Last day I had competition: setup TeamCity project with git submodules from github.
I quickly found this link with some solution, but I didn't found any tomcat files around TeamCity installation folder on my server.
Then I poked around, dig into
TeamCity/conf folder and I found catalina.properties file. I just written down this lines to catalina.properties:
proxyset=true http.proxyHost=myproxyserver.mydomain.com http.proxyPort=8080 http.nonProxyHosts="mydomain.com" https.proxyHost=myproxyserver.mydomain.com https.proxyPort=8080 https.nonProxyHosts="mydomain.com"
and now test git connection to GitHub in TeamCity works!