SSL Handshake fails after clienthello

Question

EDIT: I\'ll leave this as a good example of debugging SSL.

Final analysis: We had a networking issue in which one of our routers was misconfigured for a totally dif

Answer 1

This is old and already answered, but we suffered the same exact issue and the cause was different.

The key was to sniff traffic on our edge router, where we saw ICMP messages to the server (GitHub.com) asking for fragmentation. This was messing the connection, with retransmissions, duplicated ACKs and so.

The ICMP packet had a field, MTU of next hop with a weird value, 1450. The usual value is 1500.

We checked our router and one of the interfaces (an Ethernet tunnel) had this value as MTU, so the router was taking the minumum MTU of all interfaces as next hop. As soon as we removed this interface (it was unused), the SSL handshake started to work again.