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FG_User
New Member
February 15, 2012
Question

Internal DNS name resolution not working

  • February 15, 2012
  • 14 replies
  • 14716 views
We' re using SSL VPN with split tunneling enabled. In the VPN DNS and WINS server names I put our two systems which provide those services. However when using the bookmarks or connection tool I cannot connect via the name of the system. Neither hostname or FQDN works. Only via IP. Obviously most users don' t know the IPs of the systems.

    14 replies

    rwpatterson
    New Member
    February 15, 2012
    Welcome to the forums. Split tunneling is like that. If you force all traffic through the firewall, you' ll find it works as desired. If you don' t have a big pipe at the FGT end, you may find the web browsing is choking production.
    FG_User
    FG_UserAuthor
    New Member
    February 15, 2012
    So there is no way to do this without disabling split tunneling? No dns tricks or anything else? This seems crazy.
    emnoc
    New Member
    February 15, 2012
    The split-dns feature is your friend but I don' t know of how it' s depeloyed in the fortigate dessgn. But correct me if I' m wrong, is it your clients or is it the SSLVPN ( fortigate) conducting the dns-lookup for the bookmark address? You can validate that the appliance has a dns server applied or use the nslookup tool to see what dns-server your using.
    Maik
    New Member
    February 15, 2012
    However when using the bookmarks or connection tool I cannot connect via the name of the system
    From that, I read that you are using the bookmarks from the SSL VPN web portal. We are not talking about browser bookmarks. SSL VPN Web Portal Adresses are resolved by the Fortigate itself. Did you configure your Fortigate to use the internal DNS Servers? regards Maik
    FG_User
    FG_UserAuthor
    New Member
    February 15, 2012
    @EMNOC: Under VPN > SSL > Config ... Advanced > I put in the two dns servers ip addresses and WINS servers. @MAIK: Yes, by bookmarks I am refering to the SSL VPN portal bookmarks, not local ones on a user' s machine.
    Carl_Wallmark
    New Member
    February 15, 2012
    It is the fortigate itself who does the dns lookup NOT the dns in the ssl config. You need to enter an internal dns under System -> Network -> DNS
    veechee
    New Member
    February 15, 2012
    This doesn' t answer your question, but provides some of my experience with split tunneling. I used split tunneling in production for about 5 users for several months but I removed it from use because there are so many DNS tricks and hacks out there these days, that I couldn' t make internal resources work 100% reliably with it. The problems I ran into were at places like airports or hotels where there is a captive portal before access is granted. Often these types of sites enforce certain DNS servers and that messes up the split tunnel, leading to security warnings for internal resources or outright failures. Also, we use SaaS email and if there is a latency or other connectivity issue using the local Internet connection, getting onto the full tunnel usually restores access. I' m in the initial stages of looking at MS DirectAccess to provide always on internal network resources and local internet. The technology behind DA is such that it should allow both to work reliably (but it' s very complicated to get set up).
    emnoc
    New Member
    February 15, 2012
    Cisco ASA has a split-dns feature that get' s thru these issues hurdles and allows the client to resolve only domainnames allowed for that vpn client. I' m surprise that fortigate does not have this function. For the op FGUser, now that it' s confirm the fortigate looks up the SSLVPN bookmarks, can you answer the questions of , " does the fgt have your inside local dns-servers configured?"
    FG_User
    FG_UserAuthor
    New Member
    February 15, 2012
    @SELECTIVE: 1. What is the point of the SSL VPN DNS settings then? 2. Our Prof Services installer for the units put 8.8.8.8 and the DNS server from our ISP as the ones to use in that system. Should I replace them with our internal DNS servers (which themselves point out to those two IPs anyway for their external DNS lookups)? He said specifically that we should avoid sending DNS lookup requests from the Fortigate to our internal DNS servers (our DCs have DNS role as well). THanks!
    FG_User
    FG_UserAuthor
    New Member
    February 15, 2012
    I guess if there was some way to make sure streaming media from VPN users didn' t hose our system that' d be ok to turn it off. My main goal was to keep any unnecessary traffic/resources off the units. Especially if a home user' s system is messed up and has malware using it to send smtp traffic or something else. You get the gist. Why send youtube traffic over the vpn, right?