/usr/local/bin/raspibolt and https://bitnodes.earn.com/api/v1/nodes/me-${public_port} about raspibolt

[robclark56]

I think it was because I updated my raspibolt script to bash instead of /bin/sh
#!/bin/bash

In bash you check equality of STRINGS with ==.
And I converted $public_check to a string as follows: "$public_check" (added quotes)

But by all means do what works. I am not an expert on shell scripting at all.

:-)

[Stadicus]

Good catch, might be the cause for some of the issues raised here. Do you know of a different method to check the public availability of the Bitcoin node?

[robclark56]

Sorry no.

Tried without success to fine an alternative service.

[robclark56]

Found a solution. The Raspibolt itself can check if a port is open. While I do like the idea for a completely external check e.g. from https://bitnodes.earn.com, as we see - that can cause problem.

in the raspibolt script, change

public_check=$(curl -s https://bitnodes.earn.com/api/v1/nodes/me-${public_port}/ | jq .success)
if [ $public_check = "true" ]; then

to

public_check=$(timeout 2s nc -z ${public_ip} ${public_port}; echo $?)
if [ "$public_check" == "0" ]; then

[Stadicus]

Hi @robclark56, I tried to figure out how this should work. As long as I use my own ip address, netcat always return no value. Which means 'you are public', I guess?

Am I missing something?

[robclark56]

nc -z IP PORT returns:

• 0 if success (ie PORT on IP is open)
• Non-Zero if failure (ie Port is not open)

Here are my examples (8333 is open, 12345 is not)

admin ~  ฿  nc -z  106.68.62.191 8333
admin ~  ฿  echo $?
0
admin ~  ฿  nc -z  106.68.62.191 12345
[..... long wait ....]
admin ~  ฿  echo $?
1

And here it is verbose

admin ~  ฿  nc -vz  106.68.62.191 8333
Connection to 106.68.62.191 8333 port [tcp/*] succeeded!
admin ~  ฿  nc -vz  106.68.62.191 12345
nc: connect to 106.68.62.191 port 12345 (tcp) failed: Connection timed out

But you indicate you get 'success' for all ports. That should not happen.

Try the verbose (-zv) option on a closed port.

[Stadicus]

Ok, works great! Was not aware that the return value needs to be printed...

[Stadicus]

Any special reason you went with the == operator? I get the following error message:

./20-raspibolt-welcome: 117: [: 0: unexpected operator

When using the normal = operator, it works fine.

[Stadicus]

Updated the welcome script, thanks @robclark56!
PR #121

[Janaka-Steph]

Hello @Stadicus @robclark56 !
I have some issues checking the public availability of my node (on testnet) with nc -vz IP PORT. As my node try to access my public IP address from behind a NAT, he got confused. This is a classic networking problem.

Reading this blog post System: Accessing Public IP address from behind NAT I found what I first thought was a solution, which is adding a rule in iptables to convert my public IP to my local IP.
$ sudo iptables -A INPUT -p tcp --src 85.220.240.110 --dport 22 -j ACCEPT

$ sudo iptables -L -t nat
Chain OUTPUT (policy ACCEPT)
target       prot    opt          source                 destination
DNAT       all        --            thundroid            85.220.240.110            to:192.168.1.104

It seems to work but in fact it is not checking anything because the request never really leave my local network. So not a proper solution.

It seems that this nc call works seamlessly for some people but I can't figure out why it doesn't work for me. Any ideas? Thank you.