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Groups > comp.os.linux.networking > #4704 > unrolled thread
| Started by | Charlie Gibbs <cgibbs@kltpzyxm.invalid> |
|---|---|
| First post | 2020-11-15 04:31 +0000 |
| Last post | 2020-11-17 00:18 +0000 |
| Articles | 7 — 3 participants |
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Long delay when starting slrnpull Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-11-15 04:31 +0000
Re: Long delay when starting slrnpull Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-11-15 08:00 +0000
Re: Long delay when starting slrnpull Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-11-15 18:03 +0000
Re: Long delay when starting slrnpull Richard Kettlewell <invalid@invalid.invalid> - 2020-11-15 11:49 +0000
Re: Long delay when starting slrnpull Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-11-15 18:03 +0000
Re: Long delay when starting slrnpull Richard Kettlewell <invalid@invalid.invalid> - 2020-11-16 17:27 +0000
Re: Long delay when starting slrnpull Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-11-17 00:18 +0000
| From | Charlie Gibbs <cgibbs@kltpzyxm.invalid> |
|---|---|
| Date | 2020-11-15 04:31 +0000 |
| Subject | Long delay when starting slrnpull |
| Message-ID | <roqavg12kqs@news3.newsguy.com> |
Every time I fire up slrnpull on my laptop when attached to my home network, it sits for 20 to 30 seconds before checking the newsgroups it's configured to download. The actual checks and downloads run at full speed. This happens whether I'm using Wi-Fi or have an Ethernet cable plugged in, and only happens on my home network; when I take the laptop to the office it pulls news immediately. I suspect that there might be some sort of DNS problem, but I'm not sure. Most other Internet functions work well, and speedtest.net indicates 88Mbps for downloads and almost as fast for uploads. Any idea where I should look? Below is the first part of a tcpdump, trimmed just after the point where everything woke up. (Debian Buster, slrnpull version 1.0.3) 13:41:55.720186 IP cjglap2.59960 > _gateway.domain: 15913+ A? news.newsguy.com. (34) 13:41:55.720217 IP cjglap2.59960 > _gateway.domain: 42553+ AAAA? news.newsguy.com. (34) 13:41:56.161877 IP cjglap2.47905 > _gateway.domain: 8298+ PTR? 1.0.168.192.in-addr.arpa. (42) 13:42:00.724932 IP cjglap2.52392 > 75.153.171.122.domain: 15913+ A? news.newsguy.com. (34) 13:42:00.724964 IP cjglap2.52392 > 75.153.171.122.domain: 42553+ AAAA? news.newsguy.com. (34) 13:42:00.849895 ARP, Request who-has _gateway tell cjglap2, length 28 13:42:00.867532 IP 75.153.171.122.domain > cjglap2.52392: 15913 8/0/0 A 74.209.136.82, A 74.209.136.88, A 74.209.136.94, A 74.209.136.95, A 74.209.136.89, A 74.209.136.92, A 74.209.136.90, A 74.209.136.91 (162) 13:42:00.867569 IP 75.153.171.122.domain > cjglap2.52392: 42553 0/1/0 (85) 13:42:00.867582 ARP, Reply _gateway is-at 10:78:5b:c8:34:d0 (oui Unknown), length 46 13:42:00.868016 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [S], seq 3627346142, win 64240, options [mss 1460,sackOK,TS val 959274309 ecr 0,nop,wscale 7], length 0 13:42:00.974107 IP news.newsguy.com.nntp > cjglap2.33958: Flags [S.], seq 1176698976, ack 3627346143, win 65535, options [mss 1460,nop,wscale 6,sackOK,TS val 2806053013 ecr 959274309], length 0 13:42:00.974160 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [.], ack 1, win 502, options [nop,nop,TS val 959274415 ecr 2806053013], length 0 13:42:01.166389 IP cjglap2.41331 > 75.153.171.122.domain: 8298+ PTR? 1.0.168.192.in-addr.arpa. (42) 13:42:01.192641 IP 75.153.171.122.domain > cjglap2.41331: 8298 NXDomain* 0/1/0 (101) 13:42:01.208844 IP cjglap2.55728 > _gateway.domain: 16832+ PTR? 46.0.168.192.in-addr.arpa. (43) 13:42:01.234545 IP _gateway.domain > cjglap2.55728: 16832 NXDomain* 0/1/0 (102) 13:42:01.281870 IP cjglap2.60452 > _gateway.domain: 20526+ PTR? 122.171.153.75.in-addr.arpa. (45) 13:42:01.306107 IP _gateway.domain > cjglap2.60452: 20526 NXDomain 0/1/0 (105) 13:42:01.321593 IP cjglap2.37199 > _gateway.domain: 60411+ PTR? 82.136.209.74.in-addr.arpa. (44) 13:42:01.672966 IP _gateway.domain > cjglap2.37199: 60411 1/0/0 PTR news.newsguy.com. (74) 13:42:05.879967 ARP, Request who-has cjglap2 tell _gateway, length 46 13:42:05.879996 ARP, Reply cjglap2 is-at 18:3d:a2:a6:56:14 (oui Unknown), length 28 13:42:05.897566 IP _gateway.37186 > cjglap2.netbios-ns: UDP, length 50 13:42:05.897612 IP cjglap2 > _gateway: ICMP cjglap2 udp port netbios-ns unreachable, length 86 13:42:28.391109 IP news.newsguy.com.nntp > cjglap2.33958: Flags [P.], seq 1:44, ack 1, win 1040, options [nop,nop,TS val 2806080439 ecr 959274415], length 43 13:42:28.391155 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [.], ack 44, win 502, options [nop,nop,TS val 959301832 ecr 2806080439], length 0 13:42:28.391243 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [P.], seq 1:14, ack 44, win 502, options [nop,nop,TS val 959301832 ecr 2806080439], length 13 13:42:28.487940 IP news.newsguy.com.nntp > cjglap2.33958: Flags [P.], seq 44:81, ack 14, win 1040, options [nop,nop,TS val 2806080535 ecr 959301832], length 37 13:42:28.488168 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [P.], seq 14:36, ack 81, win 502, options [nop,nop,TS val 959301929 ecr 2806080535], length 22 -- /~\ Charlie Gibbs | "Some of you may die, \ / <cgibbs@kltpzyxm.invalid> | but it's sacrifice X I'm really at ac.dekanfrus | I'm willing to make." / \ if you read it the right way. | -- Lord Farquaad (Shrek)
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| From | Jorgen Grahn <grahn+nntp@snipabacken.se> |
|---|---|
| Date | 2020-11-15 08:00 +0000 |
| Message-ID | <slrnrr1o07.2ptb.grahn+nntp@frailea.sa.invalid> |
| In reply to | #4704 |
On Sun, 2020-11-15, Charlie Gibbs wrote: > Every time I fire up slrnpull on my laptop when attached to my home > network, it sits for 20 to 30 seconds before checking the newsgroups > it's configured to download. The actual checks and downloads run at > full speed. This happens whether I'm using Wi-Fi or have an Ethernet > cable plugged in, and only happens on my home network; when I take the > laptop to the office it pulls news immediately. > > I suspect that there might be some sort of DNS problem, but I'm > not sure. Most other Internet functions work well, and speedtest.net > indicates 88Mbps for downloads and almost as fast for uploads. > > Any idea where I should look? Below is the first part of a tcpdump, > trimmed just after the point where everything woke up. Seems to me you can ignore your DNS queries, and that you can trim the problem down to: > 13:42:00.868016 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [S], seq 3627346142, win 64240, options [mss 1460,sackOK,TS val 959274309 ecr 0,nop,wscale 7], length 0 > 13:42:00.974107 IP news.newsguy.com.nntp > cjglap2.33958: Flags [S.], seq 1176698976, ack 3627346143, win 65535, options [mss 1460,nop,wscale 6,sackOK,TS val 2806053013 ecr 959274309], length 0 > 13:42:00.974160 IP cjglap2.33958 > news.newsguy.com.nntp: Flags [.], ack 1, win 502, options [nop,nop,TS val 959274415 ecr 2806053013], length 0 Now you have a TCP connection ... > 13:42:28.391109 IP news.newsguy.com.nntp > cjglap2.33958: Flags [P.], seq 1:44, ack 1, win 1040, options [nop,nop,TS val 2806080439 ecr 959274415], length 43 ... but then it took 28 seconds for the NNTP server to send something on it. It /should/ send a welcome message like "200 wombatvax news server ready - posting ok" -- the length of 43 bytes roughly matches that. Unless your gateway drops the first packets from mewsguy, forcing it to retransmit, it's actually newsguy causing the delay. Perhaps newsguy does something else first, like a reverse DNS lookup on your IP, and /that/ is what slows down? Then you'd see the exact same delay every time -- the time before newsguy gives up on the DNS lookup. You could use online reverse DNS lookup services on your various IP addresses, to see if one is broken. /Jorgen -- // Jorgen Grahn <grahn@ Oo o. . . \X/ snipabacken.se> O o .
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| From | Charlie Gibbs <cgibbs@kltpzyxm.invalid> |
|---|---|
| Date | 2020-11-15 18:03 +0000 |
| Message-ID | <rorqia1nln@news3.newsguy.com> |
| In reply to | #4705 |
On 2020-11-15, Jorgen Grahn <grahn+nntp@snipabacken.se> wrote: > On Sun, 2020-11-15, Charlie Gibbs wrote: > >> 13:42:28.391109 IP news.newsguy.com.nntp > cjglap2.33958: Flags [P.], seq 1:44, ack 1, win 1040, options [nop,nop,TS val 2806080439 ecr 959274415], length 43 > > ... but then it took 28 seconds for the NNTP server to send something > on it. It /should/ send a welcome message like "200 wombatvax news > server ready - posting ok" -- the length of 43 bytes roughly matches > that. > > Unless your gateway drops the first packets from mewsguy, forcing it > to retransmit, it's actually newsguy causing the delay. I suspect there's something wrong with my gateway. I always get the delay at home, but I never get it at the office. I'll try the same experiment when I get to the office on Tuesday. > Perhaps newsguy does something else first, like a reverse DNS lookup > on your IP, and /that/ is what slows down? Then you'd see the exact > same delay every time -- the time before newsguy gives up on the DNS > lookup. > > You could use online reverse DNS lookup services on your various IP > addresses, to see if one is broken. Thanks for the hints, I'll continue puttering. I'm wondering whether this also has something to do with the way my wife's Macbook sometimes hangs while downloading web pages... -- /~\ Charlie Gibbs | "Some of you may die, \ / <cgibbs@kltpzyxm.invalid> | but it's sacrifice X I'm really at ac.dekanfrus | I'm willing to make." / \ if you read it the right way. | -- Lord Farquaad (Shrek)
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| From | Richard Kettlewell <invalid@invalid.invalid> |
|---|---|
| Date | 2020-11-15 11:49 +0000 |
| Message-ID | <87ima6g7rg.fsf@LkoBDZeT.terraraq.uk> |
| In reply to | #4704 |
Charlie Gibbs <cgibbs@kltpzyxm.invalid> writes: > 13:41:55.720186 IP cjglap2.59960 > _gateway.domain: 15913+ A? > news.newsguy.com. (34) > 13:41:55.720217 IP cjglap2.59960 > _gateway.domain: 42553+ AAAA? > news.newsguy.com. (34) > 13:41:56.161877 IP cjglap2.47905 > _gateway.domain: 8298+ PTR? > 1.0.168.192.in-addr.arpa. (42) > 13:42:00.724932 IP cjglap2.52392 > 75.153.171.122.domain: 15913+ A? > news.newsguy.com. (34) Jorgen has explained most of the delay but you also have 4s delay here waiting for a DNS response from _gateway, whatever that is. (In general I suggest using the -n flag to tcpdump so that it doesn’t do its own DNS lookups.) -- https://www.greenend.org.uk/rjk/
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| From | Charlie Gibbs <cgibbs@kltpzyxm.invalid> |
|---|---|
| Date | 2020-11-15 18:03 +0000 |
| Message-ID | <rorqic3nln@news3.newsguy.com> |
| In reply to | #4706 |
On 2020-11-15, Richard Kettlewell <invalid@invalid.invalid> wrote: > Charlie Gibbs <cgibbs@kltpzyxm.invalid> writes: > >> 13:41:55.720186 IP cjglap2.59960 > _gateway.domain: 15913+ A? >> news.newsguy.com. (34) >> 13:41:55.720217 IP cjglap2.59960 > _gateway.domain: 42553+ AAAA? >> news.newsguy.com. (34) >> 13:41:56.161877 IP cjglap2.47905 > _gateway.domain: 8298+ PTR? >> 1.0.168.192.in-addr.arpa. (42) >> 13:42:00.724932 IP cjglap2.52392 > 75.153.171.122.domain: 15913+ A? >> news.newsguy.com. (34) > > Jorgen has explained most of the delay but you also have 4s delay here > waiting for a DNS response from _gateway, whatever that is. > > (In general I suggest using the -n flag to tcpdump so that it doesn’t do > its own DNS lookups.) I'll try that. I suspect that something isn't set up properly in my gateway. Just what do those A?, AAAA?, and PTR? flags mean? -- /~\ Charlie Gibbs | "Some of you may die, \ / <cgibbs@kltpzyxm.invalid> | but it's sacrifice X I'm really at ac.dekanfrus | I'm willing to make." / \ if you read it the right way. | -- Lord Farquaad (Shrek)
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| From | Richard Kettlewell <invalid@invalid.invalid> |
|---|---|
| Date | 2020-11-16 17:27 +0000 |
| Message-ID | <87a6vhfc05.fsf@LkoBDZeT.terraraq.uk> |
| In reply to | #4708 |
Charlie Gibbs <cgibbs@kltpzyxm.invalid> writes: > On 2020-11-15, Richard Kettlewell <invalid@invalid.invalid> wrote: >> Charlie Gibbs <cgibbs@kltpzyxm.invalid> writes: >> >>> 13:41:55.720186 IP cjglap2.59960 > _gateway.domain: 15913+ A? >>> news.newsguy.com. (34) >>> 13:41:55.720217 IP cjglap2.59960 > _gateway.domain: 42553+ AAAA? >>> news.newsguy.com. (34) >>> 13:41:56.161877 IP cjglap2.47905 > _gateway.domain: 8298+ PTR? >>> 1.0.168.192.in-addr.arpa. (42) >>> 13:42:00.724932 IP cjglap2.52392 > 75.153.171.122.domain: 15913+ A? >>> news.newsguy.com. (34) >> >> Jorgen has explained most of the delay but you also have 4s delay here >> waiting for a DNS response from _gateway, whatever that is. >> >> (In general I suggest using the -n flag to tcpdump so that it doesn’t do >> its own DNS lookups.) > > I'll try that. I suspect that something isn't set up properly > in my gateway. Just what do those A?, AAAA?, and PTR? flags mean? A? news.newsguy.com: A request for the IPv4 addresses for news.newsguy.com. AAAA? news.newsguy.com: A request for the IPv6 addresses for news.newsguy.com. PTR? 1.0.168.192.in-addr.arpa: A requeswt for the names corresponding to 192.168.0.1. -- https://www.greenend.org.uk/rjk/
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| From | Charlie Gibbs <cgibbs@kltpzyxm.invalid> |
|---|---|
| Date | 2020-11-17 00:18 +0000 |
| Message-ID | <rov4su012f5@news2.newsguy.com> |
| In reply to | #4709 |
On 2020-11-16, Richard Kettlewell <invalid@invalid.invalid> wrote: > Charlie Gibbs <cgibbs@kltpzyxm.invalid> writes: > >> On 2020-11-15, Richard Kettlewell <invalid@invalid.invalid> wrote: >> >>> Charlie Gibbs <cgibbs@kltpzyxm.invalid> writes: >>> >>>> 13:41:55.720186 IP cjglap2.59960 > _gateway.domain: 15913+ A? >>>> news.newsguy.com. (34) >>>> 13:41:55.720217 IP cjglap2.59960 > _gateway.domain: 42553+ AAAA? >>>> news.newsguy.com. (34) >>>> 13:41:56.161877 IP cjglap2.47905 > _gateway.domain: 8298+ PTR? >>>> 1.0.168.192.in-addr.arpa. (42) >>>> 13:42:00.724932 IP cjglap2.52392 > 75.153.171.122.domain: 15913+ A? >>>> news.newsguy.com. (34) >>> >>> Jorgen has explained most of the delay but you also have 4s delay here >>> waiting for a DNS response from _gateway, whatever that is. >>> >>> (In general I suggest using the -n flag to tcpdump so that it doesn’t do >>> its own DNS lookups.) >> >> I'll try that. I suspect that something isn't set up properly >> in my gateway. Just what do those A?, AAAA?, and PTR? flags mean? > > A? news.newsguy.com: > A request for the IPv4 addresses for news.newsguy.com. > AAAA? news.newsguy.com: > A request for the IPv6 addresses for news.newsguy.com. > PTR? 1.0.168.192.in-addr.arpa: > A requeswt for the names corresponding to 192.168.0.1. Thanks. Looks like it's time to study the tcpdump man page... -- /~\ Charlie Gibbs | "Some of you may die, \ / <cgibbs@kltpzyxm.invalid> | but it's sacrifice X I'm really at ac.dekanfrus | I'm willing to make." / \ if you read it the right way. | -- Lord Farquaad (Shrek)
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