TCP traffic doesnt route

[Taro-AB81]

Hi All,

I have a device that need to SSH at the other end. inbetween a CISCO router. Inside router i have done the NAT. All work fine and I can do ICMP ping from my end to device. It NAT inside CISCO router and reach the device then return the reply.

Issue is if i try to SSH or access via any other port it doesnt work. So i captured the traffic inside router. both outside and inside traffic. I realize if i send any UDP traffic, it goes to Router, NAT then send out of router. ( make sense why ICMP work)

But if I use TCP traffic then once reached router, it doesnt goes out. may be TCP traffic doesn't hit the nat table. Appreciate your expertise.

[dmcdonald]

often this is a physical issue.  UDP packets are often smaller than TCP segments.  I'd look for duplex mismatch or other physical issues first, then check nat more carefully to see if you have asymmetric traffic or some backdoor route.