Run command once a port is listening #69

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Benjamin_Loison · 2025-03-07T17:40:07+01:00

Benjamin_Loison commented

2025-03-07 17:40:07 +01:00

Related to #38.

👍 1

Benjamin_Loison commented

2025-03-07 17:40:25 +01:00

Would help Benjamin_Loison/openssh/issues/68.

Would help [Benjamin_Loison/openssh/issues/68](https://salsa.debian.org/Benjamin_Loison/openssh/-/issues/68).

Benjamin_Loison commented

2025-03-07 17:41:17 +01:00

DuckDuckGo search Linux run command once port listen.

DuckDuckGo search *Linux run command once port listen*.

Benjamin_Loison commented

2025-03-07 17:43:07 +01:00

#44 could help but I am not root on the server I have in mind.

tail /var/log/auth.log

tail: cannot open '/var/log/auth.log' for reading: Permission denied

#44 could help but I am not `root` on the server I have in mind. ```bash tail /var/log/auth.log ``` ``` tail: cannot open '/var/log/auth.log' for reading: Permission denied ```

Benjamin_Loison commented

2025-03-07 17:45:50 +01:00

netstat -tulpn | grep 2224

Output:

(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 127.0.0.1:2224          0.0.0.0:*               LISTEN      -                   
tcp6       0      0 ::1:2224                :::*                    LISTEN      -

netstat -tulpn | grep 2250

Output:

(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)

```bash netstat -tulpn | grep 2224 ``` <details> <summary>Output:</summary> ``` (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) tcp 0 0 127.0.0.1:2224 0.0.0.0:* LISTEN - tcp6 0 0 ::1:2224 :::* LISTEN - ``` </details> ```bash netstat -tulpn | grep 2250 ``` <details> <summary>Output:</summary> ``` (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) ``` </details>

Benjamin_Loison commented

2025-03-07 17:47:28 +01:00

DuckDuckGo and Google search run command on netstat update.

DuckDuckGo and Google search *run command on netstat update*.

Benjamin_Loison commented

2025-03-07 17:58:39 +01:00

inotifywait -e modify /dev/tcp/127.0.0.1/22

Output:

Setting up watches.
Couldn't watch /dev/tcp/127.0.0.1/22: No such file or directory

Source: Benjamin-Loison/LemnosLife-Client/issues/85#issuecomment-1636544466

```bash inotifywait -e modify /dev/tcp/127.0.0.1/22 ``` <details> <summary>Output:</summary> ``` Setting up watches. Couldn't watch /dev/tcp/127.0.0.1/22: No such file or directory ``` </details> Source: [Benjamin-Loison/LemnosLife-Client/issues/85#issuecomment-1636544466](https://github.com/Benjamin-Loison/LemnosLife-Client/issues/85#issuecomment-1636544466)

Benjamin_Loison commented

2025-03-07 18:05:02 +01:00

Bash script:

PORT=2250
 KEY=CENSORED
MESSAGE="`hostname`:$PORT is back online!"
NUMBER_OF_SECONDS_BETWEEN_EACH_TRY=60
while ! (echo -n > /dev/tcp/localhost/$PORT) 2> /dev/null
do
    date
    sleep $NUMBER_OF_SECONDS_BETWEEN_EACH_TRY
done | tee -a logs.txt
curl -G https://lemnoslife.com/CENSORED/notify.php --data-urlencode "message=$MESSAGE" -d key=$KEY

one second and exponential delays do not seem appropriate.

<details> <summary>Bash script:</summary> ```bash PORT=2250 KEY=CENSORED MESSAGE="`hostname`:$PORT is back online!" NUMBER_OF_SECONDS_BETWEEN_EACH_TRY=60 while ! (echo -n > /dev/tcp/localhost/$PORT) 2> /dev/null do date sleep $NUMBER_OF_SECONDS_BETWEEN_EACH_TRY done | tee -a logs.txt curl -G https://lemnoslife.com/CENSORED/notify.php --data-urlencode "message=$MESSAGE" -d key=$KEY ``` </details> one second and exponential delays do not seem appropriate.

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Reference: Benjamin_Loison/linux#69