Cannot connect to beaglebone.local - unix

I need to know how to connect to a beaglebone (or beagleboard) with SSH when I plug it into a new network with an ethernet cable like this:
$ ssh root#beaglebone.local
So far I've only been able to access it like this, if I know the IP address:
$ ssh root#<ip_address>
But I don't always know the IP address of the board on new networks so I'm hoping to access it with with a name like: beaglebone.local.
Right now when I try to do this I get this error:
"ssh: Could not resolve hostname beaglebone.local: nodename nor servname provided, or not known"
I checked the hostname and hosts files, and added "127.0.0.1 beaglebone" to the hosts on the beaglebone, but not sure what else I can do?
# cat /etc/hostname
beaglebone
# cat /etc/hosts
127.0.0.1 localhost.localdomain localhost
127.0.0.1 beaglebone

I had a similar issue running my beaglebone on Angstrom-Cloud9-IDE-GNOME-eglibc-ipk-v2012.05-beaglebone-2012.04.22.img.xz. In this distribution, "beaglebone.local" should appear on the network after the system boots.
About 50% of the time after reboot, "beaglebone.local" would not appear on the network (although the bone would be available by IP address). When this happened, "systemctl status avahi-daemon.service" showed that the avahi-daemon failed with "exit code 255". Interestingly, a subsequent "systemctl start avaihi-daemon.service" would always be successful and "beaglebone.local" would appear on the network.
Also "journalctl | grep avahi" returned a single message stating something like "Daemon already runnin gon PID NNN".
So, I "fixed" the problem by adding the line "ExecStartPre=/bin/rm -f /var/run/avahi-daemon/pid" to the [Service] section of /lib/systemd/system/avahi-daemon.service. With this addition, "beaglebone.local" now appears on the network 100% of reboots.
I say "fixed" (i.e., in quotes) because I have not been able to track down the root cause that is leaving around the stray avahi pid file(s) and thus don't have a true fix.
-- Frank

For 'beaglebone.local' to work, your host machine must recognize Zeroconf. The BeagleBone uses Avahi to tell other systems on the LAN that it is there and serving up applications and that it should be called a 'beaglebone'. If there are more than one, the second one is generally called 'beaglebone-2.local'.

I hate answering my own questions. The following hack will work until a better way emerges:
This shell script (where xxx.xxx.xxx is the first three numbers in your computer's IP) will find your beaglebone or beagleboard (that is plugged-into ethernet on a new network with DHCP) by looping through all the ip address on the subnet and attempting to login to each as root. If it finds one then try your password. If it doesn't work just hit enter until the loop starts again. If it doesn't find the board then something else is probably wrong.
for ip in $(seq 1 254); do ssh root#xxx.xxx.xxx.$ip -o ConnectTimeout=5; [ $? -eq 0 ] && echo "xxx.xxx.xxx.$ip UP" || : ; done
UPDATE 1
Today I plugged-in the beaglebone and saw Bonjour recognize that it joined the network. So I tried it and it worked. No idea why it decided to all of the sudden but it did. Strange, but true.

I had this issue quite often with Mac OS X 10.7. But unlike Frank Halasz "systemctl status avahi-daemon.service" shown no failure. And in fact the problem was on the Mac side. Restarting Bonjour with the following commands fixed the issue.
$ sudo launchctl unload /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
$ sudo launchctl load -F /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist

Related

Ubuntu (Oracle VM) - Mounted Samba shares hang indefinitely

I have a VM instance on Oracle Cloud (Ubuntu 22.04) set up with ZeroTier to act as a web server for some services that should work with my local Synology NAS.
For some of those services I also need to mount three SMB shares from my NAS with the ZeroTier tunnel, but I can't make it work.
I used mount and mount.cifs plenty of times with automounting too, this time it acts very strange:
running the mount command seems to succeed from the console, but /var/log/syslog reads
CIFS: VFS: \\XXX.XXX.XXX.XXX has not responded in 180 seconds.
Reconnecting...
if trying to access one of the shares (ls or lsof or cd or any other command), it succeeds for only one of the shares (always the same one), but only for the first time any command is given:
$ ls /temp
folder1 folder2 folder3
any other following command just "hangs" as if they system is working on something, but it stays like that indefinitely most of the times:
$ ls /temp
█
Just a few times it spits out this error
lsof: WARNING: can't stat() cifs file system /temp
Output information may be incomplete.
ls 1475 ubuntu 3r DIR 0,44 0 123207681 /temp
findmnt reads:
└─/temp //XXX.XXX.XXX.XXX/Downloads cifs rw,relatime,vers=2.0,cache=strict, username=[redacted],uid=1005,noforceuid,gid=0,noforcegid,addr=XXX.XXX.XXX.XXX,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,rsize=65536,wsize=65536,bsize=1048576,echo_interval=60,actimeo=1
for the remaining two "mounted" shares, none of them seems to respond to any command, not even the very first command, and they just hang like the one share that, at least, lets me browse for one time;
umount and umount -l take at least 2-3 minutes to successfully unmount the shares.
Same behavior when using smbclient and also with NFS shares from the same NAS.
What I have already tried:
update kernel and all packages;
remove, purge and reinstall cifs-utils, smbclient and so on...
tried mounting the same shares in another client / node within the ZeroTier network and it works just fine; also browsing from Windows and Android file manager apps with and without ZeroTier works flawlessly;
tried all SMB versions including SMBv3 and SMBv1 (CIFS);
tried different browsing or mounting methods / commands including mount, mount.cifs, autofs, smbclient;
tried to debug what happens behind the console, but didn't found anything that seems related to this in logs, htop or anything else. During the "hanging" sessions there is no spike in CPU, RAM or Network usage in either the Oracle VM or Synology NAS;
checked, reset and reconfigured all permissions on my NAS for shares, folders and files recursively and reconfigured users groups permissions.
What I haven't tried yet (I'll try as soon as possible):
reproduce this on another Oracle VM configured the same as the faulty one and another with a different base image (maybe Oracle Linux?);
It seems to me that the mount.cifs process doesn't really succeeds in mounting the share correctly, as it doesn't show as such anywhere. It also seems an issue not related to folder/file permissions, but rather something related to networking?
A note on something that may or may not be related to this: ZeroTier on my Synology NAS does not seems to work with IPv4 only - it remains OFFLINE. The node goes ONLINE only when IPv6 is enabled, but I must say that this is the only node in my ZT network that shows a IPv6 as public IP in the ZT web GUI - the other nodes show IPv4 public addresses.
If anyone has any clue on this, I'll be happy to support and reproduce any advice. Thank you!
I'm using YailScale, but I presume it will work the same.
You need to add the port 445 to /etc/iptables/rules.v4 just under the SSH setup like below:
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 445 -j ACCEPT (like this)
Then you need to edit the interfaces in /etc/samba/smb.conf to:
interfaces = lo tailscale0 100.0.0.0/24
Obviously, my interface is tailscale0, but yours will be different. Use ip link show to find yours. You may also need to change your IP range to suit ZeroTeirs, such as 100.0.0.0/24, which is what tailscale uses.
Then reboot!
I couldn't get it working without doing this.

Amazon EC2 Ubuntu 20 - DNS resolution doesn't work

I posted my solution too. I hope this saves someone else a lot of time.
I have an EC2 instance running Ubuntu 20. DNS resolution never works, or fails a lot.
My file /etc/resolv.conf has
nameserver 127.0.0.53
The file is not a symlink, and I can certainly edit it to use nameserver 8.8.8.8 ,
But the file periodically gets overwritten and the 127.0.0.53 (or something similar) is back.
I just want dns to work!
See my solution below.
Get your nic's name from a config file.
cat /etc/netplan/50-cloud-init.yaml
On my system, amazon sets the nic name to ens5.
As root create new file: /etc/netplan/99-custom-dns.yaml
with the following content.
Replace ens5 with your nic's name.
network:
version: 2
ethernets:
ens5:
nameservers:
addresses: [8.8.8.8]
dhcp4-overrides:
use-dns: false
Reboot
sudo shutdown -r now
Verify. After the reboot you can try pinging something by name
ping yahoo.com
or you can view the output of:
systemd-resolve --status
Done
Here's a link to the Amazon help doc, though it misses the nontrivial detail about your nic's name:
https://aws.amazon.com/premiumsupport/knowledge-center/ec2-static-dns-ubuntu-debian/

Network traffic through a particular port using iftop

I have a process using https. I found its PID using ps and used the command lsof -Pan -p PID -i to get the port number it is running on.
I need iftop to see the data transfer. The filter I am using now is
iftop -f "port http 57787".
I don't think this is giving me the right output.
Can someone help me the right filter to use with iftop so that I know the traffic going through only this port?
I can see 2 problems here:
1/ Is that a typo? The correct option for filtering is -f (small "f"). -F (capital "F") option is for net/mask.
2/ Though not explicitly stated by iftop documentation, the syntax for filtering seems to be the pcap one from the few examples given (and using ldd I can see that yes, the iftop binary is linked with libpcap). So a filter with http is simply not valid. To see the doc for pcap filtering syntax, have a look at pcap-filter (7) - packet filter syntax man page. In your example, a filter such as "tcp port 57787" would be OK. pcap does not do layer 5 and above protocol dissection such as http (pcap filters are handled by BPF in the kernel, so above layer 4 you're on your own, because that's none of the kernel business).
All in all, these looks like iperf bugs. It should refuse your "-F" option, and even with "-f" instead exit with an error code because pcap will refuse the filter expression. No big deal, iftop is a modest program. See edit bellow.
EDIT:
I just checked iftop version 1.0pre4 source code, and there is no such obvious bug from a look at set_filter_code() and its caller packet_init() in iftop.c. It correctly exit with error, but...
Error 2, use the "-f" option, but your incorrect filter syntax:
jbm#sumo:~$ sudo iftop -f "port http 57787"
interface: eth0
IP address is: 192.168.1.67
MAC address is: 8c:89:a5:57:10:3c
set_filter_code: syntax error
That's OK.
Error 1, the "-F" instead of "-f", there is a problem:
jbm#sumo:~$ sudo iftop -F "port http 57787"
(everything seems more or less OK, but then quit the program)
Could not parse net/mask: port http 57787
interface: eth0
IP address is: 192.168.1.67
MAC address is: 8c:89:a5:57:10:3c
Oops! "Could not parse net/mask: port http 57787"! That's a bug: it should exit right away.

Serial communication between QEMU host and guest

I'm trying to set up a pair of serial ports between my QEMU host (Debian Jessie x86_64) and guest (also Debian Jessie, but on ARM). Everything except the serial port part works.
I'm really new to QEMU so there might be a better way but I've tested the following flags when running QEMU:
-chardev tty,id=mytty,path=/dev/pts/2 (/dev/pts/2 & 3 are up with socat)
-chardev pty,id=mypty QEMU opens a PTY but when I try to read or write from host get permission denied.
In either case I can't find the ports in my guest. /dev/pts is empty and in /dev there are only tty and ttyAMA3. So, my problem is setting up communication in general and I'm especially curious on where the ports are on my guest.
I found a solution to my own question. First the device tree was incomplete so I needed to add 3 additional uart ports. That's the reason I could not find my ports in the guest.
Second, I needed to tell QEMU to use on of the ports as stdio: -append ... console=ttyAMA3 and -serial mon:stdio. Then I'm able to, with -serial pty, link QEMUs ttyAMA* to pts/* on the host.

Issue with ping and opkg update on Beaglebone black

I'm new with BeagleBone Black, i'm using Angstrom default distro, often i have trouble with ping,opkg update and ssh.
BeagleBone Black has 2 Network Interface, the virtual one (On USB) and the phisical eth0.
I can connect with SSH only with the USB ip, in the other i obtain:
Write failed: Broken pipe
And I've seen a lot of problems during ping and during opkg update.
OPKG stay sometimes undefinitly on this screen:
Downloading http://feeds.angstrom-distribution.org/feeds/v2012.12/ipk/eglibc/armv7a-vfp-neon/base/Packages.gz.
With no results.
And Ping often can't resolve ping to google.it
Someone had similar issues?
Thanks
I ran into a similar issue, this thread might prove helpful in fixing the opkg update problem. Most of the people in that thread do some variation of the following:
Boot your BBB and log in via SSH.
Edit /etc/resolv.conf to add Google's public DNS server:
# cat "nameserver 8.8.8.8" >> /etc/resolv.conf
Run
# route add default gw 192.168.7.1
Run opkg update and upgrade:
# opkg update
# opkg upgrade
Keep in mind, that your changes to the /etc/resolv.conf file will be lost at reboot. I have yet to investigate why.

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