When using LocalForward or DynamicForward sometimes the endpoint does no
longer exist but I need to find out *which* endpoint exactly. For example:
$ ssh -D 1234 server.example.net
On the client, maybe in another terminal:
$ curl --socks5-hostname localhost:1234 http://does-not-exist.local
curl: (97) connection to proxy closed
As expected. But on the server (OpenSSH 8.4), the following is printed on
stderr:
channel 5: open failed: connect failed: Name or service not known
OK, now in this simple case I know that this is about
"does-not-exist.local", which I know does not exist. But with multiple
LocalForward directives specified, and with DynamicForward active too (the
client is dictating the destination here), I'd like to find out *which*
name cannot be resolved ("Name or service not known") or contacted.
Current scenario: my web browser is using localhost:1234 as its SOCKS
proxy and I have some tab open which may send requests to some
not-existing (or non-resolving) name and my SSH session is semi-flooded
with these messages above. Why mildly annoying, I'm curious which browser
tab to close :-)
I tried to strace(1) the sshd process on the remote side to find out, but
I'm not allowed to ptrace() my own sshd process :(
Does anybody have an idea how to find out the culprit here?
Ideas welcome.
Thanks,
Christian.
--
BOFH excuse #190:
Proprietary Information.