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List all IP addresses connected to your Server
Below is an Unix command to list all the IP addresses connected to your server on port 80. Output – Total connections by IP, from highest to lowest. Note This command is useful to detect if your server is under attack, and null route those IPs. Read this null route attacker IP story. Let break above lengthy command into pieces : 1. netstat -tn 2>/dev/null Uses netstat to list all network connections, ins and outs. -n – Display numeric only, don’t resolve into name. -t – Display only TCP connections. Output 2>/dev/null Redirect all unwanted output to /dev/null, a special place to absorb all output and clear it. 2. grep…
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How to Get Primary IP on Linux
Use grep to filter IP address from ifconfig: ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1' Or with sed: ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p' If you are only interested in certain interfaces, wlan0, eth0, etc. then: ifconfig wlan0 | ... You can alias the command in your .bashrc to create your own command called myip for instance. alias myip="ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'" A much simpler way is hostname -I (hostname -i for older versions of hostname but see comments). However, this is on Linux only.
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How To Find All Files Contain Specific Text
Do the following: grep -rnw '/path/to/somewhere/' -e 'pattern' -r or -R is recursive, -n is line number, and -w stands for match the whole word. -l (lower-case L) can be added to just give the file name of matching files. Along with these, --exclude, --include, --exclude-dir flags could be used for efficient searching: This will only search through those files which have .c or .h extensions: grep --include=\*.{c,h} -rnw '/path/to/somewhere/' -e "pattern" This will exclude searching all the files ending with .o extension: grep --exclude=*.o -rnw '/path/to/somewhere/' -e "pattern" For directories it’s possible to exclude a particular directory(ies) through --exclude-dir parameter. For example, this will exclude the dirs dir1/, dir2/…
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Linux : Check Listening Port on Service
Open your terminal and type as lsof -i :8000 that command will list you the application used by that port with PID. (If no results run via sudo since your might have no permission to certain processes.) For example, with port 8000 (python3 -m http.server): $ lsof -i :8000 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME python3 3269 user 3u IPv4 1783216 0t0 TCP *:8000 (LISTEN) And port 22 (SSH): $ sudo lsof -i :22 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME sshd 998 root 3u IPv4 1442116 0t0 TCP *:ssh (LISTEN) sshd 998 root 4u IPv6 1442118 0t0 TCP *:ssh (LISTEN) Hope that helps.