How to copy a local file while logged into a SSH session within Linux (ubuntu)

OK, so I found the root cause of my issue and it's so simple I'm slightly embarrassed: conflicting network IPs. It was indeed a network issue as I had surmised, however, it was not as complicated as I was making it.

Since I am using bridged networking, the VM shows up in the DHCP clients table along with all the other machines on the network. If any one of those other machines grabs my VM's IP from DHCP (say before I boot my VM up for the day) it will cause a conflict whenever my VM comes on line and might cause my VM to stop responding to SSH. This explains why when I was using the VirtualBox terminal, I did not experience any problems at all.

I'm not exactly sure how most routers handle IP conflicts, but it seems that, whichever machine is last to have network activity gets precedence. So when I bounced the networking on my machine it was fine until whichever machine was sharing the IP decided to engage in networking activity and then BOOM ... my connection would hang.

I reset my VM's static network IP to be quite high in our range, so hopefully that will keep it clear of any IP conflicts with my co-workers' machines.

To send a file:

cat file | ssh ajw@dogmatix "cat > remote"

Or:

ssh ajw@dogmatix "cat > remote" < file

To receive a file:

ssh ajw@dogmatix "cat remote" > copy