Assuming the jumpbox is a linux box, iptables
can usefully be used on the OUTPUT
chain to restrict which group members can connect to which servers. Something like
iptables -A OUTPUT --gid-owner project1 -p tcp --dport 22 -d ip.of.project1.com -j ACCEPT
iptables -A OUTPUT --gid-owner project1 -j REJECT
iptables -A OUTPUT --gid-owner project2 -p tcp --dport 22 -d ip.of.project2.com -j ACCEPT
iptables -A OUTPUT --gid-owner project2 -j REJECT
which has the handy side-effect of restricting the members of group project1 from doing anything except ssh'ing to project1.com, and similarly for project2 and project2.com. You may also need some corresponding rules in the INPUT
chain, if you restrict INPUT
traffic.