Currently set in Aggressive mode. 1 side has keep alives every 60 seconds
Main Topics
Browse All Topics
Loading Advertisement...
Question
Site to Site VPN tunnel issues
Scenario: 2 sites 1 Domain
Main office:
Watchguard Firebox X Edge
MS Small Business Server 2003 w/ Exchange
30-40 windows XP professional clients
T1
192.168.2.x subnet
Remote office:
Fortigate 60
10-20 windows XP professional clients
DSL
192.168.3.x subnet
There is a site-to-site VPN setup between the two firewall devices. Remote office workers access shared folders and e-mail over the VPN tunnel. VPN tunnel has been shutting down every couple weeks. I've been able to solve this by logging into each VPN device and refreshing the IPsec keys and/or resetting the remote office firewall. Once the tunnel is active connectivity returns to normal. The settings are DH5, Sha-1, 3DES-CBC pre-shared key. key exprires every 24 hours.
Any ideas why the tunnel would break intermittently? Today was the most recent occurence of this event and I've been able to get the tunnel backup with a reboot on the Fortigate60 at the remote site. But now remote office clients cannot access shared files or network drives. Tunnel status is showing as active on both devices
Also the Watchguard at the main site will intermittently freeze every few weeks, requiring a reboot. There's no common interval. Sometimes it will be up for 6 weeks some times 4 or 5 days.
I've heard that malware can cause buffer overflows and wierd gateway problems. I've been logging events on the watchguard to verify my suspician but haven't seen anything conclusive yet.
This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.
Subscribe now for full access to Experts Exchange and get
Instant Access to this Solution
- Plus...
- 30 Day FREE access, no risk, no obligation
- Collaborate with the world's top tech experts
- Unlimited access to our exclusive solution database
- Never be left without tech help again
Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.
- "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
- "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
- "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.
See what Experts Exchange can do for you.
Got a question?
We've got the answer.
Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.
Need individual assistance?
Our experts are ready to help.
If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.
Want to learn from the best?
Read articles from industry experts.
Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.
Working on a long term project?
Store your work and research.
Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.
Access the answers to your technology questions today.
30-day free trial. Register in 60 seconds.
What Makes Experts Exchange Unique?
Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.
Trusted by the world's most respected brands.
Faithfully serving IT professionals since 1996.
Try it out and discover for yourself.
30-day free trial. Register in 60 seconds.
Free Tech Articles
-
WARNING: 5 Reasons why you should NEVER fix a computer for free.
It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
-
SCCM OSD Basic troubleshooting
SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
-
Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
-
Create a Win7 Gadget
This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
-
Outlook continually prompting for username and password
There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
-
Backup Exchange 2010 Information Store using Windows Backup
There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...
Cloud Class Webinars
- Avoiding Bugs in Microsoft Access
Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
- Top 10 Best New Features in Visio 2010
Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
- IT Consultant Business Secrets Revealed
Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
- Disaster Recovery and Business Continuity
Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
- Organize Your Visio Diagrams with Containers and Lists
Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
- How to Us Objects, Properties, Events and Methods in Microsoft Access
Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...
Join the Community
Give a Little. Get a Lot.
Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.
Answers
IPSec tunnels can drop for the following reasons:
The SA's can be mismatched (even though the tunnel has been up for months) i.e
some IPSec tunnel access-lists if not exactly matched by subnet and networks can caused dropped tunnels (using a network name for one subnet and using the actual subnet ip on the other peer can cause this)
mismatch in keepalive values
ISAKMP Lifetime (you see this in syslogs with error messages stating rekeying attempts)
I would only change the MTU's as a last resort, if nothing else seems to work. MTU changes usually are a result of router issues, or when the following happens with applications thru an IPSec tunnel:
MTU's become issues when hosts have trouble with certain apps, ie. exchange server and graphics programs which have large data packets which exceed the mtu's of the firewall. When ESP headers are added to the data packets, the packets often exceed the mtu of the firewall with the DF (don't fragment bit) cleared, and the packets don't get fragmented. These type of issues will involve changing the mtu of the firewalls as well as the MSS (maximum segment size) of the packets
Make sure order of transform sets on both piers are identical as well as the sets themselves being identical.
syntax of Phase 1 (ISAKMP) on both peers
NatExempt access lists must be identical as well as the syntax (always use the command line over the gui to verify this)
Verify routing tables also - if you cannot ping hosts, then there is a problem with
routes and or natexempt lists.
tunnel seems to be working currently. Although users in the remote office cannot access anything on the main office network. no pings, no outlook, no rdp. I'll double check the NAT entries. But these have not changed. Why would the be working (intermittently) for 6-9 months and then stop working. DHCP isn't enabled for the external interfaces on either device. and the local and remote subnets are specified correctly on both devices.
The only thing that changed over the weekend was a scheduled downtime to rearrange some power cords and UPS connections. No software was altered. The tunnel status is Active.
do a clear xlate in global mode after hours - to clear all the NAT translation slots. In some cases, you can try removing and re-applying the crypto maps.
Again, I have seen instances of tunnels functioning flawlessly for months and then just drop. Had some drop on me this week at a location -- it turned out I had to reapply the access-lists in both nat exempt and acl's. I used the numerical ip notation on the opposing peer, which had a network object group syntax mapping to the allowed networks. placing the numerical ips back in the config brought the tunnel back up
something to try at least
3 Ways to Join
Business Accounts
- Perfect for organizations
- Multiple users
- Save over 36%
- Create a Business Account
Answer for Membership
- Earn free access
- Showcase your knowledge
- No credit card required
- Sign Up to Answer
Loading Advertisement...
by: ccpjcPosted on 2009-10-19 at 13:45:14ID: 25608849
I don't have experience with these firewalls, but usually VPN's are somewhat the same
I'm going to assume that you have static IP's assigned on each side, if not there's one thing to look at
Are the VPN's set to Main mode or an Aggressive mode?
Do you have a keep alive option on the firewalls, perhaps somewhere in the advanced, if so, enable it only on one side of the sites not both
play with the expiring of the pre-shared key
Change the MTU settings on the firewalls from 1500 to 1404, seems to work good with a lot
Ensure that both sides of the VPN tunnels have the same settings, sha-1, 3des, etc...