We'll use this to set granular capabilities on Wireshark's dumpcap executable. Enabling Non-root Capture Step 1: Install setcapįirst, we'll need to install the setcap executable if it hasn't been already. These capabilities are assigned using the setcap utility. CAP_NET_RAW - Permit use of RAW and PACKET sockets.ĬAP_NET_ADMIN allows us to set an interface to promiscuous mode, and CAP_NET_RAW permits raw access to an interface for capturing directly off the wire.CAP_NET_ADMIN - Allow various network-related operations (e.g., setting privileged socket options, enabling multicasting, interface configuration, modifying routing tables).For sniffing, we're interested in two specifically: The manual goes on to list over two dozen distinct POSIX capabilities which individual executables may be granted. Starting with kernel 2.2, Linux divides the privileges traditionally associated with superuser into distinct units, known as capabilities, which can be independently enabled and disabled.
Privileged processes bypass all kernel permission checks, while unprivileged processes are subject to full permission checking based on the process's credentials (usually: effective UID, effective GID, and supplementary group list).
What are filesystem capabilities? From the man page:įor the purpose of performing permission checks, traditional Unix implementations distinguish two categories of processes: privileged processes (whose effective user ID is 0, referred to as superuser or root), and unprivileged processes (whose effective UID is non-zero). In this article, we'll walk through putting this idea into practice on an Ubuntu 9.10 machine, and include a bit more detail behind the system commands. The lead developer of Wireshark, Gerald Combs, points out some that Linux distributions are beginning to implement Linux filesystem capabilities for raw network access. But if we shouldn't run Wireshark with root privileges, how are we to capture packets? Indeed, due to the complexity and sheer number of its many protocol dissectors, Wireshark is inherently vulnerable to malformed traffic (accidental or otherwise), which may result in denial of service conditions or possibly arbitrary code execution. WIRESHARK CONTAINS OVER ONE POINT FIVE MILLION LINES OF SOURCE CODE. As an older Gentoo Linux ebuild of Wireshark warns:
Unfortunately, this often prompts people to simply run Wireshark as root - a bad idea. This is because, by default, raw access to network interfaces (e.g. Many network engineers become dismayed the first time they run Wireshark on a Linux machine and find that they don't have access to any network interfaces. For Windows users, there is some good info in the Wireshark wiki. This article focuses on Linux and some UNIXes.
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