termshark doesn't give sufficient error for non-root users

[sagis-tikal]

When termshark is executed with no parameters and not as root it will print the following error:
"INFO[0004] tshark: Couldn't run /usr/bin/dumpcap in child process: Permission denied"

Tried to use both the pre-compiled version and to compile it using the with GO111MODULE=on
termshark version: 1.0.0
tshark version: TShark (Wireshark) 3.0.1 (Git)
OS version: 4.19.35-1-MANJARO (inside of a VirtualBox VM)

[gcla]

Thanks for the report, I'll try to improve that.

[pocc]

termshark is relaying the permissions issue that dumpcap ran into. termshark could ask for sudo privileges, but tshark/dumpcap fail on permission error, so termshark should mimic behavior.

@sagis-tikal This is an issue if capturing with command dumpcap does not produce this error but capturing with termshark does. Otherwise, please close this issue.

[mr-sour]

I ran into this to I got "Could not find network interface vcan0" but the problem was my permissions a more descriptive error or just adding the age ol "Are you root?" to the existing error message would be an improvement. running with sudo fixed it.

[pocc]

Permission Errors

This is tshark's permission error:

tshark: Couldn't run /usr/bin/dumpcap in child process: Permission denied

Checking in an Ubuntu VM, this is what I get for termshark without sudo:

Cannot capture on interface ciscodump: fork/exec /usr/bin/dumpcap: permission denied (exit code -1)
See https://wiki.wireshark.org/CaptureSetup/CapturePrivileges for more info.

Which is plenty informative, and better than tshark's error message.

Need Info

Can users experiencing this issue please post

• tshark -v
• the error text that termshark gives without sudo?

[gcla]

I think I have introduced a regression in termshark v2. I'll look at making this more informative.

[gcla]

I added a more useful comment - to run a setcap command, and as @mr-sour suggested, the good old-fashioned "use root" ;-)

If you want to try it, the latest can be installed with

go get github.com/gcla/termshark/v2/cmd/termshark@master

[gcla]

I added this link too: https://termshark.io/no-root

I'll close this issue now.