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curl

What Where
Official Page https://curl.se/
Source https://github.com/curl/curl
Download https://github.com/curl/curl/releases
Docker https://hub.docker.com/r/curlimages/curl
Docs https://everything.curl.dev or https://curl.se/docs/manpage.html
Book https://curl.se/docs/
Windows scoop install curl
Ubuntu sudo apt -y install curl

Downloading Files

Simple download

curl -O https://example.com/file.zip

Download with output filename

curl -o myfile.zip https://example.com/file.zip

Use -L to follow redirects:

curl -L https://example.com

Authentication

Example of using curl with basic auth credentials

curl -u username:password staging.example.com

Send Mail

Please note: Gmail no longer supports "less secure apps." Use App Passwords instead.

curl --ssl-reqd --url 'smtps://smtp.gmail.com:465' \
--user '[email protected]:app_password' \
--mail-from '[email protected]' \
--mail-rcpt '[email protected]' \
--upload-file mail.txt

mail.txt file contents:

From: "User Name" <[email protected]>
To: "John Smith" <[email protected]>
Subject: This is a test

Hi John,
I’m sending this mail with curl thru my gmail account.
Bye!

Use --netrc-file instead of credentials in curl command for better security.

Example:

curl --netrc-file ~/.netrc staging.example.com

machine staging.example.com
login username
password password

WebDAV

Create directories on WebDAV:

curl -X MKCOL 'http://your.server/uploads/nested_folder1' --user 'name:pwd'

Upload a file via WebDAV:

curl -T file.txt 'http://your.server/uploads/file.txt' --user 'username:password'

Upload all files in folder (directories must exist):

cd local_folder_to_upload && find . -type f -exec curl -T {} 'http://your.server/uploads/{}' --user 'username:password' \;

Random Examples

check netowrk range

Example to check /24 range in "abuseipdb.com" for the last 3 days

DAYS=3
curl -s -G "https://api.abuseipdb.com/api/v2/check-block" \
  --data-urlencode "network=123.123.123.1/24" \
  -d "maxAgeInDays=$DAYS" \
  -H "Key: apikeyfromabuseipdb.com" \
  -H "Accept: application/json" \
  | jq '.data.reportedAddress'

If you dont have jq installed:

  • ubuntu: sudo apt install jq
  • windows: scoop install jq

Inspect headers

If you want to inspect the headers of a response from some endpoint include the -I flag and curl will return just the headers.

curl -I localhost:3000/posts

or a verbose setting:

curl -v localhost:3000/posts

Request JSON

Query a website e.g. request a json response from cloudflare-dns.com on TXT records of the domain 0xfab1.net

curl -s -H 'accept: application/dns-json' 'https://cloudflare-dns.com/dns-query?name=0xfab1.net&type=TXT'

Send JSON

This command sends a POST request with JSON data.

curl -X POST https://api.example.com/posts \
-H 'Content-Type: application/json' \
-d '{"title":"Hello","body":"Curl"}'

Timing

This command measures the performance of a request.

It shows:

  • DNS lookup time (time_namelookup)
  • TCP connection time (time_connect)
  • total request duration (time_total)

The response body is ignored (-o /dev/null).

curl -w "@-" -o /dev/null -s "https://example.com" <<'EOF'
time_namelookup: %{time_namelookup}\n
time_connect: %{time_connect}\n
time_total: %{time_total}\n
EOF

Using a proxy

Route the request through a proxy server (http://proxyserver:port). This is useful for debugging, bypassing restrictions, or accessing internal networks.

curl -x http://proxyserver:port https://example.com

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