This post is not a question. Its rather verbose documentation on flashing openwrt and installing luci package on Netgear R6260 model. I think it fits here rather than wiki because of its verbosity so i post it here.
I installed on march 17, year 2020. You should spent some time around 1 to 2 hours reading the wiki and documentation on the https://openwrt.org. It will give the necessary knowledge to not feel lost during the process of flashing.
Let's start.
The following version of netgear firmware was installed on the router.
http://www.routerlogin.net/
Router Firmware Version (top left)
V1.1.0.28_1.0.1
I downloaded the following image, i forgot to note the exact url but you should be able to find it easily
$ sha256sum openwrt-ramips-mt7621-netgear_r6260-squashfs-factory.img
2ffbd2924f8a02c67386b6eef793dddb117d0ccbd5fe30eaf921723a6e136100 openwrt-ramips-mt7621-netgear_r6260-squashfs-factory.img
Flashed the image using the netgear web interface(admin page->firmware->update). After i clicked the update button there was a status bar displayed and it was progressing but after some time it disappeared and the web page looked like nothing has happened. The openwrt document said it should reboot. But nothing happened even after few more minutes. So i rebooted and visited http://www.routerlogin.net and it displayed the netgear webgui. So the flash did not happened.
I tried the same as before for the second time. This time the web page showed the following warning.
Warning! The firmware version you are trying to upload is older than the one you had.
Do you still want to continue?
Current Version V1.1.0.28
Uploaded Version V1.0.0.52
I clicked yes and then clicked update after some time there was a 404 error in the center part of the netgear web gui page. I also noticed leds blinking. I refreshed the page and it errored out. I concluded that reboot was happening. After few minutes i tried ssh.
$ ssh root@192.168.1.1
root@OpenWrt:~#
Wow!!!. Got access to ssh shell.
This following was the release info
root@OpenWrt:~# cat /etc/*rele*
DISTRIB_ID='OpenWrt'
DISTRIB_RELEASE='SNAPSHOT'
DISTRIB_REVISION='r12629-6e64039a87'
DISTRIB_TARGET='ramips/mt7621'
DISTRIB_ARCH='mipsel_24kc'
DISTRIB_DESCRIPTION='OpenWrt SNAPSHOT r12629-6e64039a87'
DISTRIB_TAINTS=''
NAME="OpenWrt"
VERSION="SNAPSHOT"
ID="openwrt"
ID_LIKE="lede openwrt"
PRETTY_NAME="OpenWrt SNAPSHOT"
VERSION_ID="snapshot"
HOME_URL="https://openwrt.org/"
BUG_URL="https://bugs.openwrt.org/"
SUPPORT_URL="https://forum.openwrt.org/"
BUILD_ID="r12629-6e64039a87"
OPENWRT_BOARD="ramips/mt7621"
OPENWRT_ARCH="mipsel_24kc"
OPENWRT_TAINTS=""
OPENWRT_DEVICE_MANUFACTURER="OpenWrt"
OPENWRT_DEVICE_MANUFACTURER_URL="https://openwrt.org/"
OPENWRT_DEVICE_PRODUCT="Generic"
OPENWRT_DEVICE_REVISION="v0"
OPENWRT_RELEASE="OpenWrt SNAPSHOT r12629-6e64039a87"
root@OpenWrt:~#
I then tried http://192.168.1.1. It errored out.
I thought may be flashing sysupgrade might bring the web interace(luci). So i downloaed and flashed it.
$ sha256sum openwrt-ramips-mt7621-netgear_r6260-squashfs-sysupgrade.bin
737a493b9191324285e41655962abc3f5db975b07af5a5b6ed170941e96838f4 openwrt-ramips-mt7621-netgear_r6260-squashfs-sysupgrade.bin
$ scp openwrt-ramips-mt7621-netgear_r6260-squashfs-sysupgrade.bin root@192.168.1.1:/tmp/
root@OpenWrt:~# sha256sum /tmp/openwrt-ramips-mt7621-netgear_r6260-squashfs-sysupgrade.bin
737a493b9191324285e41655962abc3f5db975b07af5a5b6ed170941e96838f4 /tmp/openwrt-ramips-mt7621-netgear_r6260-squashfs-sysupgrade.bin
root@OpenWrt:~# sysupgrade -v /tmp/openwrt-ramips-mt7621-netgear_r6260-squashfs-sysupgrade.bin
Saving config files...
etc/config/dhcp
etc/config/dropbear
etc/config/firewall
etc/config/network
etc/config/system
etc/config/wireless
etc/dropbear/dropbear_rsa_host_key
etc/group
etc/hosts
etc/inittab
etc/opkg/keys/0b26f36ae0f4106d
etc/opkg/keys/1035ac73cc4e59e3
etc/opkg/keys/5151f69420c3f508
etc/opkg/keys/72a57f2191b211e0
etc/opkg/keys/792d9d9b39f180dc
etc/opkg/keys/9ef4694208102c43
etc/opkg/keys/b2d571e0880ff617
etc/opkg/keys/b5043e70f9a75cde
etc/opkg/keys/c10b9afab19ee428
etc/opkg/keys/dace9d4df16896bf
etc/opkg/keys/dd6de0d06bbd3d85
etc/opkg/keys/f94b9dd6febac963
etc/passwd
etc/profile
etc/rc.local
etc/shadow
etc/shells
etc/shinit
etc/sysctl.conf
Commencing upgrade. Closing all shell sessions.
Connection to 192.168.1.1 closed by remote host.
Connection to 192.168.1.1 closed.
After upgrade did ssh and it displayed the following banner
*** ssh after upgrade flash
rick2@rick2-TH55B-HD:~/Downloads$ ssh root@192.168.1.1
BusyBox v1.31.1 () built-in shell (ash)
_______ ________ __
| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
-----------------------------------------------------
OpenWrt SNAPSHOT, r12629-6e64039a87
-----------------------------------------------------
=== WARNING! =====================================
There is no root password defined on this device!
Use the "passwd" command to set up a new password
in order to prevent unauthorized SSH logins.
-----------------------------
I visited the webpage http://192.168.1.1 and it errored out. Again luci interface was not available. I read more docs and found that for stable release package the luci interface is not available. As of this writing only stable release was available for this router model.
Then i found this document https://openwrt.org/docs/guide-user/luci/luci.essentials#offline_installation to install luci(web interface) package.
That document has a script to download all the packages but the script did not work because the assumptions about the url path does not hold valid. Looks like the site changed its path slightly. I fixed the bugs in the script downloaded all the packages. I ran the script multiple times changing and commenting some portion every time to download a some set of packages. This task took the majority of the time in installing openwrt firmware.
liblua https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/liblua5.1.5_5.1.5-7_mipsel_24kc.ipk
lua https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/lua_5.1.5-7_mipsel_24kc.ipk
libuci-lua https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/libuci-lua_2020-01-27-e8d83732-3_mipsel_24kc.ipk
libubus https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/libubus20191227_2020-01-05-d35df8ad-1_mipsel_24kc.ipk
libubus-lua https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/libubus-lua_2020-01-05-d35df8ad-1_mipsel_24kc.ipk
uhttpd https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/uhttpd_2020-02-12-2ee323c0-1_mipsel_24kc.ipk
rpcd https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/rpcd_2020-01-05-efe51f41-2_mipsel_24kc.ipk
luci-base https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-base_git-20.076.61489-c259369-1_mipsel_24kc.ipk
liblucihttp https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/liblucihttp0_2019-07-05-a34a17d5-1_mipsel_24kc.ipk
liblucihttp-lua https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/liblucihttp-lua_2019-07-05-a34a17d5-1_mipsel_24kc.ipk
luci-lib-ip https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-lib-ip_git-20.076.61489-c259369-1_mipsel_24kc.ipk
luci-lib-nixio https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-lib-nixio_git-20.076.61489-c259369-1_mipsel_24kc.ipk
luci-theme-bootstrap https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-theme-bootstrap_git-20.076.61489-c259369-1_all.ipk
luci-mod-admin-full https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-mod-admin-full_git-20.076.61489-c259369-1_all.ipk
luci-lib-jsonc https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-lib-jsonc_git-20.076.61489-c259369-1_mipsel_24kc.ipk
luci-mod-status https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-mod-status_git-20.076.61489-c259369-1_mipsel_24kc.ipk
luci-mod-system https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-mod-system_git-20.076.61489-c259369-1_all.ipk
luci-mod-network https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-mod-network_git-20.076.61489-c259369-1_all.ipk
libiwinfo https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/libiwinfo20200105_2020-01-05-bf2c1069-1_mipsel_24kc.ipk
libiwinfo-lua https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/libiwinfo-lua_2020-01-05-bf2c1069-1_mipsel_24kc.ipk
Additional packages to support pppoe
wget https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/rpcd-mod-file_2020-01-05-efe51f41-2_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/rpcd-mod-luci_20191114_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/base/rpcd-mod-iwinfo_2020-01-05-efe51f41-2_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/kmod-ledtrig-default-on_4.14.172-1_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/kmod-ledtrig-heartbeat_4.14.172-1_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/kmod-ledtrig-netdev_4.14.172-1_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/targets/ramips/mt7621/packages/kmod-ledtrig-timer_4.14.172-1_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/packages/cgi-io_19_mipsel_24kc.ipk
wget https://downloads.openwrt.org/snapshots/packages/mipsel_24kc/luci/luci-proto-ppp_git-20.076.61489-c259369-1_all.ipk
Download(wget) all of the above packages and scp to /tmp directory of router
then login in to the router and type
root@OpenWrt:~# opkg install /tmp/*.ipk
reboot and visit http://192.168.1.1/index.html it luci gui should be available.
Thanks to openwrt developers and such an awesome community that created extensive documentation of supported hardwares and other information. You people are awesome.