Description of problem: I haven't been able to get into the Red Hat vpn using vpnc-0.4.0-1.fc7. The vpnc executable from vpnc-0.3.3-13.fc6 works like a charm. I run as root vpnc --ifname tun0 /name/of/config.file where config.file contains stuff such as: IPsec gateway <snipped> (the RDU gateway) IPsec ID <snipped> IPsec secret <snipped> Xauth username <snipped> # Rekeying interval 7200 Version-Release number of selected component (if applicable): vpnc-0.4.0-1.fc7.x86_64 How reproducible: Every time Steps to Reproduce: 1.Start vpnc with --no-detach, as above 2.Enter the password Actual results: Shortly after displaying the banner, it quits. Expected results: Not quitting. Additional info: It's behind NAT, which works fine with the older release. Apparently it sends a packet after S7.10, and receives a response to the effect that it should quit, so it prints S8, logs "connection terminated by peer" and quits.
It seems like the x86_64 compilation bug is back. Can you try to recompile the src.rpm without -fstack-protector whether it helps?
Yes. Compiling without -fstack-protector on x86_64 makes this bug vanish (poof!).
It was caused by a bug in vpnc. It was overwriting a value on stack because of wrong sizeof() call. The -fstack-protector caused reordering the values on the stack so an important value was overwritten without the option the overwrite was harmless so the code worked.