs) that are particularly prevalent. By analyzing and understanding these TTPs, you can dramatically enhance your security program.

 

Author Comment

by:dilberty
Comment Utility
Thanks guys. Is there any way to allow this only for specific users? Most of my users use simple passwords and besides I wouldn't want to allow them this functionality.
0
 
LVL 2

Expert Comment

by:xReaper
Comment Utility
Thats why you need ACL based on ip of your users. (external)
0
 

Author Comment

by:dilberty
Comment Utility
Users at home don't have a static IP address. It is assigned dynamically from the ISP, so I probably won't be able to achieve that...
0
 
LVL 9

Expert Comment

by:Alex Bahar
Comment Utility
For simplicity, you can assign an "allowed range of IP addresses/subnet" to the VOIP teleworkers. Let's call it white-list. You can then create a simple ACL that allows only that white-list ip address range access to the CME 5060 5061 ports.
0
 
LVL 9

Expert Comment

by:Alex Bahar
Comment Utility
Static IP addresses for home broadband cost only 2-3 dollars a month. It is worth getting it.
0
 
LVL 9

Expert Comment

by:Alex Bahar
Comment Utility
Another option is to use 2 different VPN groups which assigns IP addresses from 2 different pools> white-list and black-list IP address pools...
Thus, you can differentiate users even if they use dynamic IP addresses on their internet broadband.
0
 
LVL 34

Expert Comment

by:Istvan Kalmar
Comment Utility
HI,

I advise VPN.... it give more secure, and if you use g.728 or g.729 codec you able to use it without any problems! We use it over VPN...
0
 
LVL 9

Expert Comment

by:Alex Bahar
Comment Utility
IPSEC VPN is not bed of roses though. It introduces delay and bandwidth overhead.

Processing delay can be considerable if the WAN devices do not have hardware compression modules.

A single G729 voice stream over IPSEC VPN over DSL consumes about 67 kbps! Only 8kbps is the G729 payload. IPSEC VPN adds about 21kbps to a single voice stream.


0

Featured Post

What Is Threat Intelligence?

Threat intelligence is often discussed, but rarely understood. Starting with a precise definition, along with clear business goals, is essential.

Join & Write a Comment

Suggested Solutions

Title # Comments Views Activity
HP ProCurve and tagging 5 103
google voice, ring two phones 2 34
ASA 5505 Slowing Internet 11 120
Cisco VOIP 7941 6 78
Hey there Heard about jingle, the add on for XMPP that enables point to point audio between two XMPP clients. No server config necessary. Actually quite a cool feature. However, how good is it if you can not use those voice capabilities to do a P…
If your business is like most, chances are you still need to maintain a fax infrastructure for your staff. It’s hard to believe that a communication technology that was thriving in the mid-80s could still be an essential part of your team’s modern I…
Sending a Secure fax is easy with eFax Corporate (http://www.enterprise.efax.com). First, Just open a new email message.  In the To field, type your recipient's fax number @efaxsend.com. You can even send a secure international fax — just include t…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

772 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now