August 2018 - luv-main

strange 6in4 errors - what does "RX errors" mean?
by Russell Coker 29 Sep '18

29 Sep '18

# ifconfig 6in4 6in4: flags=209<UP,POINTOPOINT,RUNNING,NOARP> mtu 1280 inet6 2a01:4f8:140:71f5:1::ffff prefixlen 128 scopeid 0x0<global> inet6 fe80::a08:1 prefixlen 64 scopeid 0x20<link> inet6 fe80::2e04:7ca5 prefixlen 64 scopeid 0x20<link> inet6 fe80::a0a:a01 prefixlen 64 scopeid 0x20<link> sit txqueuelen 1 (IPv6-in-IPv4) RX packets 563 bytes 69361 (67.7 KiB) RX errors 1200 dropped 0 overruns 0 frame 1200 TX packets 600 bytes 164726 (160.8 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 Above is the result of running ifconfig on my 6in4 device. The problem is the "RX errors" which correspond to ICMP packets missing. The system at the far end of the 6in4 link has monitoring that includes "ping6 www.google.com", until recently that was fine, since upgrading to Debian kernel 4.9.0-7-amd64 #1 SMP Debian 4.9.110-1 problems have started. The problems are somewhat intermittent. I don't expect that the recent Debian kernel upgrade broke this, maybe the reboot exposed some other problem. Does anyone know what "RX errors" means in the context of 6in4 interfaces on Linux? Is there any way of getting the kernel to log every error to dmesg or something? I expect this will be a really easy problem to solve once I know what the errors mean. When the errors happen I run tcpdump on the far end of the 6in4 link and see the packets going out, I run tcpdump on the ethernet device and see the encapsulated packets going in, and when I run tcpdump on the 6in4 device I don't see those packets but I do see packets for local ipv6 addresses. Here's the /etc/network/interfaces section from the server: auto 6in4 iface 6in4 inet6 v4tunnel address 2a01:4f8:140:71f5:1::ffff netmask 128 endpoint 203.15.121.80 ttl 64 up ip link set mtu 1280 dev 6in4 up ip route add 2a01:4f8:140:71f5:1::/96 dev 6in4 Here's the /etc/network/interfaces section from the other end: auto 6in4 iface 6in4 inet6 v4tunnel address 2a01:4f8:140:71f5:1::1 netmask 128 endpoint 46.4.124.165 ttl 64 up ip route add 2a01:4f8:140:71f5:1::ffff dev 6in4 up ip link set mtu 1280 dev 6in4 up ip route add 2000::/3 dev 6in4 Here's the result of running tcpdump on the server, those encapsulated packets look ok and should go to the 6in4 device. # tcpdump -i br0 -n host 203.15.121.80 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on br0, link-type EN10MB (Ethernet), capture size 262144 bytes 01:18:57.333752 IP 203.15.121.80 > 46.4.124.165: IP6 2a01:4f8:140:71f5:1::4 > 2404:6800:4006:800::2004: ICMP6, echo request, seq 14, length 64 01:18:58.357831 IP 203.15.121.80 > 46.4.124.165: IP6 2a01:4f8:140:71f5:1::4 > 2404:6800:4006:800::2004: ICMP6, echo request, seq 15, length 64 01:18:59.381702 IP 203.15.121.80 > 46.4.124.165: IP6 2a01:4f8:140:71f5:1::4 > 2404:6800:4006:800::2004: ICMP6, echo request, seq 16, length 64 01:19:00.405686 IP 203.15.121.80 > 46.4.124.165: IP6 2a01:4f8:140:71f5:1::4 > 2404:6800:4006:800::2004: ICMP6, echo request, seq 17, length 64 Any ideas? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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MTP probe of USB drive
by Jason White 26 Aug '18

26 Aug '18

Upon attaching a USB hard drive to an old, but up to date, Linux laptop last weekend, the block device corresponding to the drive was not created. The kernel logs showed that the USB device was probed for mtp support, which failed. After searching the Web, the solution that I found was to create a script in /etc/profile.d containing Export MTP_NO_PROBE=1 Are there better solutions than disabling MTP probes altogether?

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expect script
by cory seligman 20 Aug '18

20 Aug '18

Hi All, I'm having some trouble making expect work. I need it to talk to some vintage equipment over usb serial, and I think I'm getting hung up on opening the port. When the script runs, it just connects to the device and sits there. I can drive it interactively, but it doesn't attempt to automate anything. Any ideas? Thanks. My expect script looks like this: #!/usr/bin/expect -f # device set modem /dev/ttyUSB0 # keep it open exec sh -c "sleep 3 < $modem" & # serial port parameters exec stty -F $modem 2400 raw -clocal -echo -istrip -hup # connect send_user "connecting to $modem, exit with ~,\n" spawn -open [open $modem w+] interact { ~, exit ~~ {send "\034"} } set force_conservative 1 ;# set to 1 to force conservative mode even if ;# script wasn't run conservatively originally if {$force_conservative} { set send_slow {1 .1} proc send {ignore arg} { sleep .1 exp_send -s -- $arg } } set timeout -1 match_max 100000 send -- "\r" send -- "\r" expect ">" send -- "p 7d91\r" expect ">" send -- "p b2ff\r" expect ">" send -- "h\r" expect ">" send -- "td\r" expect "td\r 18 215 12 24 33\r >" send -- "gd 215\r" expect eof

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Compose::Melbourne Functional Programming event coming up, 27-28 August 2018
by Les Kitchen 19 Aug '18

19 Aug '18

Dear fellow LUV members, Compose::Melbourne is running this year for the third time, coming up in just over a week: http://www.composeconference.org/2018-melbourne/ It's a two-day event, aimed at building and supporting the functional-programming community in Melbourne. So if you're at all interested in functional programming, newbie or expert, come along and learn and meet people sharing that interest. I know this is not Linux-specific, but most of the main functional-programming systems are FOSS (and Linux-friendly), and functional programming is being increasingly adopted in industry. Day One, Monday 27 August, is the conference, with a dozen presentations on functional programming (FP) through the day, including keynote "The Unreasonable Effectiveness of Metaphor" by Julie Moronuki, author of the book, Haskell Programming from First Principles. Day Two, Tuesday 28 August, is the "unconference": an informal day of getting together to share FP ideas and experience, although we will be running a few workshops and sessions, including CRASHKELL, an introductory Haskell workshop for beginners. You can read the webpage for more information about the programme and registration. In particular, if you're planning to attend any of the workshops, check the requirements. You'll probably need to bring a laptop, and for some workshops you'll need to install software ahead of time — though we can help you with that on the day if need be. We really want to help build the diversity of the functional-programming community, so we've tried to keep the registration cost as low as possible. But if you'd like to attend, and still face difficulty paying the registration fee, mail me, ljk+compose(a)ljk.id.au. We have a limited number of free tickets available for this purpose. Also feel free to mail me if you have any other questions not answered on the website. Hope to see some of you at Compose::Melbourne! — Smiles, Les (also Compose::Melbourne committee member).

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Happy 25th birthday Debian!
by Andrew Pam 17 Aug '18

17 Aug '18

https://bits.debian.org/2018/08/debian-is-25.html Share and enjoy, Andrew

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Re: Mount Android device as block device via USB?
by Brian May 03 Aug '18

03 Aug '18

Anthony via luv-main <luv-main(a)luv.asn.au> writes: > Depends on the phone, but newer devices these days generally do not present > a mass storage device. They instead expose storage at file level via MTP > (Media Transfer Protocol), as block storage access requires exclusive lock > on partition, and that means background processes using the storage on the > phone must be halted and/or may crash. I recently tried MTP to backup my sdcard data before performing a factory reset and sending my Pixel XL phone in for warranty (microphone not working, seems like a common problem). I found it kept crashing repeatedly after transferring several files, requiring disconnecting and reconnecting the USB cable each time. I eventually gave up trying with USB, and backed up the files with a SSH based sync program instead, over wifi. A bit slower, but at least it worked. This with with a Debian/stretch based system with Gnome installation. -- Brian May <brian(a)linuxpenguins.xyz> https://linuxpenguins.xyz/brian/

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Mount Android device as block device via USB?
by David Zhan 02 Aug '18

02 Aug '18

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Re: [luv-announce] CORRECTED: LUV August 2018 Main Meeting: PF on OpenBSD and fail2ban
by Russell Coker 01 Aug '18

01 Aug '18

On Tuesday, 31 July 2018 9:34:04 PM AEST Andrew Pam via luv-announce wrote: > Another group has the room before us, so we're starting half an hour > later this month. > > 7:00 PM to 9:00 PM Tuesday, August 7, 2018 > Training Room, Kathleen Syme Library, 251 Faraday Street Carlton VIC 3053 I proposed the change from 7pm start to 6:30 when we were in a building that had the doors lock at 7pm, and which was incidentally a little easier to get to from the CBD. Now we are in a building where there is free parking after 6:30. While people are able to pay a small amount of money for parking before 6:30 so they can enter in time I'm sure I'm not the only one who has aimed to park at 6:30 and arrive at about 6:35 to avoid paying. Should we just make the standard meeting time 7pm again? In the years before we had the situation of doors locking at 7pm we didn't have any complaints about a 7pm start. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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