Agent pod failed

Hi Team,

I have installed version 0.1.1

```
kubectl debug --version
debug version v0.0.0-master+$Format:%h$
```

It failed to debug my pods, then I checked agent-pod, it didn't run successfully. The following is its status

```
oc get pods -n default
NAME READY STATUS RESTARTS AGE
debug-agent-pod-563e0614-4b0a-11eb-be05-dca904978b2f 0/1 ImagePullBackOff 0 44m
debug-agent-pod-5dc047e6-4b0d-11eb-9bc4-dca904978b2f 0/1 PodFitsHostPorts 0 22m
debug-agent-pod-a6c36144-4b0d-11eb-b6a7-dca904978b2f 0/1 PodFitsHostPorts 0 20m
```
Could you let me know:
(1) Failed to Pulling image "aylei/debug-agent:latest", how to fix it? Or What is the credential for pulling down image?
(2) How to fix PodFitsHostPorts?

In addition, the below is my configuration:

```
# debug agent listening port(outside container)
# default to 10027
agentPort: 10027

# whether using agentless mode
# default to true
agentless: true
# namespace of debug-agent pod, used in agentless mode
# default to 'default'
agentPodNamespace: default
# prefix of debug-agent pod, used in agentless mode
# default to 'debug-agent-pod'
agentPodNamePrefix: debug-agent-pod
# image of debug-agent pod, used in agentless mode
# default to 'aylei/debug-agent:latest'
agentImage: aylei/debug-agent:latest

# daemonset name of the debug-agent, used in port-forward
# default to 'debug-agent'
debugAgentDaemonset: debug-agent
# daemonset namespace of the debug-agent, used in port-forwad
# default to 'default'
debugAgentNamespace: kube-system
# whether using port-forward when connecting debug-agent
# default true
portForward: true
# image of the debug container
# default as showed
image: nicolaka/netshoot:latest
# start command of the debug container
# default ['bash']
command:
- '/bin/bash'
- '-l'
# private docker registry auth kuberntes secret
# default registrySecretName is kubectl-debug-registry-secret
# default registrySecretNamespace is default
registrySecretName: my-debug-secret
registrySecretNamespace: debug
# in agentless mode, you can set the agent pod's resource limits/requests:
# default is not set
agentCpuRequests: ""
agentCpuLimits: ""
agentMemoryRequests: ""
agentMemoryLimits: ""
# in fork mode, if you want the copied pod retains the labels of the original pod, you can change this params
# format is []string
# If not set, this parameter is empty by default (Means that any labels of the original pod are not retained, and the labels of the copied pods are empty.)
forkPodRetainLabels: []
# You can disable SSL certificate check when communicating with image registry by
# setting registrySkipTLSVerify to true.
registrySkipTLSVerify: false
# You can set the log level with the verbosity setting
verbosity : 0

```

Start with `kubectl debug --version` and the agent-pod status from `oc get pods -n default`; inspect the `agentImage`, registry secret, `agentPort`, and `portForward` settings shown in the configuration. Reproduce the image-pull and host-port failures, then identify the supported resolution; done means the debug agent starts and `kubectl debug` can debug a pod.

Written by the indexing model from the issue text.