Redirect Androids traffic to Burp

If you want to redirect you Android devices traffic to your Burp instance, you'll just have to use DNAT and MASQUERADING. I was more detailed about this topic in this post. And since the Internet is full of misleading information these are the steps to get it working. A small side remark: Most articles show you how to route the devices traffic through another machine (hosting the Burp instance). In that case one could:

  • force the traffic redirection using arp spoofing
  • connect the Android device to a software (WiFi) access point forwarding everything to the hosting machine

In both cases you'll be using the PREROUTING chain and DNAT on your Burp machine in order to make sure that arriving packets will be forwarded/redirected to Burp's socket. In my case I won't be using PREROUTING since I'll try to redirect all locally generated packets to another host. To be more specific: All outbound traffic (OUTPUT chain) (destinated at a certain port) will be redirected to the Burp machine.

Supposing your Android device (192.168.0.3) and the machine Burp is listening on (192.168.0.2:8080) are in the same WiFi-Network, you may have sth like this:

Let's begin:

Flush iptables NAT table

$ adb shell "iptables -t nat -F"

Redirect HTTP traffic to Burp

$ adb shell "iptables -t nat -A OUTPUT -p tcp --dport 80 -j DNAT --to-destination 192.168.0.2:8080

Redirect HTTPS traffic to Burp

$ adb shell "iptables -t nat -A OUTPUT -p tcp --dport 443 -j DNAT --to-destination 192.168.0.2:8080

Activate Masquerading

$ adb shell "iptables -t nat -A POSTROUTING -p tcp --dport 80 -j MASQUERADE"
$ adb shell "iptables -t nat -A POSTROUTING -p tcp --dport 443 -j MASQUERADE"

That's it. You can test it by making a HTTPS connection to paypal.com:

$ curl -I https://www.paypal.com
curl: (60) SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
More details here: http://curl.haxx.se/docs/sslcerts.html

curl performs SSL certificate verification by default, using a "bundle"
 of Certificate Authority (CA) public keys (CA certs). If the default
 bundle file isn't adequate, you can specify an alternate file
 using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
 the bundle, the certificate verification probably failed due to a
 problem with the certificate (it might be expired, or the name might
 not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
 the -k (or --insecure) option.

This happens because Burp is presenting the client (curl) it's own certificate. If you see that, then you're successfully redirecting your HTTP(s) traffic to Burp.

This should also work for other ports/protocols.


Prev: Import Burp cert into Android
Next: Android remote sniffing using Tcpdump, nc and Wireshark

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Published:
2015-02-19 00:00
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