Alain D D Williams <a...@phcomp.co.uk> wrote: > On Wed, Jan 22, 2025 at 01:29:41PM +0000, Chris Green wrote: > > I have a remote headless system (running bullseye, will be updating to > > bookworm when I'm next there) that can connect to some systems using > > ssh but not to others (to which I can connect from everywhere else). > > > > It also can't ping the systems which it can't connect ssh to. > > > > I can't see any pattern in the systems to which it can connect or > > those which it can't connect to. It's connected via 4G so it's > > CGNATted. I connect to it (using ssh) via a remote ssh tunnel that it > > sets up when booted. > > > > It gets the correct IP address for all 'my' systems that run an ssh > > server and I can cannect to all these systems from my home desktop and > > laptop machines using ssh. > > > > Does anyone have any ideas on how to diagnose its failure to connect > > to all of 'my' systems. > > How many network interfaces have you got ? I suspect one (+ loopback). > > What do you get when you run traceroute to something that you cannot connect > to ? > Very little, I tried that. I get a trace to two local (non routable, 192.168..) addresses and then just stars.
> What are your routing tables ? > > Do you have a firewall ? > > Is it an IPv4/IPv6 thing ? So that you can connect to systems over IPv4 but > not > IPv6 ? > I did wonder that, but no, I can connect to some places with both IPV4 and IPV6 addresses but not others. -- Chris Green ยท
