5 ms·

Launch ´mtr google.com’ on one of your devices (preferably connected via Ethernet to your router) a few minutes before the cut off, and watch what happens when

by xgbi 6y ago

Launch ´mtr google.com’ on one of your devices (preferably connected via Ethernet to your router) a few minutes before the cut off, and watch what happens when the cut occurs. It will show you exactly which equipment on the route starts dropping. Although I suspect your ISP has a 24h lease and your modem renegociates at 3:40 everyday

KronisLV 6y ago
Here's a summary from the man pages of mtr, for those who are not familiar with the tool but maybe are reading HN on their phones so can't check it out: mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool. As mtr starts, it investigates the network connection between the host mtr runs on and HOSTNAME by sending packets with purposely low TTLs. It continues to send packets with low TTL, noting the response time of the intervening routers. This allows mtr to print the response percentage and response times of the internet route to HOSTNAME. A sudden increase in packet loss or response time is often an indication of a bad (or simply overloaded) link. The results are usually reported as round-trip-response times in milliseconds and the percentage of packetloss. This actually makes me wonder about whether there's a command that'll let me see short summaries of what every file under /usr/bin is, in the form of a list. Definitely wasn't aware of mtr as an average web developer up until now.
- lambdaba 6y ago
  apropos -s 1 . will list a short description from the manpages (might have to run mandb first)
ksec 6y ago
On the subject of Lease Time. My router is currently showing a lease time of 3 Min. I think most router tends to renew their IP at 50% of ISP's lease time ( in this case 6 min ) What are the purpose of these ridiculously low lease time? I remember in the old days they tend to go for 48 hours if not longer.
- igetspam 6y ago
  To get you to pay more money for a static IP.
  - ksec 6y ago
    Seems Reasonable, but I though most ISP dont want Home users to be using Static IPs. And apology for asking an off topic question. I guess that is what the downvotes are coming from.
    - wernercd 6y ago
      There's a limited number of IPs so most homes CANT use static... we already don't have enough IPs for the mountains of devices. But the other part is money... why give something away for free when you can make it a "feature" to pay for? Tons of other reasons in various articles... https://www.online-tech-tips.com/computer-tips/ott-explains-why-isps-assign-dynamic-vs-static-ip-addresses/ https://www.online-tech-tips.com/computer-tips/ott-explains-... https://superuser.com/questions/590391/why-do-isps-change-your-ip-address https://superuser.com/questions/590391/why-do-isps-change-yo...
      - eppp 6y ago
        I work at an ISP and setup both static and dhcp services. Statics take far more work and management than dhcp, ignoring the scarcity problem. We make you pay more because you are requesting something that requires both documentation and management on a home connection. Id be glad to give them away for free but it is all downside for us and over 99% of residential customers dont want one to start with. I think we have 3 residential customers out of 1500 that have statics.
        wernercd 6y ago
        After having read some of the articles on it (including the two listed), the mechanics are something that are probably a lot more intensive to manage than I figured initially. Changing DHCP is a couple changes and then... wait. Changing hard coded paths and all that... I'm actually glad I don't deal with that stuff on a day to day... but I like learning about it.
wjnc 6y ago
So then the trick is to forgo internet by disconnecting power from a few minutes before that time to the middle of the night and get power back? I do feel for the ISP's with this setup because the right thing to do would be to write in the installation manual: "Only install in the deep of night".
- milankragujevic 6y ago
  Well they could 1) renew the IP before it expires or 2) reboot the modem remotely at 3:30am for example.
  - hsbauauvhabzb 6y ago
    Or assign a lease that expires at 0330 instead of a lease that expires in 24 hours. But I’ve not experienced similar in 20 years of dynamic ips.
- rantwasp 6y ago
  it depends. depending on the dhcp implementation on the server side you may have the same problem (ie while you get a new lease it may expire at the same time). unlikely but I’ve seen some stuff when it comes to dhcp
throw0101a 6y ago
Actually it seems that it is not renegotiating everyday: it is expiring and re-requesting. The way DHCP 'should' work is that when a client is part-way through the lease it should try to renew the IP it already has: * https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol#Reliability https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Pro... * https://tools.ietf.org/html/rfc2131#section-4.4.5 https://tools.ietf.org/html/rfc2131#section-4.4.5 This allows the client to (hopefully) keep extending the IP it has so that a re-IP does not cause current connections to drop. If the modem is not doing this (can the OP log into it in someway to see logs?), then it is acting as a 'non-ideal' DHCP client. Until this is sorted out, try rebooting the modem an an 'odd' hour that will not disrupt you during the day. This is no guarantee though: the DHCP server may remember the old/current DHCP lease and simply re-issue it with the same expiration time. I'm on DSL/PPPoE, so this may not apply, but: my Asus router has a setting that allows it to automatically reboot. I do this at ~04h00 to get a new IP every day so help with privacy concerns. I generally surf with cookies disabled, so these two things help with the low-hanging fruit of simple tracking techniques. (My DSL modem is bridged.)
- dayjah 6y ago
  I had this exact issue in 2008 in SF on Comcast Business. The lease would be dropped and renegotiated every few hours, we could notice it because our SSH tunnels would get torn down. What was annoying was that the business plan had a static IP associated with it, presumably managed by their DHCP setup. It took weeks to convince Comcast the issue wasn’t in our building, and moments for them to fix once they “got it”.
  - patneedham 6y ago
    What piece of evidence or logs finally convinced Comcast that the issue was on their side?
    - dayjah 6y ago
      Honestly my memory is not that good! I remember a few tech visits as they replaced modems, etc, and I eventually got to some “3rd level support person” that said something akin to “oh, that issue again”.
runjake 6y ago
This is the correct answer. Although typically leases will attempt a renewal halfway through the lease time, so it would be a 48 hour lease. As OP said, mtr will tell you where in the line it’s happening.

by xgbi 6y ago

KronisLV 6y ago

Here's a summary from the man pages of mtr, for those who are not familiar with the tool but maybe are reading HN on their phones so can't check it out: mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool. As mtr starts, it investigates the network connection between the host mtr runs on and HOSTNAME by sending packets with purposely low TTLs. It continues to send packets with low TTL, noting the response time of the intervening routers. This allows mtr to print the response percentage and response times of the internet route to HOSTNAME. A sudden increase in packet loss or response time is often an indication of a bad (or simply overloaded) link. The results are usually reported as round-trip-response times in milliseconds and the percentage of packetloss. This actually makes me wonder about whether there's a command that'll let me see short summaries of what every file under /usr/bin is, in the form of a list. Definitely wasn't aware of mtr as an average web developer up until now.

lambdaba 6y ago
apropos -s 1 . will list a short description from the manpages (might have to run mandb first)

ksec 6y ago

On the subject of Lease Time. My router is currently showing a lease time of 3 Min. I think most router tends to renew their IP at 50% of ISP's lease time ( in this case 6 min ) What are the purpose of these ridiculously low lease time? I remember in the old days they tend to go for 48 hours if not longer.

igetspam 6y ago
To get you to pay more money for a static IP.
- ksec 6y ago
  Seems Reasonable, but I though most ISP dont want Home users to be using Static IPs. And apology for asking an off topic question. I guess that is what the downvotes are coming from.
  - wernercd 6y ago
    There's a limited number of IPs so most homes CANT use static... we already don't have enough IPs for the mountains of devices. But the other part is money... why give something away for free when you can make it a "feature" to pay for? Tons of other reasons in various articles... https://www.online-tech-tips.com/computer-tips/ott-explains-why-isps-assign-dynamic-vs-static-ip-addresses/ https://www.online-tech-tips.com/computer-tips/ott-explains-... https://superuser.com/questions/590391/why-do-isps-change-your-ip-address https://superuser.com/questions/590391/why-do-isps-change-yo...
    - eppp 6y ago
      I work at an ISP and setup both static and dhcp services. Statics take far more work and management than dhcp, ignoring the scarcity problem. We make you pay more because you are requesting something that requires both documentation and management on a home connection. Id be glad to give them away for free but it is all downside for us and over 99% of residential customers dont want one to start with. I think we have 3 residential customers out of 1500 that have statics.
      - wernercd 6y ago
        After having read some of the articles on it (including the two listed), the mechanics are something that are probably a lot more intensive to manage than I figured initially. Changing DHCP is a couple changes and then... wait. Changing hard coded paths and all that... I'm actually glad I don't deal with that stuff on a day to day... but I like learning about it.

wjnc 6y ago

So then the trick is to forgo internet by disconnecting power from a few minutes before that time to the middle of the night and get power back? I do feel for the ISP's with this setup because the right thing to do would be to write in the installation manual: "Only install in the deep of night".

milankragujevic 6y ago
Well they could 1) renew the IP before it expires or 2) reboot the modem remotely at 3:30am for example.
- hsbauauvhabzb 6y ago
  Or assign a lease that expires at 0330 instead of a lease that expires in 24 hours. But I’ve not experienced similar in 20 years of dynamic ips.
rantwasp 6y ago
it depends. depending on the dhcp implementation on the server side you may have the same problem (ie while you get a new lease it may expire at the same time). unlikely but I’ve seen some stuff when it comes to dhcp

throw0101a 6y ago

Actually it seems that it is not renegotiating everyday: it is expiring and re-requesting. The way DHCP 'should' work is that when a client is part-way through the lease it should try to renew the IP it already has: * https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol#Reliability https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Pro... * https://tools.ietf.org/html/rfc2131#section-4.4.5 https://tools.ietf.org/html/rfc2131#section-4.4.5 This allows the client to (hopefully) keep extending the IP it has so that a re-IP does not cause current connections to drop. If the modem is not doing this (can the OP log into it in someway to see logs?), then it is acting as a 'non-ideal' DHCP client. Until this is sorted out, try rebooting the modem an an 'odd' hour that will not disrupt you during the day. This is no guarantee though: the DHCP server may remember the old/current DHCP lease and simply re-issue it with the same expiration time. I'm on DSL/PPPoE, so this may not apply, but: my Asus router has a setting that allows it to automatically reboot. I do this at ~04h00 to get a new IP every day so help with privacy concerns. I generally surf with cookies disabled, so these two things help with the low-hanging fruit of simple tracking techniques. (My DSL modem is bridged.)

dayjah 6y ago
I had this exact issue in 2008 in SF on Comcast Business. The lease would be dropped and renegotiated every few hours, we could notice it because our SSH tunnels would get torn down. What was annoying was that the business plan had a static IP associated with it, presumably managed by their DHCP setup. It took weeks to convince Comcast the issue wasn’t in our building, and moments for them to fix once they “got it”.
- patneedham 6y ago
  What piece of evidence or logs finally convinced Comcast that the issue was on their side?
  - dayjah 6y ago
    Honestly my memory is not that good! I remember a few tech visits as they replaced modems, etc, and I eventually got to some “3rd level support person” that said something akin to “oh, that issue again”.

runjake 6y ago

This is the correct answer. Although typically leases will attempt a renewal halfway through the lease time, so it would be a 48 hour lease. As OP said, mtr will tell you where in the line it’s happening.