CN= [ req_ext ] subjectAltName = @alt_names [ alt_names ] DNS.1 = DNS.2 = DNS.3 = EOF )) ``` ###### List available EC curves ```bash openssl ecparam -list_curves ``` ###### Generate ECDSA private key ```bash # _curve: prime256v1, secp521r1, secp384r1 ( _fd="private.key" ; _curve="prime256v1" ; \ openssl ecparam -out ${_fd} -name ${_curve} -genkey ) # _curve: X25519 ( _fd="private.key" ; _curve="x25519" ; \ openssl genpkey -algorithm ${_curve} -out ${_fd} ) ``` ###### Print ECDSA private and public keys ```bash ( _fd="private.key" ; \ openssl ec -in ${_fd} -noout -text ) # For x25519 only extracting public key ( _fd="private.key" ; _fd_pub="public.key" ; \ openssl pkey -in ${_fd} -pubout -out ${_fd_pub} ) ``` ###### Generate private key with csr (ECC) ```bash # _curve: prime256v1, secp521r1, secp384r1 ( _fd="domain.com.key" ; _fd_csr="domain.com.csr" ; _curve="prime256v1" ; openssl ecparam -out ${_fd} -name ${_curve} -genkey ; openssl req -new -key ${_fd} -out ${_fd_csr} -sha256 ) ``` ###### Convert DER to PEM ```bash ( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \ openssl x509 -in ${_fd_der} -inform der -outform pem -out ${_fd_pem} ) ``` ###### Convert PEM to DER ```bash ( _fd_der="cert.crt" ; _fd_pem="cert.pem" ; \ openssl x509 -in ${_fd_pem} -outform der -out ${_fd_der} ) ``` ###### Checking whether the private key and the certificate match ```bash (openssl rsa -noout -modulus -in private.key | openssl md5 ; openssl x509 -noout -modulus -in certificate.crt | openssl md5) | uniq ``` ___ ##### Tool: [secure-delete](https://wiki.archlinux.org/index.php/Securely_wipe_disk) ###### Secure delete with shred ```bash shred -vfuz -n 10 file shred --verbose --random-source=/dev/urandom -n 1 /dev/sda ``` ###### Secure delete with scrub ```bash scrub -p dod /dev/sda scrub -p dod -r file ``` ###### Secure delete with badblocks ```bash badblocks -s -w -t random -v /dev/sda badblocks -c 10240 -s -w -t random -v /dev/sda ``` ###### Secure delete with secure-delete ```bash srm -vz /tmp/file sfill -vz /local sdmem -v swapoff /dev/sda5 && sswap -vz /dev/sda5 ``` ___ ##### Tool: [dd](https://en.wikipedia.org/wiki/Dd_(Unix)) ###### Show dd status every so often ```bash dd status=progress watch --interval 5 killall -USR1 dd ``` ###### Redirect output to a file with dd ```bash echo "string" | dd of=filename ``` HTTP/HTTPS ##### Tool: [curl](https://curl.haxx.se) ```bash curl -Iks https://www.google.com ``` * `-I` - show response headers only * `-k` - insecure connection when using ssl * `-s` - silent mode (not display body) ```bash curl -Iks --location -X GET -A "x-agent" https://www.google.com ``` * `--location` - follow redirects * `-X` - set method * `-A` - set user-agent ```bash curl -Iks --location -X GET -A "x-agent" --proxy http://127.0.0.1:16379 https://www.google.com ``` * `--proxy [socks5://|http://]` - set proxy server ###### Check DNS and HTTP trace with headers for specific domains ```bash ### Set domains and external dns servers. _domain_list=(google.com) ; _dns_list=("8.8.8.8" "1.1.1.1") for _domain in "${_domain_list[@]}" ; do printf '=%.0s' {1..48} echo printf "[\\e[1;32m+\\e[m] resolve: %s\\n" "$_domain" for _dns in "${_dns_list[@]}" ; do # Resolve domain. host "${_domain}" "${_dns}" echo done for _proto in http https ; do printf "[\\e[1;32m+\\e[m] trace + headers: %s://%s\\n" "$_proto" "$_domain" # Get trace and http headers. curl -Iks -A "x-agent" --location "${_proto}://${_domain}" echo done done unset _domain_list _dns_list ``` ___ ##### Tool: [httpie](https://httpie.org/) ```bash http -p Hh https://www.google.com ``` * `-p` - print request and response headers * `H` - request headers * `B` - request body * `h` - response headers * `b` - response body ```bash http -p Hh --follow --max-redirects 5 --verify no https://www.google.com ``` * `-F, --follow` - follow redirects * `--max-redirects N` - maximum for `--follow` * `--verify no` - skip SSL verification ```bash http -p Hh --follow --max-redirects 5 --verify no --proxy http:http://127.0.0.1:16379 https://www.google.com ``` * `--proxy [http:]` - set proxy server Network ##### Tool: [ssh](https://www.openssh.com/) ###### Escape Sequence ``` # Supported escape sequences: ~. - terminate connection (and any multiplexed sessions) ~B - send a BREAK to the remote system ~C - open a command line ~R - Request rekey (SSH protocol 2 only) ~^Z - suspend ssh ~# - list forwarded connections ~& - background ssh (when waiting for connections to terminate) ~? - this message ~~ - send the escape character by typing it twice ``` ###### Compare a remote file with a local file ```bash ssh user@host cat /path/to/remotefile | diff /path/to/localfile - ``` ###### SSH connection through host in the middle ```bash ssh -t reachable_host ssh unreachable_host ``` ###### Run command over ssh on remote host ```bash cat > cmd.txt << __EOF__ cat /etc/hosts __EOF__ ssh host -l user $(&1 | tee -a "${_sesdir}/$(date +%Y%m%d).log" } # Alias: alias ssh='_ssh_sesslog' ``` ###### Using Keychain for SSH logins ```bash ### Delete all of ssh-agent's keys. function _scl() { /usr/bin/keychain --clear } ### Add key to keychain. function _scg() { /usr/bin/keychain /path/to/private-key source "$HOME/.keychain/$HOSTNAME-sh" } ``` ###### SSH login without processing any login scripts ```bash ssh -tt user@host bash ``` ###### SSH local port forwarding Example 1: ```bash # Forwarding our local 2250 port to nmap.org:443 from localhost through localhost host1> ssh -L 2250:nmap.org:443 localhost # Connect to the service: host1> curl -Iks --location -X GET https://localhost:2250 ``` Example 2: ```bash # Forwarding our local 9051 port to db.d.x:5432 from localhost through node.d.y host1> ssh -nNT -L 9051:db.d.x:5432 node.d.y # Connect to the service: host1> psql -U db_user -d db_dev -p 9051 -h localhost ``` * `-n` - redirects stdin from `/dev/null` * `-N` - do not execute a remote command * `-T` - disable pseudo-terminal allocation ###### SSH remote port forwarding ```bash # Forwarding our local 9051 port to db.d.x:5432 from host2 through node.d.y host1> ssh -nNT -R 9051:db.d.x:5432 node.d.y # Connect to the service: host2> psql -U postgres -d postgres -p 8000 -h localhost ``` ___ ##### Tool: [linux-dev](https://www.tldp.org/LDP/abs/html/devref1.html) ###### Testing remote connection to port ```bash timeout 1 bash -c "//" >/dev/null 2>&1 ; echo $? ``` * `` - set remote host * `` - set destination port ###### Read and write to TCP or UDP sockets with common bash tools ```bash exec 5<>/dev/tcp//; cat <&5 & cat >&5; exec 5>&- ``` ___ ##### Tool: [tcpdump](http://www.tcpdump.org/) ###### Filter incoming (on interface) traffic (specific ) ```bash tcpdump -ne -i eth0 -Q in host 192.168.252.1 and port 443 ``` * `-n` - don't convert addresses (`-nn` will not resolve hostnames or ports) * `-e` - print the link-level headers * `-i [iface|any]` - set interface * `-Q|-D [in|out|inout]` - choose send/receive direction (`-D` - for old tcpdump versions) * `host [ip|hostname]` - set host, also `[host not]` * `[and|or]` - set logic * `port [1-65535]` - set port number, also `[port not]` ###### Filter incoming (on interface) traffic (specific ) and write to a file ```bash tcpdump -ne -i eth0 -Q in host 192.168.252.1 and port 443 -c 5 -w tcpdump.pcap ``` * `-c [num]` - capture only num number of packets * `-w [filename]` - write packets to file, `-r [filename]` - reading from file ###### Capture all ICMP packets ```bash tcpdump -nei eth0 icmp ``` ###### Check protocol used (TCP or UDP) for service ```bash tcpdump -nei eth0 tcp port 22 -vv -X | egrep "TCP|UDP" ``` ###### Display ASCII text (to parse the output using grep or other) ```bash tcpdump -i eth0 -A -s0 port 443 ``` ###### Grab everything between two keywords ```bash tcpdump -i eth0 port 80 -X | sed -n -e '/username/,/=ldap/ p' ``` ###### Grab user and pass ever plain http ```bash tcpdump -i eth0 port http -l -A | egrep -i 'pass=|pwd=|log=|login=|user=|username=|pw=|passw=|passwd=|password=|pass:|user:|username:|password:|login:|pass |user ' --color=auto --line-buffered -B20 ``` ###### Extract HTTP User Agent from HTTP request header ```bash tcpdump -ei eth0 -nn -A -s1500 -l | grep "User-Agent:" ``` ###### Capture only HTTP GET and POST packets ```bash tcpdump -ei eth0 -s 0 -A -vv 'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420' or 'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x504f5354' ``` or simply: ```bash tcpdump -ei eth0 -s 0 -v -n -l | egrep -i "POST /|GET /|Host:" ``` ###### Rotate capture files ```bash tcpdump -ei eth0 -w /tmp/capture-%H.pcap -G 3600 -C 200 ``` * `-G ` - pcap will be created every `` seconds * `-C ` - close the current pcap and open a new one if is larger than `` ###### Top hosts by packets ```bash tcpdump -ei enp0s25 -nnn -t -c 200 | cut -f 1,2,3,4 -d '.' | sort | uniq -c | sort -nr | head -n 20 ``` ___ ##### Tool: [tcpick](http://tcpick.sourceforge.net/) ###### Analyse packets in real-time ```bash while true ; do tcpick -a -C -r dump.pcap ; sleep 2 ; clear ; done ``` ___ ##### Tool: [ngrep](http://ngrep.sourceforge.net/usage.html) ```bash ngrep -d eth0 "www.google.com" port 443 ``` * `-d [iface|any]` - set interface * `[domain]` - set hostname * `port [1-65535]` - set port number ```bash ngrep -d eth0 "www.google.com" (host 10.240.20.2) and (port 443) ``` * `(host [ip|hostname])` - filter by ip or hostname * `(port [1-65535])` - filter by port number ```bash ngrep -d eth0 -qt -O ngrep.pcap "www.google.com" port 443 ``` * `-q` - quiet mode (only payloads) * `-t` - added timestamps * `-O [filename]` - save output to file, `-I [filename]` - reading from file ```bash ngrep -d eth0 -qt 'HTTP' 'tcp' ``` * `HTTP` - show http headers * `tcp|udp` - set protocol * `[src|dst] host [ip|hostname]` - set direction for specific node ```bash ngrep -l -q -d eth0 -i "User-Agent: curl*" ``` * `-l` - stdout line buffered * `-i` - case-insensitive search ___ ##### Tool: [hping3](http://www.hping.org/) ```bash hping3 -V -p 80 -s 5050 www.google.com ``` * `-V|--verbose` - verbose mode * `-p|--destport` - set destination port * `-s|--baseport` - set source port * `` - set scan type * `-F|--fin` - set FIN flag, port open if no reply * `-S|--syn` - set SYN flag * `-P|--push` - set PUSH flag * `-A|--ack` - set ACK flag (use when ping is blocked, RST response back if the port is open) * `-U|--urg` - set URG flag * `-Y|--ymas` - set Y unused flag (0x80 - nullscan), port open if no reply * `-M 0 -UPF` - set TCP sequence number and scan type (URG+PUSH+FIN), port open if no reply ```bash hping3 -V -c 1 -1 -C 8 www.google.com ``` * `-c [num]` - packet count * `-1` - set ICMP mode * `-C|--icmptype [icmp-num]` - set icmp type (default icmp-echo = 8) ```bash hping3 -V -c 1000000 -d 120 -S -w 64 -p 80 --flood --rand-source ``` * `--flood` - sent packets as fast as possible (don't show replies) * `--rand-source` - random source address mode * `-d --data` - data size * `-w|--win` - winsize (default 64) ___ ##### Tool: [nmap](https://nmap.org/) ###### Ping scans the network ```bash nmap -sP 192.168.0.0/24 ``` ###### Show only open ports ```bash nmap -F --open 192.168.0.0/24 ``` ###### Full TCP port scan using with service version detection ```bash nmap -p 1-65535 -sV -sS -T4 192.168.0.0/24 ``` ###### Nmap scan and pass output to Nikto ```bash nmap -p80,443 192.168.0.0/24 -oG - | nikto.pl -h - ``` ###### Recon specific ip:service with Nmap NSE scripts stack ```bash # Set variables: _hosts="192.168.250.10" _ports="80,443" # Set Nmap NSE scripts stack: _nmap_nse_scripts="+dns-brute,\ +http-auth-finder,\ +http-chrono,\ +http-cookie-flags,\ +http-cors,\ +http-cross-domain-policy,\ +http-csrf,\ +http-dombased-xss,\ +http-enum,\ +http-errors,\ +http-git,\ +http-grep,\ +http-internal-ip-disclosure,\ +http-jsonp-detection,\ +http-malware-host,\ +http-methods,\ +http-passwd,\ +http-phpself-xss,\ +http-php-version,\ +http-robots.txt,\ +http-sitemap-generator,\ +http-shellshock,\ +http-stored-xss,\ +http-title,\ +http-unsafe-output-escaping,\ +http-useragent-tester,\ +http-vhosts,\ +http-waf-detect,\ +http-waf-fingerprint,\ +http-xssed,\ +traceroute-geolocation.nse,\ +ssl-enum-ciphers,\ +whois-domain,\ +whois-ip" # Set Nmap NSE script params: _nmap_nse_scripts_args="dns-brute.domain=${_hosts},http-cross-domain-policy.domain-lookup=true,http-waf-detect.aggro,http-waf-detect.detectBodyChanges,http-waf-fingerprint.intensive=1" # Perform scan: nmap --script="$_nmap_nse_scripts" --script-args="$_nmap_nse_scripts_args" -p "$_ports" "$_hosts" ``` ___ ##### Tool: [netcat](http://netcat.sourceforge.net/) ```bash nc -kl 5000 ``` * `-l` - listen for an incoming connection * `-k` - listening after client has disconnected * `>filename.out` - save receive data to file (optional) ```bash nc 192.168.0.1 5051 < filename.in ``` * `< filename.in` - send data to remote host ```bash nc -vz 10.240.30.3 5000 ``` * `-v` - verbose output * `-z` - scan for listening daemons ```bash nc -vzu 10.240.30.3 1-65535 ``` * `-u` - scan only udp ports ###### Transfer data file (archive) ```bash server> nc -l 5000 | tar xzvfp - client> tar czvfp - /path/to/dir | nc 10.240.30.3 5000 ``` ###### Launch remote shell ```bash server> nc -l 5000 -e /bin/bash client> nc 10.240.30.3 5000 ``` ###### Simple file server ```bash while true ; do nc -l 5000 | tar -xvf - ; done ``` ###### Simple minimal HTTP Server ```bash while true ; do nc -l -p 1500 -c 'echo -e "HTTP/1.1 200 OK\n\n $(date)"' ; done ``` ###### Simple HTTP Server > Restarts web server after each request - remove `while` condition for only single connection. ```bash cat > index.html << __EOF__

Hello! It's a site.

__EOF__ ``` ```bash server> while : ; do \ (echo -ne "HTTP/1.1 200 OK\r\nContent-Length: $(wc -c /" <"$_sent" & sed "s/^/<= /" <"$_recv" & nc -l -p "$_listen_port" <"$_back" | \ tee "$_sent" | \ nc "$_bk_host" "$_bk_port" | \ tee "$_recv" >"$_back" ``` ```bash server> chmod +x nc-proxy && ./nc-proxy 8080 192.168.252.10:8000 lport: 8080 bk_host: 192.168.252.10 bk_port: 8000 client> http -p h 10.240.30.3:8080 HTTP/1.1 200 OK Accept-Ranges: bytes Cache-Control: max-age=31536000 Content-Length: 2748 Content-Type: text/html; charset=utf-8 Date: Sun, 01 Jul 2018 20:12:08 GMT Last-Modified: Sun, 01 Apr 2018 21:53:37 GMT ``` ###### Create a single-use TCP or UDP proxy ```bash ### TCP -> TCP nc -l -p 2000 -c "nc [ip|hostname] 3000" ### TCP -> UDP nc -l -p 2000 -c "nc -u [ip|hostname] 3000" ### UDP -> UDP nc -l -u -p 2000 -c "nc -u [ip|hostname] 3000" ### UDP -> TCP nc -l -u -p 2000 -c "nc [ip|hostname] 3000" ``` ___ ##### Tool: [gnutls-cli](https://gnutls.org/manual/html_node/gnutls_002dcli-Invocation.html) ###### Testing connection to remote host (with SNI support) ```bash gnutls-cli -p 443 google.com ``` ###### Testing connection to remote host (without SNI support) ```bash gnutls-cli --disable-sni -p 443 google.com ``` ___ ##### Tool: [socat](http://www.dest-unreach.org/socat/doc/socat.html) ###### Testing remote connection to port ```bash socat - TCP4:10.240.30.3:22 ``` * `-` - standard input (STDIO) * `TCP4:` - set tcp4 connection with specific params * `[hostname|ip]` - set hostname/ip * `[1-65535]` - set port number ###### Redirecting TCP-traffic to a UNIX domain socket under Linux ```bash socat TCP-LISTEN:1234,bind=127.0.0.1,reuseaddr,fork,su=nobody,range=127.0.0.0/8 UNIX-CLIENT:/tmp/foo ``` * `TCP-LISTEN:` - set tcp listen with specific params * `[1-65535]` - set port number * `bind=[hostname|ip]` - set bind hostname/ip * `reuseaddr` - allows other sockets to bind to an address * `fork` - keeps the parent process attempting to produce more connections * `su=nobody` - set user * `range=[ip-range]` - ip range * `UNIX-CLIENT:` - communicates with the specified peer socket * `filename` - define socket ___ ##### Tool: [lsof](https://en.wikipedia.org/wiki/Lsof) ###### Show process that use internet connection at the moment ```bash lsof -P -i -n ``` ###### Show process that use specific port number ```bash lsof -i tcp:443 ``` ###### Lists all listening ports together with the PID of the associated process ```bash lsof -Pan -i tcp -i udp ``` ###### List all open ports and their owning executables ```bash lsof -i -P | grep -i "listen" ``` ###### Show all open ports ```bash lsof -Pnl -i ``` ###### Show open ports (LISTEN) ```bash lsof -Pni4 | grep LISTEN | column -t ``` ###### List all files opened by a particular command ```bash lsof -c "process" ``` ###### View user activity per directory ```bash lsof -u username -a +D /etc ``` ###### Show 10 largest open files ```bash lsof / | \ awk '{ if($7 > 1048576) print $7/1048576 "MB" " " $9 " " $1 }' | \ sort -n -u | tail | column -t ``` ___ ##### Tool: [netstat](https://en.wikipedia.org/wiki/Netstat) ###### Graph # of connections for each hosts ```bash netstat -an | \ grep ESTABLISHED | \ awk '{print $5}' | \ awk -F: '{print $1}' | \ grep -v -e '^[[:space:]]*$' | \ sort | uniq -c | \ awk '{ printf("%s\t%s\t",$2,$1) ; for (i = 0; i < $1; i++) {printf("*")}; print "" }' ``` ###### Monitor open connections for specific port including listen, count and sort it per IP ```bash watch "netstat -plan | grep :443 | awk {'print \$5'} | cut -d: -f 1 | sort | uniq -c | sort -nk 1" ``` ___ ##### Tool: [rsync](https://en.wikipedia.org/wiki/Rsync) ###### Rsync remote data as root using sudo ```bash rsync --rsync-path 'sudo rsync' username@hostname:/path/to/dir/ /local/ ``` ___ ##### Tool: [host](https://en.wikipedia.org/wiki/Host_(Unix)) ###### Resolves the domain name (using external dns server) ```bash host google.com 9.9.9.9 ``` ###### Checks the domain administrator (SOA record) ```bash host -t soa google.com 9.9.9.9 ``` ___ ##### Tool: [dig](https://en.wikipedia.org/wiki/Dig_(command)) ###### Resolves the domain name (short output) ```bash dig google.com +short ``` ###### Lookup NS record for specific domain ```bash dig @9.9.9.9 google.com NS ``` ###### Query only answer section ```bash dig google.com +nocomments +noquestion +noauthority +noadditional +nostats ``` ###### Query ALL DNS Records ```bash dig google.com ANY +noall +answer ``` ###### DNS Reverse Look-up ```bash dig -x 172.217.16.14 +short ``` ___ ##### Tool: [certbot](https://certbot.eff.org/) ###### Generate multidomain certificate ```bash certbot certonly -d example.com -d www.example.com ``` ###### Generate wildcard certificate ```bash certbot certonly --manual --preferred-challenges=dns -d example.com -d *.example.com ``` ###### Generate certificate with 4096 bit private key ```bash certbot certonly -d example.com -d www.example.com --rsa-key-size 4096 ``` ___ ##### Tool: [network-other](https://github.com/trimstray/the-book-of-secret-knowledge#tool-network-other) ###### Get all subnets for specific AS (Autonomous system) ```bash AS="AS32934" whois -h whois.radb.net -- "-i origin ${AS}" | \ grep "^route:" | \ cut -d ":" -f2 | \ sed -e 's/^[ \t]//' | \ sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4 | \ cut -d ":" -f2 | \ sed -e 's/^[ \t]/allow /' | \ sed 's/$/;/' | \ sed 's/allow */subnet -> /g' ``` ###### Resolves domain name from dns.google.com with curl and jq ```bash _dname="google.com" ; curl -s "https://dns.google.com/resolve?name=${_dname}&type=A" | jq . ``` Programming ##### Tool: [python](https://www.python.org/) ###### Static HTTP web server ```bash # Python 3.x python3 -m http.server 8000 --bind 127.0.0.1 # Python 2.x python -m SimpleHTTPServer 8000 ``` ###### Static HTTP web server with SSL support ```bash # Python 3.x from http.server import HTTPServer, BaseHTTPRequestHandler import ssl httpd = HTTPServer(('localhost', 4443), BaseHTTPRequestHandler) httpd.socket = ssl.wrap_socket (httpd.socket, keyfile="path/to/key.pem", certfile='path/to/cert.pem', server_side=True) httpd.serve_forever() # Python 2.x import BaseHTTPServer, SimpleHTTPServer import ssl httpd = BaseHTTPServer.HTTPServer(('localhost', 4443), SimpleHTTPServer.SimpleHTTPRequestHandler) httpd.socket = ssl.wrap_socket (httpd.socket, keyfile="path/tp/key.pem", certfile='path/to/cert.pem', server_side=True) httpd.serve_forever() ``` ##### Tool: [awk](http://www.grymoire.com/Unix/Awk.html) ###### Remove duplicate entries in a file without sorting ```bash awk '!x[$0]++' filename ``` ###### Exclude multiple columns using AWK ```bash awk '{$1=$3=""}1' filename ``` ###### Get the last hour of Apache logs ```bash awk '/'$(date -d "1 hours ago" "+%d\\/%b\\/%Y:%H:%M")'/,/'$(date "+%d\\/%b\\/%Y:%H:%M")'/ { print $0 }' /var/log/httpd/access_log ``` ___ ##### Tool: [sed](http://www.grymoire.com/Unix/Sed.html) ###### To print a specific line from a file ```bash sed -n 10p /path/to/file ``` ###### Remove a specific line from a file ```bash sed -i 10d /path/to/file # alternative (BSD): sed -i'' 10d /path/to/file ``` ###### Remove a range of lines from a file ```bash sed -i -re ',d' ``` ___ ##### Tool: [grep](http://www.grymoire.com/Unix/Grep.html) ###### Search for a "pattern" inside all files in the current directory ```bash grep -rn "pattern" grep -RnisI "pattern" * fgrep "pattern" * -R ``` ###### Remove blank lines from a file and save output to new file ```bash grep . filename > newfilename ``` ###### Except multiple patterns ```bash grep -vE '(error|critical|warning)' filename ``` ###### Show data from file without comments ```bash grep -v ^[[:space:]]*# filename ``` ###### Show data from file without comments and new lines ```bash egrep -v '#|^$' filename ```

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