Add latency to calls to a specific dependency, selected at L7 by hostname (TLS SNI / HTTP Host). Works over HTTPS and for CDN/cloud endpoints with shared or rotating IPs — slows one named dependency, unlike Network Delay which slows all traffic to an IP.
Add latency to calls to a specific dependency, selected at L7 by hostname (TLS SNI / HTTP Host). Works over HTTPS and for CDN/cloud endpoints with shared or rotating IPs — slows one named dependency, unlike Network Delay which slows all traffic to an IP.
Add latency to calls to a specific dependency, selected at L7 by hostname (TLS SNI / HTTP Host). Works over HTTPS and for CDN/cloud endpoints with shared or rotating IPs — slows one named dependency, unlike Network Delay which slows all traffic to an IP.
Add latency to calls to a specific dependency, selected at L7 by hostname (TLS SNI / HTTP Host). Works over HTTPS and for CDN/cloud endpoints with shared or rotating IPs — slows one named dependency, unlike Network Delay which slows all traffic to an IP.
Adds latency to calls to a specific dependency, identified by hostname at layer 7 (TLS SNI / HTTP Host). Unlike Network Delay, which slows all traffic to an IP or CIDR, this slows only the traffic to the named dependency — and it works over HTTPS and for endpoints served by shared or rotating IPs.
Prerequisites
If you are not using our container images for the extension, the attack requires iptables (from the iptables package).
Details
A transparent TCP proxy is started in the host's network namespace. An iptables rule redirects matching outgoing TCP connections to the proxy, which inspects the connection at layer 7 — reading the TLS ClientHello SNI for HTTPS or the HTTP Host header for cleartext — to decide whether it belongs to one of the targeted dependencies. Connections to other destinations are relayed through untouched, so only traffic to the named hostname(s) is affected. Because selection happens by hostname rather than by IP, the attack works for dependencies behind shared or rotating IPs (CDNs, cloud endpoints) and over HTTPS. Each execution uses its own iptables chain, so multiple attacks can run concurrently. Matched connections are held for the configured latency before their bytes are relayed to the real destination; the delay is applied per connection.
Only TCP traffic to the targeted hostname(s) is affected. Other traffic on the host is relayed untouched.
Use Cases
Simulate a slow third-party API or downstream service and verify client timeouts and retries
Validate SLOs and fallbacks when one dependency degrades while the rest of the network is healthy
Test connection-pool and circuit-breaker behavior under sustained dependency latency
Protocol compatibility
Selection happens at layer 7, so which protocols are affected depends on how the dependency is reached:
HTTP/1.0 and HTTP/1.1 (cleartext) — matched by the HTTP Host header. Fully supported.
HTTPS (TLS), including HTTP/1.1 and HTTP/2 over TLS — matched by the TLS SNI. Supported: the fault acts at the connection level and does not need to read inside TLS.
HTTP/2 cleartext (h2c) — not matched: there is no SNI and the authority is carried in an HPACK-compressed HEADERS frame rather than a plain Host header. (h2c is rare in practice.)
HTTP/3 (QUIC) — not affected: QUIC runs over UDP and this attack intercepts TCP only. Disable HTTP/3/QUIC on the client, or target the TCP fallback, to exercise the dependency.
Parameters
Parameter
Description
Default
Dependency Hostnames
The hostname(s) of the dependency to affect. Matched at layer 7 via TLS SNI or the HTTP Host header. Required.
Duration
How long should the attack last?
30s
Percentage
Percentage of matching connections the fault is applied to.
50
Dependency CIDRs
(optional) Restrict matching to these IP addresses or CIDR blocks.
Dependency Ports
(optional) Restrict matching to these ports.
80,443
Exclude CIDRs
(optional) Exclude these IP addresses or CIDR blocks from matching.
Latency
How much latency should be added to calls to the dependency?
500ms
Reset existing connections
Reset the target's already-open (keep-alive/pooled) connections to the dependency when the attack starts, so they reconnect through the proxy and immediately experience the latency. Disable to affect only new connections.
true
Statistics
While the attack runs, a Dependency Fault Statistics widget shows how many connections were matched and faulted, a breakdown of what was done (latency applied, HTTP responses injected, connections reset, forwarded untouched), and a per-hostname table. A matched count of zero means the interception installed but no traffic hit it — check the hostname, ports, and that traffic flows through this network namespace.
Attack
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