Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 1464390

Summary: RFE: AF_VSOCK support in tcpdump
Product: Red Hat Enterprise Linux 7 Reporter: Stefan Hajnoczi <stefanha>
Component: tcpdumpAssignee: Michal Ruprich <mruprich>
Status: CLOSED ERRATA QA Contact: Martin Zelený <mzeleny>
Severity: medium Docs Contact: Jiri Herrmann <jherrman>
Priority: medium    
Version: 7.5CC: areis, chayang, dschoenb, jherrman, juzhang, kdreyer, ksrot, lmiksik, michen, mruprich, msehnout, msekleta, mtessun, mzeleny, pasik, stefanha, thozza, virt-bugs, xfu
Target Milestone: rcKeywords: FutureFeature
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: tcpdump-4.9.0-6.el7 Doc Type: Release Note
Doc Text:
*tcpdump* can now analyze *virtio* traffic The *tcpdump* utility now supports the *virtio-vsock* communication device. This makes it possible for *tcpdump* to filter and analyze virtio communication between a hypervisor and a guest virtual machine.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2018-04-10 11:06:22 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1464362, 1470219    
Bug Blocks: 1363787, 1465928    
Attachments:
Description Flags
pcap file for testing none

Description Stefan Hajnoczi 2017-06-23 10:19:43 UTC 
KVM is adding AF_VSOCK support for host<->guest communication.  See related bz#1464362 for the libpcap prerequisite.

The AF_VSOCK address family offers SOCK_STREAM semantics similar to TCP.  It does not use Ethernet/IP/TCP.  For details see:
http://wiki.qemu.org/Features/VirtioVsock

I am working upstream to add AF_VSOCK packet capture to tcpdump so that users can troubleshoot and analyze guest<->host traffic.  The AF_VSOCK packet capture format is described here:
http://lists.sandelman.ca/pipermail/tcpdump-workers/2017-May/000772.html

Once the feature lands upstream it will be possible to backport it to RHEL.
Comment 3 Stefan Hajnoczi 2017-07-12 14:14:04 UTC 
Patches posted upstream:
https://github.com/the-tcpdump-group/tcpdump/pull/612
Comment 13 Martin Sehnoutka 2017-08-16 09:56:29 UTC 
Hello,

could you please attach a testing pcap file?
Comment 15 Stefan Hajnoczi 2017-08-17 16:03:21 UTC 
Created attachment 1314768 [details]
pcap file for testing

I have attached a pcapng file.  The expected output is:

  $ tcpdump -r wireshark_vsockmon0_20170713133043_VheF4m.pcapng
  13:31:11.261679 VIRTIO 3.1024 > 2.1234 CONNECT, length 76
  13:31:11.261740 VIRTIO 2.1234 > 3.1024 CONNECT, length 76
  13:31:12.552718 VIRTIO 3.1024 > 2.1234 PAYLOAD, length 82
  13:31:12.552854 VIRTIO 2.1234 > 3.1024 CONTROL, length 76
  13:31:13.817848 VIRTIO 3.1024 > 2.1234 PAYLOAD, length 82
  13:31:13.817897 VIRTIO 2.1234 > 3.1024 CONTROL, length 76
  13:31:16.939624 VIRTIO 2.1234 > 3.1024 PAYLOAD, length 83
  13:31:16.947538 VIRTIO 3.1024 > 2.1234 CONTROL, length 76
  13:31:17.368933 VIRTIO 2.1234 > 3.1024 DISCONNECT, length 76
  13:31:17.377004 VIRTIO 3.1024 > 2.1234 DISCONNECT, length 76
Comment 16 Martin Sehnoutka 2017-08-23 13:04:10 UTC 
Thanks, it works now.
Comment 21 Stefan Hajnoczi 2017-10-02 15:07:50 UTC 
Hi Michal,
tcpdump-4.9.0-6 doesn't work for me.  I get the same error you reported.

Martin: Was tcpdump-4.9.0-6 built against a libpcap-devel package that defines DLT_VSOCK?

++++ b/print.c
+@@ -220,6 +220,9 @@ static const struct printer printers[] = {
+ #ifdef DLT_PPP_SERIAL
+ 	{ ppp_hdlc_if_print,	DLT_PPP_SERIAL },
+ #endif
++#ifdef DLT_VSOCK
++	{ vsock_print,		DLT_VSOCK },
++#endif

Also, please note that the vsock code has not been merged into tcpdump.git upstream yet.  I have pinged the maintainers to review/merge it.
Comment 32 Michal Ruprich 2017-12-12 12:27:34 UTC 
Hi Jiri,

yes this looks good.

Thanks.
Comment 33 FuXiangChun 2017-12-20 04:34:26 UTC 
Kvm QE tried to test this bug with the fixed tcpdump version tcpdump-4.9.2-3.el7.x86. This is test result[1], It maybe be helpful.

[1]
https://bugzilla.redhat.com/show_bug.cgi?id=1464362#c21
Comment 34 Martin Zelený 2018-01-05 13:05:10 UTC 
Successfully verified by Case Runs #16499806 (rhel-7) and #16499841 (rhel-alt-7) of TC#561269 - /CoreOS/tcpdump/Sanity/AF_VSOCK-support

:: [   LOG    ] :: Test reading pcap-ng file with tcpdump
:: [  BEGIN   ] :: VSOCK should be supported :: actually running 'tcpdump -r vsock.pcapng'
13:31:11.261679 VIRTIO 3.1024 > 2.1234 CONNECT, length 76
13:31:11.261740 VIRTIO 2.1234 > 3.1024 CONNECT, length 76
13:31:12.552718 VIRTIO 3.1024 > 2.1234 PAYLOAD, length 82
13:31:12.552854 VIRTIO 2.1234 > 3.1024 CONTROL, length 76
13:31:13.817848 VIRTIO 3.1024 > 2.1234 PAYLOAD, length 82
13:31:13.817897 VIRTIO 2.1234 > 3.1024 CONTROL, length 76
13:31:16.939624 VIRTIO 2.1234 > 3.1024 PAYLOAD, length 83
13:31:16.947538 VIRTIO 3.1024 > 2.1234 CONTROL, length 76
13:31:17.368933 VIRTIO 2.1234 > 3.1024 DISCONNECT, length 76
13:31:17.377004 VIRTIO 3.1024 > 2.1234 DISCONNECT, length 76
reading from file vsock.pcapng, link-type VSOCK (Linux vsock)
:: [   PASS   ] :: VSOCK should be supported (Expected 0, got 0)
:: [   PASS   ] :: File '/var/tmp/rlRun_LOG.SclaGPOw' should contain 'VIRTIO'
Comment 37 errata-xmlrpc 2018-04-10 11:06:22 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2018:0705