BT DSL’s Daily Disconnects

Argh! This is what happens every day to my DSL connection, at half past 12:

13 Mon Apr 10 12:26:53 2006 PP12 -WARN  SNMP TRAP 2: link down
14 Mon Apr 10 12:26:53 2006 PP12  INFO  ppp_ready: ch:8056167c, iface:80419f14
15 Mon Apr 10 12:26:53 2006 PP12 -WARN  SNMP TRAP 3: link up
26 Tue Apr 11 12:26:46 2006 PP12 -WARN  SNMP TRAP 2: link down
28 Tue Apr 11 12:26:48 2006 PP12  INFO  ppp_ready: ch:8056167c, iface:80419f14
29 Tue Apr 11 12:26:48 2006 PP12 -WARN  SNMP TRAP 3: link up
38 Wed Apr 12 12:26:56 2006 PP12 -WARN  SNMP TRAP 2: link down
40 Wed Apr 12 12:26:58 2006 PP12  INFO  ppp_ready: ch:8056167c, iface:80419f14
41 Wed Apr 12 12:26:58 2006 PP12 -WARN  SNMP TRAP 3: link up
50 Thu Apr 13 12:27:00 2006 PP12 -WARN  SNMP TRAP 2: link down
52 Thu Apr 13 12:27:03 2006 PP12  INFO  ppp_ready: ch:8056167c, iface:80419f14
53 Thu Apr 13 12:27:03 2006 PP12 -WARN  SNMP TRAP 3: link up

Worse than that, it will generally assign a different IP address to the connection when it reconnects! This buggers up any applications that rely on long-lived TCP connections, such as SSH shell logins, tunnels, remote-desktop sessions, and instant messaging; all get disconnected and have to be manually re-set up.

Initially, I thought this may have been a flaky connection. However, it appears not — check out those timestamps; that’s a scheduled, daily event. Also, there have been no other disconnections apart from those.

A discussion on the IIU mailing list revealed the reason — it seems BT Ireland have a policy of resetting their customers’ connections daily. That could be OK, if they came right back up with the same IP — TCP/IP is designed to cope with that, and generally does — but it does not do that. Instead the IP address is reassigned every single time.

This is turning out to be quite a nuisance. Working over the internet requires quite a few VPN connections, tunnels, and remote logins, and having to re-set those up, daily, is turning out to be a pain in the neck.

I’m casting around for hacks to get around this. Right now, I have an assortment of jiggery-pokery involving ssh, a shell script ‘while’ loop, and screen(1), but it’s messy and not working out too well. Ideally, I’d set up another VPN (via IPSec or CIPE), and set it up to reconnect on link failure, then route all other VPNs and remote logins out via that — but I don’t have spare routable IPs to do this with. Anyone got any good suggestions?

By the way, it’s worth noting that their FAQ fails to mention this, instead giving some incorrect information about my IP being ‘removed’ when my web browsing session ends:

Is it a fixed IP?

No, the product is set up with dynamic IP Addressing. This means that every time you open your browser you will be allocated a different IP address for the duration of that session. When the session ends the IP Address is removed.

That is incorrect — this has nothing to do with web browsing sessions.

To be honest, I’d prefer not to have to switch ISPs to get away from this brokenness — the rest of the service is quite nice, good pings, good throughput, no other disconnections or outages — but this is quite a problem for someone using BT Broadband for telecommuting purposes. :(

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  1. Posted April 13, 2006 at 15:14 | Permalink

    Ha, I’ve got the same problem with T-Online in Germany – the only solution I could come up with is to manually disconnect the network in the middle of the night (e.g. at 4:30AM) – the following, daily disconnects will then be at the same time and so they won’t disturb me while working by daylight; I’m rarely doing important things at this time of the night ;-)

  2. Posted April 13, 2006 at 15:58 | Permalink

    hi Eric —

    well, unfortunately even with a forced disconnect from my end, it still assigns a new IP address, for no good reason that I can see. annoying. :(

  3. Posted April 13, 2006 at 16:02 | Permalink

    Justin, That’s bad, I’ve not experienced anything like that with utv internet – I’m pretty sure my router generally stays connected at the same IP addressas as long as it’s powered up. (I think you can pay utv a fiver a month or something to allocate you a fixed IP). I know, extortion, and their caps might not be as high as you’d want… You’d be advised to find out how long you’d be forced off line while you get disconnected/reconnected if you do decide to switch, they all have to mediate with eircom at the back end and you can suspect what happens there…

  4. Posted April 13, 2006 at 16:24 | Permalink

    I just got esat bb last week and I’m noticing this immediately. I had loads of connections to work around lunch time (X, ssh, …) which just stopped working even though I could still ping outside. On closer investigation I noticed the IP totally changed from 213.202.128/18 to 194.125.64/18


  5. adam
    Posted April 13, 2006 at 16:37 | Permalink

    As I mentioned on IIU, consider yourself lucky! It’s happening at least twice a day for me, and more often 3 or 4 times a day. One of the disconnects is on a schedule though, like yourself, sometime around 4pm. What a time to do it like!

    I stayed with them up until now because although their administration resembles the work of mentally-challenged chimpanzees, it’s technically been a good service. If the technical reliability/usability isn’t there though, there’s no reason to stay with them.

    To anyone considering the same course of action: Do it in writing. By registered mail. Twice. Seriously.

  6. Posted April 13, 2006 at 17:05 | Permalink

    Have you considered using an IPv6 tunnel, like that available from SixXS? I’m currently on a static IP (or at least, DHCP has always given me back the same address in the recent past), so I haven’t actually tested that connections will continue to work, but it’d be worth trying out. aiccu should send notification pings, which will cause IPv6 packets to be sent to the new IP address. All you need is an IPv6-enabled server out there, I can think of one such off the top of my head :-)

  7. David Malone
    Posted April 13, 2006 at 18:31 | Permalink

    My Eircom DSL seems to keep a fixed IP for long periods of time, which is good ‘cos I use 6to4 for IPv6 connectivity and for this the IPv6 addresses depend on the IPv4 addresses. As Gary suggests, if you use a configured tunnel and move the IPv4 end point whenever the IP address changes you shouldn’t notice.

  8. Posted April 13, 2006 at 18:36 | Permalink

    Gary —

    you may be onto something there. hmm, I’ll give it a go. About time I mucked about with IPv6 anyway ;)

    Can I route back out onto the IPv4 internet from an IPv6 tunnel? ie. go

    home\_network -> IPv6\_tunnel -> endpoint -> IPv4 sites


  9. Posted April 13, 2006 at 20:02 | Permalink

    It could be something simple like they need to drop the ppp session so as to get a Radius Stop message to clean up the radius accounting.

  10. Posted April 13, 2006 at 20:17 | Permalink

    hi Colin —

    that’s logical — although would it really imply that they’d have to lose the DHCP lease, too? As I said, dropping the connection for a second or two isn’t the problem — it’s the IP address changing that screws up existing TCP sessions.

  11. Posted April 15, 2006 at 00:27 | Permalink

    This is getting unusable. My IP address changed again at 22:45 so it seems to be pretty random. Also changing the address breaks firewall rules that have been setup on another system to allow me to ssh in. Functionally this is actually worse than dialup as at least there I was guaranteed an IP for the session.

    So it’s only useful for short lived stateless transactions. I.E. web browsing. (I guess even certain (authenticated) web services wouldn’t even work under these conditions).

    Any sort of telecommuting is problematic because of the requirement for long lived connections.

    In the blurb on the website they mention services like “streaming radio broadcasts”, “online gaming”, and video conferencing. How are those services affected by this?


  12. Posted April 15, 2006 at 21:41 | Permalink

    yeah, I haven’t come up with a solution either; the IPv6 suggestion is quite a lot of work, and I’m not sure if it’ll really help given that many of the nodes I want to contact are still IPv4 only, and AFAICS there’s no applicable v6-to-v4 tunnel for SSH traffic.

    I’m also running into the major hassle of having to keep getting our IT staff to poke massive swathes in the firewall — ESAT are assigning out of huge ranges, not even just a /24. The dialup pools seem to include:

   - #
   - #

    there’s a 19x range, too, but I haven’t figured out its extents yet.

    This is a major PITA.

  13. Posted April 17, 2006 at 20:27 | Permalink

    Hey Justin, welcome back in Europe :)

    As Erik said, these reconnects are pretty common, at least over here in Germany. Its not only T-Offline, almost all the other big ISPs have that IP-change, too. Why? Because they also sell “business” tariffs where you pay for your static IP. (Erik: try they are a T-DSL reseller and offer semi-static IPs for a good price and good service.) Pretty annoying if you have to set up IPsec tunnels without NAT-T on the endpoint :-/

    As most of my long-living connections are SSH ones, too, I also do the cron reconnect trick (actually, I use a cheap hardware power timer to reboot the router every 24h because m0n0wall doesn’t have such a feature). For the port forwards I need I use this simple script in a cron job to connect back from the server to the machines which need it. For my outgoing connections I use ssh-agent most the time to avoid being asked for the password all the time.

  14. Posted April 18, 2006 at 15:13 | Permalink

    hey Malte — thanks!

    yeah, ssh hacks are turning out to be the order of the day. I was hoping I could find something more resilient, but no luck so far…

  15. Posted April 24, 2006 at 17:12 | Permalink

    Hi Justin, there’s a simple solution & a really complicated one ;) An IPv6 multi-homing like effect can be achieved using IPv4 and mobile IP (RFC3344). You can hack together an acceptable solution using IP forwarding if you configure a Home Agent to handle IP forwarding & buffering. You could then introduce further levels of indirection through transport layer SSH port forwarding to a box that can handle mobile IPv4 forwarding. From a purely academic standpoint this would be an interesting solution and resilient depending on how it’s configured.. I think is do-able through the vtun package on debian, excuse the bias…

    Also, when surfing the web over native IP6 boxes we use an acceptable tunnelling solution through SixXS @

  16. Posted April 28, 2006 at 14:17 | Permalink

    so — an update.

    I still have no useful workaround. I’ve investigated IPv6 and IPSec VPNs, but right now that’s stalled due to a lack of routable IPs or the skill and time to set up a combination of NAT and normal IP endpoints on our server (I can’t just NAT every port, since there’s a lot of normal services there). It really is turning out to be a very tricky thing to work around. :(

  17. Posted April 28, 2006 at 14:18 | Permalink

    oh, I should point out that IPv6 alone is not a solution; most of the sites I need to maintain sessions on, are v4 only.

  18. Vincent
    Posted October 2, 2006 at 15:42 | Permalink


    I’m a recent subscriber to BT Ireland’s broadband service and experiencing great difficulty using it because of this IP policy. Did you work out any solution to this problem?


  19. Posted October 2, 2006 at 15:59 | Permalink

    Vincent — nope, no luck. Magnet rang me recently, saying that they’ve now got unbundled access to my exchange — I may switch, given that…

  20. Posted February 21, 2007 at 18:12 | Permalink

    Hi Justin

    Any update on this. Just discovered the problem myself, after hounding the IT department for months on their new SSL VPN; turns out its BT’s disconnects.

    Do you think it would be worth looking at setting up a proxy server on the web somewhere with a static IP and then routing through it; so at least the VPN server will see the see the same IP; i.e. would IPSEC work thru a proxy? Jeremy

  21. Posted February 21, 2007 at 20:15 | Permalink

    Jeremy — it’s still an issue; no updates I know of.

    Well, BT plan to stop offering broadband to residential customers apparently, I guess that’s quite an update! :(

    also, IPSec is quite allergic to proxies or any other kind of “man-in-the-middle”, by design, I’m afraid. what I do for my VPN (over ssh) is to simply restart the connections whenever they fall over, using external scripting. It’s very messy and doesn’t help for all use cases.

  22. Posted February 22, 2007 at 15:26 | Permalink

    Hi Justin

    Just had a very helpful tech support guy on from BT. Told me that the Residential DSL should only be re-setting once every 24 hours.

    Got me to log into the modem (Zyxel), go into the Wizard set-up, and change the connection from “Connect on demand” to “nailed up connection”. – and then apply. Also, told me to restart the modem sometime that will make it convenient for the 24 hour IP change – i.e. restart it at 6am, and then it’ll change IP every day at 6am. Hopefully this will sort it – I’m running an IP logger, (Logging my IP every 5 minutes) so will let you know how it goes.

  23. Posted March 2, 2007 at 13:31 | Permalink

    good tip Jeremy! I’ve followed up with that in this post:

  24. john
    Posted February 12, 2008 at 19:51 | Permalink

    Changed three lines to bt & they lost one. the cost was about 25% dearer than eircom for calls. changed back to eircom. eircom sucks but bt is worse. both company’s customer services are incompetentent.:-).

  25. Posted February 29, 2008 at 16:32 | Permalink


  26. Posted June 18, 2008 at 13:43 | Permalink

    ARGH, i have the same problem with bt. Every day at 13:00 my ip address changes, im currently e-mailing technical support, and they’re just after throwing their terms and conditions at me.

    its so frustrating! i have a vpn tunnel set up with a friend so we can share storage servers and that. I also run a irc server and a gaming server all of these things drop out. Along with skype, msn and ssh sessions i have open, its so annoying. But what can i say? iv agreed to it in the terms and conditions :(

  27. Sean O\'Connor
    Posted March 24, 2009 at 12:08 | Permalink

    Have any of you stopped to think that the reason BT resets your IP every day is to recycle the addresses?

    IPs using IPv4 are beginning to become like gold dust and they’re running out very quickly. Any ISP who DOESN’T follow suit for residential customers is just being careless.

    If you’re losing your VPN connection due to firewall restrictions, you really should have a business account. Another workaround though, would be to set up a dynamic DNS and get the techies to allow the domain, rather than an IP

    Still, what residential customer actually NEEDS to keep their IP?

    Also, a quick note: if you turn off the modem at a time when you never use your connection (ie 5am) and turn it back on, it will reset regularly at that time every night.

  28. Posted March 24, 2009 at 12:51 | Permalink

    @Sean O’Connor — thanks for the comment.

    ‘If you’re losing your VPN connection due to firewall restrictions, you really should have a business account.’

    Regarding the idea of telecommuters having business accounts — good luck with that. Given the choice between forking out twice the price for a static-IP-boasting business account vs switching to another ISP for the same amount of money, I think they’d probably pick the latter.

    But if these plans: offer static IPs, that’s cool. Do they? Anyone know?

    ‘Another workaround though, would be to set up a dynamic DNS and get the techies to allow the domain, rather than an IP’

    I don’t know of a firewall-restricted VPN that allows ingress by DNS hostname. do you?

    ‘Also, a quick note: if you turn off the modem at a time when you never use your connection (ie 5am) and turn it back on, it will reset regularly at that time every night.’

    Yes. and all your VPN/SSH connections will have reset when you start work in the morning. ;)

    (for what it’s worth, I switched to Magnet and am loving it.)

  29. Posted January 9, 2011 at 01:22 | Permalink

    Update: is a particularly useful thread about this, which still seems to be going on.

    I switched to Magnet and eventually NTL; neither do this kind of stupid trick.

    (BTW a little bird told me that BT/Esat/Vodafone do this purely to work around a bug in their billing system; each line needs to see some kind of “activity” once every 24 hours for billing to work correctly. If so, this bug has been unfixed for several years. Very encouraging w.r.t. the build quality of the rest of their service…)