PPTP Server

Discussion in 'DD-WRT Firmware' started by mjkidd, Apr 27, 2005.

  1. mjkidd

    mjkidd Network Guru Member

    I have PPTP server working but two issues that I cant solve.

    First is DNS - PPTP supplies a DNS server ( to the client but does not repsond to DNS requests, suspect this is a firewall issue ? This causes problems for some lookups even when the client is split tunneling.

    Second issue is CPU usage the pptpctrl process never sleeps and consumes all available CPU when a tunnel is up :-

    19252 root R 304 19250 98.0 1.0 pptpctrl

    This does not seem to cause a problem but at the same time is wasting CPU and maybe causing heat issues ?

  2. beeblebrox

    beeblebrox Network Guru Member

    This is similar to the issues I'm having. Are you able to reliably use the connection? Can you view larger websites (if you can view any at all) or use other applications?

    I'm sure you've found out that killing that process takes the pptp connection with it.
  3. sir_lunatic

    sir_lunatic Network Guru Member

    Well the cpu is max'd out for two reasons.....

    1. its a small slow processor, its doin its best man.....it thinks it can, it thinks it can. You get the idear....


    2. pptp is busy compressing and encrypting and decrypting and uncompressing with every bit that comes it way. and pptp is chatty even when your not doing anything.

    So add these two together and I think you can see the answer. If it bugs ya, you can nice the pptp process.

    As far as the problem with not being able to view larger site, see my post at:

    Not sure about the dns problem though.......
  4. mjkidd

    mjkidd Network Guru Member

    Not sure about CPU being maxed for that reason - I used to run wifibox on a WRT54G V1.0 and leave VPN up for days - CPU did not max at all. Now I have GS c1.1 so more CPU available and it maxes out.

    Its just puzzling at the moment, does not seem to have any adverse effect and DD-WRT is far superior to wifibox (only reason i stuck with it was the pptp VPN)

    DNS is the real bugbear at the moment - again this worked fine with wifibox, hopefully I can get access to a 54G v1.0 next week running wifibox and compare. I'll post the outcome.
  5. sir_lunatic

    sir_lunatic Network Guru Member

    As far as the dns prob.....

    IF there was an editor available (ie. VI) you could edit /tmp/pptpd/options.conf and add the dns servers you want to use in the form of:

    ms-dns x.x.x.x
    ms-dns x.x.x.x

    and you could add WINS servers as well

    ms-wins x.x.x.x
    ms-wins x.x.x.x

    These values would get passed to your vpn client upon connect.

    Its how I do things here.............

    Ed Note: pre5 now has vi back in it........sorry for the sarcasm
  6. mjkidd

    mjkidd Network Guru Member

    No the problem is not that DNS details are not being passed - but that router passes its own IP as DNS server.

    nslookup on local (wired or wireless) machine to router or directly on router cli works fine, but from tunnel does not.

    I am using split tunnel so do not need linksys to do DNS (might be slightly usefull for resolving LAN client I guess) as I resolve locally (ie ISP). Problem is that XP tries local and linksys in parallel and sometimes get confused. Not sure why, just thinking while I type this that maybe the local DNS cache is getting a negative entry I will try disabling caching this and see what happens.

    As the DNS server seems to work fine I guess its an iptables issue - prob is I have not really got to grips with iptables yet.
  7. sir_lunatic

    sir_lunatic Network Guru Member

    Your correct that this is an iptables issue, hence this is why I dont use the linky address for dns resolution. The dns-masq on the linky is at best sub-par. For a home user it is more that ample, but for more advanced users it just doent cut it. So I personally decided not to use it.
  8. mjkidd

    mjkidd Network Guru Member

    Oh didnt realise that the DNS masq option was triggering the pptp to supply a DNS server.

    I'll try and turn this off and see how it behaves from the office next week.

    Sounds promissing
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