adding wireguard example
This commit is contained in:
parent
862d2c335c
commit
72d2b97463
1
.gitignore
vendored
1
.gitignore
vendored
@ -1 +1,2 @@
|
|||||||
*.tmp
|
*.tmp
|
||||||
|
tmp
|
||||||
|
29
wireguard-bastion/README.md
Normal file
29
wireguard-bastion/README.md
Normal file
@ -0,0 +1,29 @@
|
|||||||
|
# DeTEE WireGuard Example
|
||||||
|
|
||||||
|
This examples shows how WireGuard can be used to create network overlays on top of DeTEE.
|
||||||
|
The example is academic and real world scenarios will require improved setups.
|
||||||
|
|
||||||
|
## Network Diagram
|
||||||
|
|
||||||
|
```mermaid
|
||||||
|
graph LR
|
||||||
|
Laptop[Laptop<br/>local-cali: 10.100.10.10/24<br/>local-vanc: 10.200.20.10/24]
|
||||||
|
CaliBastion[Cali Bastion<br/>Server: 10.100.10.1/24<br/>Client: 10.200.20.21/24]
|
||||||
|
VancBastion[Vanc Bastion<br/>Server: 10.200.20.1/24<br/>Client: 10.100.10.21/24]
|
||||||
|
CaliProtected[Cali Protected<br/>cali: 10.100.10.101/24<br/>vanc: 10.200.20.101/24]
|
||||||
|
VancProtected[Vanc Protected<br/>cali: 10.100.10.201/24<br/>vanc: 10.200.20.201/24]
|
||||||
|
|
||||||
|
Laptop -- "WireGuard" --> CaliBastion
|
||||||
|
Laptop -- "WireGuard" --> VancBastion
|
||||||
|
|
||||||
|
CaliBastion -- "WireGuard" --> CaliProtected
|
||||||
|
CaliBastion -- "WireGuard" --> VancProtected
|
||||||
|
VancBastion -- "WireGuard" --> CaliProtected
|
||||||
|
VancBastion -- "WireGuard" --> VancProtected
|
||||||
|
```
|
||||||
|
|
||||||
|
## Commands
|
||||||
|
|
||||||
|
To create the VMs, run `./create_vms.sh`.
|
||||||
|
|
||||||
|
To deploy WireGuard, run `./deploy.sh`.
|
10
wireguard-bastion/cali-bastion.yaml
Normal file
10
wireguard-bastion/cali-bastion.yaml
Normal file
@ -0,0 +1,10 @@
|
|||||||
|
hostname: cali-bastion
|
||||||
|
hours: 5
|
||||||
|
price: 20000
|
||||||
|
location:
|
||||||
|
region: "California"
|
||||||
|
ipv4: !PublishPorts [ 1337 ]
|
||||||
|
public_ipv6: false
|
||||||
|
vcpus: 2
|
||||||
|
memory_mb: 2000
|
||||||
|
disk_size_gb: 20
|
10
wireguard-bastion/cali-protected.yaml
Normal file
10
wireguard-bastion/cali-protected.yaml
Normal file
@ -0,0 +1,10 @@
|
|||||||
|
hostname: cali-protected
|
||||||
|
hours: 5
|
||||||
|
price: 20000
|
||||||
|
location:
|
||||||
|
region: "California"
|
||||||
|
ipv4: !PublishPorts [ ]
|
||||||
|
public_ipv6: false
|
||||||
|
vcpus: 2
|
||||||
|
memory_mb: 2000
|
||||||
|
disk_size_gb: 20
|
8
wireguard-bastion/create_vms.sh
Executable file
8
wireguard-bastion/create_vms.sh
Executable file
@ -0,0 +1,8 @@
|
|||||||
|
#!/bin/bash
|
||||||
|
set -e
|
||||||
|
export FORMAT=YAML
|
||||||
|
|
||||||
|
detee-cli vm deploy --from-yaml cali-bastion.yaml > tmp/cali-bastion-install.yaml
|
||||||
|
detee-cli vm deploy --from-yaml vanc-bastion.yaml > tmp/vanc-bastion-install.yaml
|
||||||
|
detee-cli vm deploy --from-yaml cali-protected.yaml > tmp/cali-protected-install.yaml
|
||||||
|
detee-cli vm deploy --from-yaml vanc-protected.yaml > tmp/vanc-protected-install.yaml
|
132
wireguard-bastion/deploy.sh
Executable file
132
wireguard-bastion/deploy.sh
Executable file
@ -0,0 +1,132 @@
|
|||||||
|
#!/bin/bash
|
||||||
|
set -e
|
||||||
|
export FORMAT=YAML
|
||||||
|
|
||||||
|
echo GETTING UUIDs
|
||||||
|
cali_bastion_uuid=$(grep uuid tmp/cali-bastion-install.yaml)
|
||||||
|
cali_bastion_uuid=${cali_bastion_uuid#uuid: }
|
||||||
|
vanc_bastion_uuid=$(grep uuid tmp/vanc-bastion-install.yaml)
|
||||||
|
vanc_bastion_uuid=${vanc_bastion_uuid#uuid: }
|
||||||
|
cali_protected_uuid=$(grep uuid tmp/cali-protected-install.yaml)
|
||||||
|
cali_protected_uuid=${cali_protected_uuid#uuid: }
|
||||||
|
vanc_protected_uuid=$(grep uuid tmp/vanc-protected-install.yaml)
|
||||||
|
vanc_protected_uuid=${vanc_protected_uuid#uuid: }
|
||||||
|
|
||||||
|
echo BUILDING SSH COMMANDS
|
||||||
|
key_path=$(grep 'key_path:' tmp/cali-bastion-install.yaml | awk '{ print $2 }')
|
||||||
|
ssh_cali_bastion="ssh -i ${key_path} \
|
||||||
|
-p $(grep port tmp/cali-bastion-install.yaml | cut -d "'" -f2) \
|
||||||
|
root@$(grep ip tmp/cali-bastion-install.yaml | awk '{ print $2 }')"
|
||||||
|
ssh_vanc_bastion="ssh -i ${key_path} \
|
||||||
|
-p $(grep port tmp/vanc-bastion-install.yaml | cut -d "'" -f2) \
|
||||||
|
root@$(grep ip tmp/vanc-bastion-install.yaml | awk '{ print $2 }')"
|
||||||
|
ssh_cali_protected="ssh -i ${key_path} \
|
||||||
|
-p $(grep port tmp/cali-protected-install.yaml | cut -d "'" -f2) \
|
||||||
|
root@$(grep ip tmp/cali-protected-install.yaml | awk '{ print $2 }')"
|
||||||
|
ssh_vanc_protected="ssh -i ${key_path} \
|
||||||
|
-p $(grep port tmp/vanc-protected-install.yaml | cut -d "'" -f2) \
|
||||||
|
root@$(grep ip tmp/vanc-protected-install.yaml | awk '{ print $2 }')"
|
||||||
|
|
||||||
|
echo INSPECTING VMs
|
||||||
|
detee-cli vm inspect $cali_bastion_uuid > tmp/cali-bastion-inspect.yaml
|
||||||
|
detee-cli vm inspect $vanc_bastion_uuid > tmp/vanc-bastion-inspect.yaml
|
||||||
|
detee-cli vm inspect $cali_protected_uuid > tmp/cali-protected-inspect.yaml
|
||||||
|
detee-cli vm inspect $vanc_protected_uuid > tmp/vanc-protected-inspect.yaml
|
||||||
|
|
||||||
|
echo GETTING WIREGUARD IP AND PORTS
|
||||||
|
cali_wg_ip=$(grep 'ip: ' tmp/cali-bastion-install.yaml)
|
||||||
|
cali_wg_ip=${cali_wg_ip#ip: }
|
||||||
|
vanc_wg_ip=$(grep 'ip: ' tmp/vanc-bastion-install.yaml)
|
||||||
|
vanc_wg_ip=${vanc_wg_ip#ip: }
|
||||||
|
cali_wg_port=$(grep exposed_ports -A 2 tmp/cali-bastion-inspect.yaml | tail -1)
|
||||||
|
cali_wg_port=${cali_wg_port#- }
|
||||||
|
vanc_wg_port=$(grep exposed_ports -A 2 tmp/vanc-bastion-inspect.yaml | tail -1)
|
||||||
|
vanc_wg_port=${vanc_wg_port#- }
|
||||||
|
|
||||||
|
echo GENERATING WIREGUARD KEYS
|
||||||
|
wg genkey > tmp/cali_bastion_private.key
|
||||||
|
cat tmp/cali_bastion_private.key | wg pubkey > tmp/cali_bastion_public.key
|
||||||
|
wg genkey > tmp/vanc_bastion_private.key
|
||||||
|
cat tmp/vanc_bastion_private.key | wg pubkey > tmp/vanc_bastion_public.key
|
||||||
|
wg genkey > tmp/cali_protected_private.key
|
||||||
|
cat tmp/cali_protected_private.key | wg pubkey > tmp/cali_protected_public.key
|
||||||
|
wg genkey > tmp/vanc_protected_private.key
|
||||||
|
cat tmp/vanc_protected_private.key | wg pubkey > tmp/vanc_protected_public.key
|
||||||
|
wg genkey > tmp/local_private.key
|
||||||
|
cat tmp/local_private.key | wg pubkey > tmp/local_public.key
|
||||||
|
|
||||||
|
echo PREPARING WIREGUARD CONFIGS
|
||||||
|
cp -r wg_configs tmp/
|
||||||
|
sed -i "s,CALI_BASTION_PRIVATE,$(cat tmp/cali_bastion_private.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,CALI_BASTION_PUBLIC,$(cat tmp/cali_bastion_public.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,VANC_BASTION_PRIVATE,$(cat tmp/vanc_bastion_private.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,VANC_BASTION_PUBLIC,$(cat tmp/vanc_bastion_public.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,CALI_PROTECTED_PRIVATE,$(cat tmp/cali_protected_private.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,CALI_PROTECTED_PUBLIC,$(cat tmp/cali_protected_public.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,VANC_PROTECTED_PRIVATE,$(cat tmp/vanc_protected_private.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,VANC_PROTECTED_PUBLIC,$(cat tmp/vanc_protected_public.key)," tmp/wg_configs/*
|
||||||
|
|
||||||
|
sed -i "s,LOCAL_PRIVATE,$(cat tmp/local_private.key)," tmp/wg_configs/*
|
||||||
|
sed -i "s,LOCAL_PUBLIC,$(cat tmp/local_public.key)," tmp/wg_configs/*
|
||||||
|
|
||||||
|
sed -i "s,VANC_BASTION_IP,${vanc_wg_ip}," tmp/wg_configs/*
|
||||||
|
sed -i "s,CALI_BASTION_IP,${cali_wg_ip}," tmp/wg_configs/*
|
||||||
|
sed -i "s,VANC_BASTION_PORT,${vanc_wg_port}," tmp/wg_configs/*
|
||||||
|
sed -i "s,CALI_BASTION_PORT,${cali_wg_port}," tmp/wg_configs/*
|
||||||
|
|
||||||
|
echo INSTALLING SOFTWARE
|
||||||
|
$ssh_cali_bastion pacman -Syu --noconfirm > tmp/cali_bastion.log 2>&1
|
||||||
|
$ssh_vanc_bastion pacman -Syu --noconfirm > tmp/vanc_bastion.log 2>&1
|
||||||
|
$ssh_cali_bastion pacman -S wireguard-tools --needed --noconfirm > tmp/cali_bastion.log 2>&1
|
||||||
|
$ssh_vanc_bastion pacman -S wireguard-tools --needed --noconfirm > tmp/vanc_bastion.log 2>&1
|
||||||
|
$ssh_cali_bastion sysctl -w net.ipv4.conf.all.forwarding=1
|
||||||
|
$ssh_vanc_bastion sysctl -w net.ipv4.conf.all.forwarding=1
|
||||||
|
|
||||||
|
$ssh_cali_protected pacman -Syu --noconfirm > tmp/vanc_protected.log 2>&1
|
||||||
|
$ssh_vanc_protected pacman -Syu --noconfirm > tmp/vanc_protected.log 2>&1
|
||||||
|
$ssh_cali_protected pacman -S wireguard-tools nginx \
|
||||||
|
--needed --noconfirm > tmp/vanc_protected.log 2>&1
|
||||||
|
$ssh_vanc_protected pacman -S wireguard-tools nginx \
|
||||||
|
--needed --noconfirm > tmp/vanc_protected.log 2>&1
|
||||||
|
$ssh_cali_protected systemctl start nginx
|
||||||
|
$ssh_vanc_protected systemctl start nginx
|
||||||
|
|
||||||
|
echo UPLOADING WIREGUARD CONFIG
|
||||||
|
{
|
||||||
|
cat tmp/wg_configs/cali-bastion-server.conf | $ssh_cali_bastion tee /etc/wireguard/server.conf
|
||||||
|
cat tmp/wg_configs/cali-bastion-client.conf | $ssh_cali_bastion tee /etc/wireguard/vanc.conf
|
||||||
|
cat tmp/wg_configs/vanc-bastion-server.conf | $ssh_vanc_bastion tee /etc/wireguard/server.conf
|
||||||
|
cat tmp/wg_configs/vanc-bastion-client.conf | $ssh_vanc_bastion tee /etc/wireguard/cali.conf
|
||||||
|
cat tmp/wg_configs/cali-protected-cali.conf | $ssh_cali_protected tee /etc/wireguard/cali.conf
|
||||||
|
cat tmp/wg_configs/cali-protected-vanc.conf | $ssh_cali_protected tee /etc/wireguard/vanc.conf
|
||||||
|
cat tmp/wg_configs/vanc-protected-cali.conf | $ssh_vanc_protected tee /etc/wireguard/cali.conf
|
||||||
|
cat tmp/wg_configs/vanc-protected-vanc.conf | $ssh_vanc_protected tee /etc/wireguard/vanc.conf
|
||||||
|
} > /dev/null
|
||||||
|
|
||||||
|
echo STARTING WIREGUARD
|
||||||
|
$ssh_cali_bastion wg-quick up server
|
||||||
|
$ssh_vanc_bastion wg-quick up server
|
||||||
|
$ssh_vanc_bastion wg-quick up cali
|
||||||
|
$ssh_cali_protected wg-quick up cali
|
||||||
|
$ssh_vanc_protected wg-quick up cali
|
||||||
|
$ssh_cali_bastion wg-quick up vanc
|
||||||
|
$ssh_cali_protected wg-quick up vanc
|
||||||
|
$ssh_vanc_protected wg-quick up vanc
|
||||||
|
|
||||||
|
# SETTING UP LOCAL CLIENT
|
||||||
|
if [[ $(whoami) == "root" ]]; then
|
||||||
|
sudo=""
|
||||||
|
else
|
||||||
|
sudo="sudo"
|
||||||
|
fi
|
||||||
|
$sudo cp tmp/wg_configs/local-cali.conf /etc/wireguard/
|
||||||
|
$sudo cp tmp/wg_configs/local-vanc.conf /etc/wireguard/
|
||||||
|
$sudo wg-quick up local-cali
|
||||||
|
$sudo wg-quick up local-vanc
|
||||||
|
|
||||||
|
|
||||||
|
echo To check if VPN works to the protected nodes, try to access a protected service:
|
||||||
|
echo curl http://10.200.20.101
|
||||||
|
echo curl http://10.100.10.101
|
||||||
|
echo curl http://10.100.10.201
|
||||||
|
echo curl http://10.200.20.201
|
10
wireguard-bastion/vanc-bastion.yaml
Normal file
10
wireguard-bastion/vanc-bastion.yaml
Normal file
@ -0,0 +1,10 @@
|
|||||||
|
hostname: vanc-bastion
|
||||||
|
hours: 5
|
||||||
|
price: 20000
|
||||||
|
location:
|
||||||
|
city: "Vancouver"
|
||||||
|
ipv4: !PublishPorts [ 1337 ]
|
||||||
|
public_ipv6: false
|
||||||
|
vcpus: 2
|
||||||
|
memory_mb: 2000
|
||||||
|
disk_size_gb: 20
|
10
wireguard-bastion/vanc-protected.yaml
Normal file
10
wireguard-bastion/vanc-protected.yaml
Normal file
@ -0,0 +1,10 @@
|
|||||||
|
hostname: vanc-protected
|
||||||
|
hours: 5
|
||||||
|
price: 20000
|
||||||
|
location:
|
||||||
|
city: "Vancouver"
|
||||||
|
ipv4: !PublishPorts [ ]
|
||||||
|
public_ipv6: false
|
||||||
|
vcpus: 2
|
||||||
|
memory_mb: 2000
|
||||||
|
disk_size_gb: 20
|
8
wireguard-bastion/wg_configs/cali-bastion-client.conf
Normal file
8
wireguard-bastion/wg_configs/cali-bastion-client.conf
Normal file
@ -0,0 +1,8 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.200.20.21/24
|
||||||
|
PrivateKey = CALI_BASTION_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.0/24
|
||||||
|
Endpoint = VANC_BASTION_IP:VANC_BASTION_PORT
|
20
wireguard-bastion/wg_configs/cali-bastion-server.conf
Normal file
20
wireguard-bastion/wg_configs/cali-bastion-server.conf
Normal file
@ -0,0 +1,20 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.100.10.1/24
|
||||||
|
PrivateKey = CALI_BASTION_PRIVATE
|
||||||
|
ListenPort = 1337
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_PROTECTED_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.101/32
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = VANC_PROTECTED_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.201/32
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = VANC_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.21/32
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = LOCAL_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.10/32
|
9
wireguard-bastion/wg_configs/cali-protected-cali.conf
Normal file
9
wireguard-bastion/wg_configs/cali-protected-cali.conf
Normal file
@ -0,0 +1,9 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.100.10.101/24
|
||||||
|
PrivateKey = CALI_PROTECTED_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.0/24
|
||||||
|
Endpoint = CALI_BASTION_IP:CALI_BASTION_PORT
|
||||||
|
PersistentKeepalive = 25
|
9
wireguard-bastion/wg_configs/cali-protected-vanc.conf
Normal file
9
wireguard-bastion/wg_configs/cali-protected-vanc.conf
Normal file
@ -0,0 +1,9 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.200.20.101/24
|
||||||
|
PrivateKey = CALI_PROTECTED_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = VANC_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.0/24
|
||||||
|
Endpoint = VANC_BASTION_IP:VANC_BASTION_PORT
|
||||||
|
PersistentKeepalive = 25
|
8
wireguard-bastion/wg_configs/local-cali.conf
Normal file
8
wireguard-bastion/wg_configs/local-cali.conf
Normal file
@ -0,0 +1,8 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.100.10.10/24
|
||||||
|
PrivateKey = LOCAL_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.0/24
|
||||||
|
Endpoint = CALI_BASTION_IP:CALI_BASTION_PORT
|
8
wireguard-bastion/wg_configs/local-vanc.conf
Normal file
8
wireguard-bastion/wg_configs/local-vanc.conf
Normal file
@ -0,0 +1,8 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.200.20.10/24
|
||||||
|
PrivateKey = LOCAL_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = VANC_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.0/24
|
||||||
|
Endpoint = VANC_BASTION_IP:VANC_BASTION_PORT
|
8
wireguard-bastion/wg_configs/vanc-bastion-client.conf
Normal file
8
wireguard-bastion/wg_configs/vanc-bastion-client.conf
Normal file
@ -0,0 +1,8 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.100.10.21/24
|
||||||
|
PrivateKey = VANC_BASTION_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.0/24
|
||||||
|
Endpoint = CALI_BASTION_IP:CALI_BASTION_PORT
|
20
wireguard-bastion/wg_configs/vanc-bastion-server.conf
Normal file
20
wireguard-bastion/wg_configs/vanc-bastion-server.conf
Normal file
@ -0,0 +1,20 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.200.20.1/24
|
||||||
|
PrivateKey = VANC_BASTION_PRIVATE
|
||||||
|
ListenPort = 1337
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_PROTECTED_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.101/32
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = VANC_PROTECTED_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.201/32
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.21/32
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = LOCAL_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.10/32
|
9
wireguard-bastion/wg_configs/vanc-protected-cali.conf
Normal file
9
wireguard-bastion/wg_configs/vanc-protected-cali.conf
Normal file
@ -0,0 +1,9 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.100.10.201/24
|
||||||
|
PrivateKey = VANC_PROTECTED_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = CALI_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.100.10.0/24
|
||||||
|
Endpoint = CALI_BASTION_IP:CALI_BASTION_PORT
|
||||||
|
PersistentKeepalive = 25
|
9
wireguard-bastion/wg_configs/vanc-protected-vanc.conf
Normal file
9
wireguard-bastion/wg_configs/vanc-protected-vanc.conf
Normal file
@ -0,0 +1,9 @@
|
|||||||
|
[Interface]
|
||||||
|
Address = 10.200.20.201/24
|
||||||
|
PrivateKey = VANC_PROTECTED_PRIVATE
|
||||||
|
|
||||||
|
[Peer]
|
||||||
|
PublicKey = VANC_BASTION_PUBLIC
|
||||||
|
AllowedIPs = 10.200.20.0/24
|
||||||
|
Endpoint = VANC_BASTION_IP:VANC_BASTION_PORT
|
||||||
|
PersistentKeepalive = 25
|
Loading…
Reference in New Issue
Block a user