ios command line console log viewing

use "idevice_id --list" to list the UUIDs.
use "deviceconsole" to actually view the logs
deviceconsole -u <UUID>

unbrick TPLINK Archer C7 V2 (2017-05 from Amazon)

I bricked my Archer C7 v2 with bad configuration.

TFTP boot didn't work for me. It turned out that the product id doesn't match.

Had to connect to console.

1. The pinout is as follows. The warning on this page (https://wiki.openwrt.org/toh/tp-link/tl-wdr7500#tftp_recovery_de-bricking) itself is wrong.

2. I used the Openwrt Snapshot image. I tried the official image from TPLink website but that didn't work. I didn't try the "cut" process described in the above link.

3. The command is as follows

type "tpl" really fast at boot time to stop the autoboot

tftpboot 0x81000000 [name of your firmware file].bin
erase 0x9f020000 +f80000
cp.b 0x81000000 0x9f020000 0xf80000
reset

That's it.

socket buffer size

To find the current socket buffer size:

getsockopt(fdsocket,SOL_SOCKET,SO_RCVBUF,(void *)&n, &m);

getsockopt(fdsocket,SOL_SOCKET,SO_SNDBUF,(void *)&n, &m);

To find out more, do "man getsockopt"

To find the current bytes in the socket's buffer:

ioctl(fd,FIONREAD,&bytes_available)

ioctl(fd,FIONWRITE,&bytes_available)

To find out more, do "man ioctl"

FreeBSD recompile kernel

Download:
ftp://ftp.freebsd.org/pub/FreeBSD/releases/amd64/amd64/10.3-RELEASE/src.txz

untar this to /usr/src

Go to the kernel source directory which contains the configurations.

cd /usr/src/sys/amd64/conf

Create a folder named kernel in the home directory of root user i.e. /root.

mkdir /root/kernels

config -x /root/kernels/MYKERNEL

The above command generates the current configuration of the kernel

Now you can add the options you want to change.

Create a soft link in the /usr/src/sys/amd64/conf named “MYKERNEL” which links to /root/kernels/MYKERNEL file.

ln -s /root/kernels/MYKERNEL

Goto the folder created above.

cd /root/kernels/

To build a file which contains all available options, run the following commands.

cd /usr/src/sys/amd64/conf
make LINT

Goto the main source folder.

cd /usr/src

Build and Install the new kernel with reference from the file “MYKERNEL”.

make buildkernel KERNCONF=MYKERNEL
make installkernel KERNCONF=MYKERNEL

Now reboot the machine to boot into the new kernel you just created now.

use "uname -a" and "sysctl -a" to check


Enable multi routing table in the kernel:
https://www.mmacleod.ca/2011/06/source-based-routing-with-freebsd-using-multiple-routing-table/

FreeBSD dump current kernel config

config -x /boot/kernel/kernel

Adding swap to your VM

sudo fallocate -l 1G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
sudo swapon --show
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

seafiles upload error

The solution:
I needed to go into the webui system admin -> settings and change FILE_SERVER_ROOT to be seafile.example.com/seafhttp as per the local help text.

Proxy settings in Windows 10, LAN settings

right click start -> control panel -> internet options -> connections tab -> LAN settings

R7000 serial consle

With the top facing up, and Ethernet ports facing away from you, i.e. the 4 console pins on the right bottom of the board, the pinout from left to right is (yellow,red,green for my personal setup):

RX, which should connects to TX of your CP2102
TX
GND
Unused

openwrt kernel config change

In OpenWRT build, to change kernel config, you need to do the following:
1. make kernel_menuconfig CONFIG_TARGET=subtarget
This updates the .config file in build_dir/Linux-xxxxx
2. copy the file .config from the above directory to "target/Linux/your-board-name/config-3.14"
3. make V=99
The make command will copy the kernel config file from target/Linux to build_dir

Reference:
https://wiki.openwrt.org/doc/howto/build

golang vim-go setup

1. start with a fresh ~/.vim directory
2. install vim-plug if don't have it:

curl -fLo ~/.vim/autoload/plug.vim --create-dirs \
    https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim

3. add the following to your .vimrc file
call plug#begin()
Plug 'tpope/vim-sensible'
Plug 'fatih/vim-go'
Plug 'tmhedberg/matchit'
call plug#end()
au FileType go nmap <C-K> <Plug>(go-doc)
let g:go_fmt_command = "goimports"4. inside vim, run "PlugInstall". This installs the plugins specified above. Restart vim. All plugins should be working now.
5. For vim-go, run ":GoInstallBinaries" to install missing tools needed by vim-go
6. Now Shift-K/Ctrl-K should run go-doc for the keyword under cursor.

 Note for go-doc to work correctly, the go source code file has to be in $GOPATH/src/package-name. It cannot not be a symlink outside of GOPATH. It cannot be a raw *.go file under $GOPATH/src either. It needs to be under a package directory.

windows 10 folder sort slow in file explorer

I solved this by unchecking the "Allow Files in the folder to have contents indexed in addition to file properties" option. You do this by first getting the Properties of the folder, then on the General tab press the Advanced button in the Attributes section. Apply the changes to the folder and , subfolders and files.      

debian/ubuntu snmp has lots of "error on subcontainer ‘ia_addr’ insert (-1)" reports in /var/log/syslog

Modifying /etc/defaults/snmpd and setting "-Lsd" to "-LS6d" in SNMPDOPTS and TRAPDOPTS hides the error message (as suggested by http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=559109).

Or you can use  `sed -i "s|-Lsd|-LS6d|" /etc/default/snmpd`  to fix the problem.

solve kvm soft lockup

Update: setting to jiffies on my guest seems to be the most stable (no lockups yet in the last 24 hours) Original Post: I googled around and by adding clocksource=jiffies to my kernel i fixed it. Instead of jiffies you could also try "pit". This is for the guest OS. You can also use kvm-clock if that is available to you. To check, run the following commands and see whether kvm-clock is available # cat /sys/devices/system/clocksource/clocksource0/available_clocksource tsc hpet acpi_pm jiffies # cat /sys/devices/system/clocksource/clocksource0/current_clocksource tsc

Some people say that the best option for a precise clock on the guest is to use the kvm-clock source (pvclock) which is synchronized with clock's host.

There are also reports of disabling C-states in the BIOS.

gvim set size and color scheme

put this in ~/_vimrc:

set lines=51 columns=200
winpos 56 56
colorscheme desert

batteries, material, voltage

Carbon zinc - non-reversible, 1.5v

Alkaline - non-reversible (basically, but some reversibility can be forced) 1.5 v

NiCd - reversible - 1.2v nominal, 1.35v fully charged, 0.9v discharged

NiMH - reversible - 1.2 v nominal, 1.35 - 1.4v fully charged, 1.0 v discharged

Lead Acid - reversible, 2.0v discharged, 2.3v charged

Lithium Polymer - reversable - 3.7v nominal, 4.2v fully charged, 3.0 discharged

Lithium Ion (LiFePO4) - reversable - 3.3v nominal, 3.6v fully charged, 2.8v discharged  

hexdump is awesome

It can dump binary with any specified format

hexdump -e '"optional-start" iterations/number_of_bytes "format" "optional-ending"'

Example 1:

  hexdump -e '16/1 "%02X " "\n"' x.bin

dumps 16 bytes in a row one-byte-at-a-time, and then adds line return at the row.

To add an offset to each line in the format of 0x0000:

  hexdump -e '"0x%04_ax " 16/1 "%02X "  "\n"'

Example 2:
  hexdump -e '"[" 12/1 "%02 " "]\n"' x.bin

dumps 12 bytes in a row with [ in the beginning and ] at the end.

Nice vim cheatsheet

http://www.viemu.com/a_vi_vim_graphical_cheat_sheet_tutorial.html

Increasing a KVM Virtual Machine Disk when using LVM and ext4

Scenario: I am running several virtual machine guests using QEMU/KVM. Both the host and guest operating systems are Ubuntu 12.04 LTS. The guests are raw images (as opposed to QEMU qcow2 or disk partitions). My instructions for setting up the virtual machines are here. One of the guests image is stored on the host as:

sgordon@host:~$ ls -lhs /var/vm/
total 14G
14G -rwxr-xr-x 1 libvirt-qemu kvm 20G May 18 14:26 it.img

Currently the image is allocated 20GB of space. But note that as Linux ext4 file systems support sparse files, it only takes up 14GB on the disk, as the guest is only using 14GB of the 20GB space available. (The -s option for ls shows the actual size). In the guest virtual machine I am using LVM and ext4 filesystems.
My goal is to increase the size of the guests hard disk, i.e. increase the raw image size. In this case I will increase it from 20GB to 45GB. Mathew Branwell gives a detailed description of the steps involved. I've basically copied his instructions, with some minor changes to resizing the guest image. In summary the steps are:

1. On the host: Increase the size of the guests image
2. On the guest: Increase the disk partition
3. On the guest: Increase the LVM physical and logical volumes
4. On the guest: Increase the file system size

Note that these steps only apply for increasing the size. Decreasing the size is a bit different and has greater potential of data loss.

Guest: Shutdown the Guest Virtual Machine

Before getting started, lets just summarise some details about the guest, in particular the LVM Physical Volumes, Logical Volumes and filesystems. Note that in the examples guest is shown in the prompt indicating the commands are run in the guest (as opposed to the host).

sgordon@guest:~$ sudo pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/vda5  vmit lvm2 a-   19.81g    0 
sgordon@guest:~$ sudo lvs
  LV   VG   Attr   LSize Origin Snap%  Move Log Copy%  Convert
  home vmit -wi-ao 5.84g                                      
  root vmit -wi-ao 4.66g                                      
  tmp  vmit -wi-ao 4.66g                                      
  var  vmit -wi-ao 4.66g  
sgordon@guest:~$ df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/vmit-root  4.7G  1.8G  2.7G  40% /
udev                   728M  4.0K  728M   1% /dev
tmpfs                  293M  264K  293M   1% /run
none                   5.0M     0  5.0M   0% /run/lock
none                   732M     0  732M   0% /run/shm
/dev/vda1              189M   24M  155M  14% /boot
/dev/mapper/vmit-tmp   4.7G  198M  4.3G   5% /tmp
/dev/mapper/vmit-var   4.7G  1.3G  3.2G  28% /var
/dev/mapper/vmit-home  5.9G  2.5G  3.1G  45% /home

The first step is to shutdown the guest virtual machine:

sgordon@guest:~$ sudo shutdown -P now

Broadcast message from sgordon@guest
 (/dev/pts/0) at 14:51 ...

The system is going down for power off NOW!

Host: Increase the Virtual Machine Image Size

Now resize the image on the host machine:

sgordon@host:~$ sudo qemu-img resize /var/vm/guest.img +25G
Image resized.

This increases the guest image file by 25GB. To check:

sgordon@host:~$ ls -lhs /var/vm/
total 14G
14G -rwxr-xr-x 1 root root 45G May 18 14:53 guest.img

Now start and login to the guest for the remaining steps:

sgordon@host$ sudo virsh start guest
Domain it started
sgordon@host$ ssh guest

Guest: Increase the Partition Size

First on the guest we need to increase the partition sizes using fdisk:

sgordon@guest:~$ sudo fdisk /dev/vda

Command (m for help): 

fdisk takes single letter commands as described in the help. Using the command p to print the current partitions:

Command (m for help): p

Disk /dev/vda: 48.3 GB, 48318382080 bytes
16 heads, 63 sectors/track, 93622 cylinders, total 94371840 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00079e72

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048      391167      194560   83  Linux
/dev/vda2          393214    41940991    20773889    5  Extended
/dev/vda5          393216    41940991    20773888   8e  Linux LVM

Note that my disk (/dev/vda) is 48.3GB, but my partitions are only using 20GB (20773888 blocks).
Be careful! Your partitions will be different from mine. Use the devices/sizes for your partitions in the following examples. I have an initial boot partion on /dev/vda1 followed by an extended partition with Linux LVM.
I want to increase the size of the Extended and Linux LVM partitions by first deleting them and then creating new ones of the same type but different size. Note the device names and system/IDs in your partition table.
To delete partitions use the d command and specifiy the partition number (2 and 5 in my case):

Command (m for help): d
Partition number (1-5): 5

Command (m for help): d
Partition number (1-5): 2

Command (m for help): p

Disk /dev/vda: 48.3 GB, 48318382080 bytes
16 heads, 63 sectors/track, 93622 cylinders, total 94371840 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00079e72

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048      391167      194560   83  Linux

Now lets create new partitions. I will use the same structure as before but use the entire disk. Use the n command:

Command (m for help): n
Partition type:
   p   primary (1 primary, 0 extended, 3 free)
   e   extended
Select (default p): e
Partition number (1-4, default 2): 2
First sector (391168-94371839, default 391168): <ENTER> 
Using default value 391168
Last sector, +sectors or +size{K,M,G} (391168-94371839, default 94371839): <ENTER>
Using default value 94371839

I create a new extended partition number 2 using the default first and last sectors. I also need to create the second new logical partition:

Command (m for help): n
Partition type:
   p   primary (1 primary, 1 extended, 2 free)
   l   logical (numbered from 5)
Select (default p): l
Adding logical partition 5
First sector (393216-94371839, default 393216): <ENTER> 
Using default value 393216
Last sector, +sectors or +size{K,M,G} (393216-94371839, default 94371839): <ENTER>
Using default value 94371839

I also need to specify the type of the logical partition, i.e. Linux LVM. From the original partition table the Id of the Linux LVM system is 8e:

Command (m for help): t
Partition number (1-5): 5
Hex code (type L to list codes): 8e
Changed system type of partition 5 to 8e (Linux LVM)

The resulting partition table follows. Note that is is the same structure as the original table but the size of the last two partitions (/dev/vda2 and /dev/vda5) have changed from 20GB to about 45GB.

Command (m for help): p

Disk /dev/vda: 48.3 GB, 48318382080 bytes
16 heads, 63 sectors/track, 93622 cylinders, total 94371840 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00079e72

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048      391167      194560   83  Linux
/dev/vda2          391168    94371839    46990336    5  Extended
/dev/vda5          393216    94371839    46989312   8e  Linux LVM

If your partition table is correct then the last step is to write those changes:

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
sgordon@guest:~$

Note the warning: you need to reboot for the new partition table to be read:

sgordon@guest:~$ sudo shutdown -r now
Broadcast message from sgordon@it
 (/dev/pts/0) at 15:15 ...

The system is going down for reboot NOW!

Guest: Increase the LVM Physical and Logical Volume Sizes

Note that this step only applies if you are using LVM.
After rebooting and logging back in, we need to update LVM. First note the current size of the Physical Volume. On my guest virtual machine I have one physical volume:

sgordon@guest:~$ sudo pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/vda5  vmit lvm2 a-   19.81g    0 

We need to resize the physical volume:

sgordon@guest:~$ sudo pvresize /dev/vda5
  Physical volume "/dev/vda5" changed
  1 physical volume(s) resized / 0 physical volume(s) not resized
sgordon@guest:~$ sudo pvs
  PV         VG   Fmt  Attr PSize  PFree 
  /dev/vda5  vmit lvm2 a-   44.81g 25.00g

The physical volume now takes the full space of 45GB, and there is 25GB free. We will extend the Logical Volumes to use that extra 25GB. In my case I have four logical volumes: home, root, tmp and var (and the correpending directories are mount to them). In this case I want to increase the size of the home and var volumes by 15GB and 10GB, respectively. I will use lvextend which requires you to specify the logical volume relative to the volume group.

sgordon@guest:~$ sudo vgs
  VG   #PV #LV #SN Attr   VSize  VFree 
  vmit   1   4   0 wz--n- 44.81g 25.00g

The name of my volume group is vmit. So now lets extend the two logical volumes:

sgordon@guest:~$ sudo lvextend -L +15G /dev/vmit/home
  Extending logical volume home to 20.84 GiB
  Logical volume home successfully resized
sgordon@guest:~$ sudo lvextend -L +10G /dev/vmit/var
  Extending logical volume var to 14.66 GiB
  Logical volume var successfully resized

The result, as shown below, is the volume group now has no space free and the home>/kbd> and var logical volumes are now 21GB and 15GB, respectively.

sgordon@guest:~$ sudo vgs
  VG   #PV #LV #SN Attr   VSize  VFree
  vmit   1   4   0 wz--n- 44.81g    0 
sgordon@guest:~$ sudo lvs
  LV   VG   Attr   LSize  Origin Snap%  Move Log Copy%  Convert
  home vmit -wi-ao 20.84g                                      
  root vmit -wi-ao  4.66g                                      
  tmp  vmit -wi-ao  4.66g                                      
  var  vmit -wi-ao 14.66g                                      

Guest: Increase the Filesystem Sizes

The last step is to grow the filesystems to use the entire logical volume. Currently the filesystems sizes are still the original sizes, as shown below.

sgordon@guest:~$ df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/vmit-root  4.7G  1.8G  2.7G  40% /
udev                   728M  4.0K  728M   1% /dev
tmpfs                  293M  252K  293M   1% /run
none                   5.0M     0  5.0M   0% /run/lock
none                   732M     0  732M   0% /run/shm
/dev/vda1              189M   24M  155M  14% /boot
/dev/mapper/vmit-tmp   4.7G  198M  4.3G   5% /tmp
/dev/mapper/vmit-var   4.7G  1.3G  3.2G  28% /var
/dev/mapper/vmit-home  5.9G  2.5G  3.1G  45% /home

In my case I am using ext4 filesystems and using resize2fs I can increase their size online, that is, while they're mounted. If you have a different filesystem (or possibly older kernel) online resizing may not be possible; you may need to unmount the filesystems first.

sgordon@guest:~$ sudo resize2fs /dev/vmit/home
resize2fs 1.42 (29-Nov-2011)
Filesystem at /dev/vmit/home is mounted on /home; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/vmit/home to 5463040 (4k) blocks.
The filesystem on /dev/vmit/home is now 5463040 blocks long.

sgordon@guest:~$ sudo resize2fs /dev/vmit/var
resize2fs 1.42 (29-Nov-2011)
Filesystem at /dev/vmit/var is mounted on /var; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/vmit/var to 3842048 (4k) blocks.
The filesystem on /dev/vmit/var is now 3842048 blocks long.

Note that the resize takes some time. Finally, check the new sizes:

sgordon@guest:~$ df -h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/vmit-root  4.7G  1.8G  2.7G  40% /
udev                   728M  4.0K  728M   1% /dev
tmpfs                  293M  252K  293M   1% /run
none                   5.0M     0  5.0M   0% /run/lock
none                   732M     0  732M   0% /run/shm
/dev/vda1              189M   24M  155M  14% /boot
/dev/mapper/vmit-tmp   4.7G  198M  4.3G   5% /tmp
/dev/mapper/vmit-var    15G  1.3G   13G   9% /var
/dev/mapper/vmit-home   21G  2.5G   18G  13% /home

I now have a 15GB /var filesystem and a 21GB /home filesystem.


Source: https://sandilands.info/sgordon/increasing-kvm-virtual-machine-disk-using-lvm-ext4

Where to download broadcom Netgear R7000 toolchain binary

The toolchain file is hndtools-arm-linux-2.6.36-uclibc-4.5.3.tar.bz2

Download URL: https://sourceforge.net/projects/nvg599.arris/files/

This tarball also contains the Broadcom code drop bcm963xx_4.06L.03_consumer_release.tar.gz, which was created using Broadcom's source code redistribution process, bcm47xx.tar.bz2 which is the 5GHz code, hndtools-arm-linux-2.6.36-uclibc-4.5.3.tar.bz2, which is the toolchain for the 5Ghz code, and axis.tar.bz2 which is the code that runs on the main SOC.